指导英国硕士论文-HAROLD EDGERTON IN WORLD WAR II（ The Structure of E

HAROLD EDGERTON IN WORLD WAR II（ The Structure of Engineering Revolutions）由英国硕士论文润色专家提供资源，讲述了二战的一个著名人物。

Roozbeh Ghaffari
Ozge Nadia Gozum
Katherine Koch
Amy W. Ng
Hua Fung Teh
Peter Yang
December 15, 2000
6.933 The Structure of Engineering Revolutions
Prof. Mindell, Prof. Pratt, E. Miller
Harold E. Edgerton
2
指导assignment HAROLD EDGERTON IN WORLD WAR II
INTRODUCTION________________________________________________________________ 4
PRE-WORLD WAR II ___________________________________________________________ 6
THE BASIC STROBE CIRCUIT _____________________________________________________ 6
PRE-WAR APPLICATIONS OF THE STROBOSCOPE AND EDGERTON WORK AT MIT________________ 8
EDGERTON扴 COGNITIVE STYLE __________________________________________________ 10
WORLD WAR II ______________________________________________________________ 13
WORLD WAR II CHANGES RESEARCH AT MIT_________________________________________ 14
AERIAL RECONNAISSANCE PHOTOGRAPHY___________________________________________ 14
WORLD WAR I AERIAL PHOTOGRAPHY ____________________________________________________ 14
FLASH BOMB________________________________________________________________________ 15
EDGERTON JOINS THE WAR EFFORT _______________________________________________________ 16
DEVELOPMENT OF ELECTRONIC FLASH FOR NIGHT AERIAL RECONNAISSANCE _________________ 16
SYSTEM DESIGN _____________________________________________________________________ 17
THEORY FOR FLASH LIGHT SOURCES______________________________________________________ 19
TECHNICAL ISSUES ___________________________________________________________________ 20
THE SIX ELECTRONIC FLASH MODELS _____________________________________________ 22
BROADENING OF APPLICATIONS OF STROBE TECHNOLOGY_______________________________ 26
BALLISTIC TESTING___________________________________________________________________ 27
AIRCRAFT BEACONS __________________________________________________________________ 28
EDGERTON扴 WORKING STYLE DURING THE WAR______________________________________ 30
CONDUCTING RESEARCH_______________________________________________________________ 30
PRESENTING HIS WORK________________________________________________________________ 32
INTERACTION WITH PEOPLE_____________________________________________________________ 35
POST-WAR__________________________________________________________________ 36
EDGERTON, GERMESHAUSEN, & GRIER, INC. ________________________________________ 37
EG&G BEGINNINGS __________________________________________________________________ 37
EG&G AND WORLD WAR II ____________________________________________________________ 38
THE RAYTHEON CONNECTION ___________________________________________________________ 38
FORMATION OF EG&G, INC. ____________________________________________________________ 38
EG&G TODAY ______________________________________________________________________ 40
INFLUENCE ON EDGERTON扴 WORK_______________________________________________________ 40
CONCLUSION ________________________________________________________________ 40
WAR扴 INFLUENCE IS COMPLEX __________________________________________________ 40
CHANGE OF WORK ENVIRONMENT ________________________________________________ 40
INCREASE IN SCALE AND MAGNITUDE ______________________________________________ 41
BROADENING OF APPLICATIONS__________________________________________________ 41
NEW AREAS OF RESEARCH ______________________________________________________ 41
A KEY FORCE IN EDGERTON扴 LIFE _______________________________________________ 41
HOW WE CONDUCTED THE RESEARCH ____________________________________________ 42
ACKNOWLEDGEMENTS_________________________________________________________ 42
APPENDIX A: TIMELINE________________________________________________________ 43
3
LIST OF FIGURES
Figure 1: Shooting the Apple.........................................................................................................................................................4
Figure 2: A Milk Drop....................................................................................................................................................................4
Figure 3: Edgerton Observing a Motor with a Strobe..............................................................................................................5
Figure 4: Doc in the MIT Strobe Lab...........................................................................................................................................5
Figure 5: Basic Electronic Strobe Circuit...................................................................................................................................7
Figure 6: Karl Compton.................................................................................................................................................................8
Figure 7: The Thread Machine......................................................................................................................................................9
Figure 8: The Strobotac..................................................................................................................................................................9
Figure 9: Smoke through a Fan................................................................................................................................................... 10
Figure 10: Edgerton's Date Book .............................................................................................................................................. 11
Figure 11: A Page from One of Edgerton's Notebooks.......................................................................................................... 12
Figure 12: Boston Garden Track Meet ...................................................................................................................................... 12
Figure 13: Joe Louis Vs. Arturo Godoy..................................................................................................................................... 13
Figure 14: MIT Exhibit at New York World's Fair.................................................................................................................. 13
Figure 15: First Aerial Night Photo, Taken over Rochester, NY........................................................................................... 15
Figure 16: Flash Bombs Being Loaded..................................................................................................................................... 15
Figure 17: Major Goddard.......................................................................................................................................................... 16
Figure 18: A Pre-War Kodatron Flash Unit............................................................................................................................. 17
Figure 19: A D-3 Flash Unit........................................................................................................................................................ 17
Figure 20: High-Level Circuit Design for D-2 Flash.............................................................................................................. 18
Figure 21: Placement of a Flash Unit in a Plane.................................................................................................................... 19
Figure 22: The Inverse Square Brightness Law....................................................................................................................... 19
Figure 23: Condenser Banks........................................................................................................................................................ 20
Figure 24: Photos Taken with Flash Bomb (left) and Electronic Flash (right).................................................................. 21
Figure 25: Timeline for Electronic Flash Development......................................................................................................... 22
Figure 26: The Milk Drop (left) and Stonehenge (right)........................................................................................................ 23
Figure 27: Energy per Flash for Strobe Systems up to 1943................................................................................................. 23
Figure 28: A D-3 Flash Unit in A-26......................................................................................................................................... 24
Figure 29: Flash Units Before Installation............................................................................................................................... 24
Figure 30: Destroyed Bridge in Burma..................................................................................................................................... 26
Figure 31: Aerial Night Photograph of Normandy, June 6, 1944......................................................................................... 26
Figure 32: Photo from Ballistics Test Using Sound Trigger -- Aberdeen, VA November 10, 1943............................... 27
Figure 33: High-Speed Photographs of Explosion of 500 lb. Bomb..................................................................................... 28
Figure 34: Edgerton抯 Innovative Design for Aircraft Landing Beacons............................................................................ 29
Figure 35: Letter to Herb Grier .................................................................................................................................................. 30#p#分页标题#e#
Figure 36: Lab Set up for Gun Shots .......................................................................................................................................... 31
Figure 37: MIT from above......................................................................................................................................................... 32
Figure 38: Stonehenge Night Photographs. From the Ground, Illuminated from Above (left) and an Aerial View
(right)............................................................................................................................................................................................... 33
Figure 39: Flash Type D-2........................................................................................................................................................... 33
Figure 40: Aerial Electronic Flash Control Unit..................................................................................................................... 34
Figure 41: D2 Flash Unit in an A-20 Plane Described.......................................................................................................... 35
Figure 42: Edgerton on the field - Britain................................................................................................................................. 35
Figure 43: An Edgerton Lecture................................................................................................................................................. 36
Figure 44: An Atomic Bomb Explosion...................................................................................................................................... 37
Figure 45: Edgerton, Grier, and Germeshausen...................................................................................................................... 37
Figure 46: Wartime Network: Los Alamos, Raytheon, and Edgerton .................................................................................. 38
Figure 47: Grier, Edgerton, and Germeshausen...................................................................................................................... 39
LIST OF TABLES
Table 1: Comparison of Flash Bomb and Electronic Flash................................................................................................... 21
Table 2: Specifications of Three Major Edgerton Flash Units .............................................................................................. 24
Table 3: Specifications of Edgerton Flash Units Modified from D-2................................................................................... 25
Table 4: Types of Planes and Flash Units They Could Carry................................................................................................ 25
4
HAROLD EDGERTON IN WORLD WAR II
INTRODUCTION
Approximately twelve years before Hitler invaded Poland and World War II erupted, Harold
揇oc?Edgerton, an avid young engineer who grew up in a small town in Nebraska, headed to
the East Coast in 1926 to begin his graduate studies in electrical engineering at the
Massachusetts Institute of Technology. He later became a professor at MIT, co-founder of
EG&G, and owner of over 40 patents. In addition, he worked with
Jacques Cousteau, searched for the Loch Ness monster, won an
Academy Award, and was awarded the Medal of Freedom. He
photographed everything from milk drops to circus performers to
atomic explosions. Many MIT students recognize Edgerton抯 work
from the photographs hanging in the corridors of the Institute, such
as hooting the Apple?in Figure 1. Although many consider his
work art, he said, onmake me out to be an artist. I am an
engineer. I am after the facts. Only the facts.?
Edgerton possessed a keen interest in science and engineering. His unparalleled passion to
master the unknown in these fields is what remained constant throughout his prolific career. In
his unpublished autobiography, he recalled that one his most memorable moments was when he
built his first radio during his early childhood. Even as a child, he had the gift for creating and
building. Whether it was building a radio or making breakthroughs in flash photography, which
is what he is most recognized for, Edgerton always put tremendous effort in his work. Today, he
is often recognized for his fascinating photographs of falling milk drops and speeding bullets.
This is just one dimension of Edgerton research and accomplishments, but it has stolen the
public spotlight. The purpose of this project history is to shed light on Edgerton and his
research beyond what is conveyed by these wonderful photographs, by
examining his work around the World War II time period. The story
begins in the late 1920 at MIT.
Harold Edgerton was first introduced to stroboscopy while doing his
doctoral thesis at the Massachusetts Institute of Technology. Through
his research in stability of synchronous motors, he discovered that he
could visually observe changes in angular motion due to disturbances
of the system by using stroboscopic light. Edgerton was able to detect
changes in the rotor抯 rotation when the transmission lines connected
to the generator were perturbed (Figure 3). This breakthrough helped
him realize the tremendous power of strobe lights in allowing the
human eye to view high-speed motion that had never before been
observed. By 1937, Edgerton had already achieved a string of new
2 Harold E. Edgerton, Stopping Time (New York, NY : H.N. Abrams, 1987), 18.
3 Harold Edgerton and James Killian, Moments of Vision: The Stroboscopic Revolution in Photography (Cambridge:
The MIT Press, 1979), 4.
Figure 1: Shooting the Apple1
Figure 2: A Milk Drop3
5
innovations using strobe photography to capture fast
motion. He utilized his resources at MIT to further
develop his strobe technology. Several other
manufacturing and scientific laboratories at MIT
turned to Edgerton to help them capture fast motion
and effectively freeze time during this time period.
During the 1930s, he was developing a range of
technologies including the strobe, the multi-flash,
and the sensitometer for light measurements. As he
shifted his focus towards more artistic applications
of his tools outside of the lab setting, he faced
obstacles in taking pictures in uncontrolled conditions where weather and light conditions
became a concern. In these initial endeavors, Edgerton could not get enough reflection intensity
because the light from his flash was absorbed by particles in the open air.6 These outdoor
conditions decreased the effectiveness of his
method, which had been very successful in taking
close up photographs like the milk drop shown in
Figure 2. Compared to the lab (Figure 4) and
industrial settings, photography in an
uncontrolled outdoor environment proved to be a
challenge.
The true test came, however, in 1939 when Major
George Goddard of the Air Force presented
Edgerton with a project to develop nighttime
aerial photography for reconnaissance endeavors.
The war mobilization effort brought tremendous
time constraints to Edgerton抯 aerial photography
research. He needed to make his aerial
photography flash units reliable, and more importantly, he had to develop them quickly during
these times of international crisis. His involvement in World War II ultimately expanded the
scope of applications for his strobe technology, caused him to take his technology out of the
laboratory setting, and introduced him to research in the area of national security after the war
ended. In addition, there was a big change in scale and magnitude of the units he built during the
war.
This project history will bring to the surface lines of influence World War II had on Harold E.
Edgerton. The influences will be traced as Edgerton抯 work progressed into the war era,
followed by his work during the war and his post-war pursuits. As shown in the timeline below,
a window of Edgerton抯 life between 1927 and 1963 is studied to understand these influences
from the beginning of his inventions. The period from 1927 to 1939 is the pre-war era, when
4 Edgerton, Moments of Vision
5 http://web.mit.edu/museum/exhibits/flashinsp.html
6 Harold Edgerton, 揅ircus,?National Geographic Magazine, 20 October 1947 : 304-308. Harold Edgerton Papers.
MC 25. Institute Archives and Special Collections, MIT Libraries, Cambridge, Massachusetts, Box 105 Folder 33.
Figure 3: Edgerton Observing a Motor with
a Strobe4
Figure 4: Doc in the MIT Strobe Lab5
6
Edgerton invented the electronic control of flash duration and electronic triggering of the flash.
He perfected his technology in this time period through many engagements in the academic and
industrial world.
The years from 1939 to 1944 were the active war years, when Edgerton served the Air Force
with the technologies and competencies he developed during pre-war years and built upon them
immensely. His experiences in these years were very influential on his research and shaped the
trajectory his work would take. Between 1944 and 1947, Edgerton remained involved with the
Army through his research at MIT. In 1947, Edgerton founded his company with two other
partners and started his intense work with nuclear efforts in the United States. In 1963, after
being involved with many military applications, Edgerton ended all association with such work#p#分页标题#e#
and focused on his interests from before the war and intensified his underwater endeavors. A
close scrutiny of these three periods gives an effective and vivid picture of changes in Edgerton抯
work in terms of his work environment, the scale and magnitude of his technology, and the
broadening of applications for his technology. Thus, an examination of Edgerton抯 pre-war,
wartime, and post-war efforts illuminates the influence that World War II had on his work.
PRE-WORLD WAR II
Between 1927 and 1939, Doc Edgerton moved from using the stroboscope purely as an
observational aid, to creating a new school of technology based on electronic control of sudden
power discharge into a flash tube. During this time, he built on his original work by improving
the accuracy and the robustness of the system and varying it in terms of speed, flashing
frequency and triggering mechanisms. In all cases and designs, the main goal was the same,
aiding the human eye in seeing something it could not otherwise. Capturing a snapshot of a
moment in time was the main goal of Edgerton's technology before World War II. During this
period all his designs contained a crucial ingredient, the basic strobe technology.
THE BASIC STROBE CIRCUIT
A great deal of Edgerton抯 work evolved from his innovation to the stroboscope. Invented in
1832, the early mechanical stroboscope was simply a disk with slits at regular intervals. As an
observer looked at a moving subject through the slits in the spinning disk, he could see
successive stages of the subject抯 motion. Edgerton抯 innovations in the stroboscope were in the
areas of electronic control and trigger mechanisms. His electronic stroboscopes could emit
flashes of extremely short duration and at a high rate under precise control. The control
mechanism defined the length of the flash. This was an important design parameter determined
by the speed of the subject such that the photograph could capture an instant of the motion
without blur. The trigger system was an accurate way of synchronizing the flashes with the
motion of the subject. The fundamental technical purpose of a high-speed flash system, whether
employed as a viewing device or a photographic tool, is to overcome the human eye抯 inherent
inability to 搒ee?and therefore study fast motions as they occur. These motions would normally
be a blur to the naked eye.
Pre-War WW II Post- World War II
1926 1939 1947 1963
7
Figure 5 shows a circuit representation of Edgerton's strobe system. This basic circuit was
adapted for all of his electronic flash applications. The charging resistor RC limits the current
flowing through the capacitors during charging. The trigger switch is initially open, and the trip
capacitor C1 is charged to a voltage Vs. Vs is determined by the voltage divider composed of R1
and R2 and E, the voltage of the power source:
1 2
2
s
R R
R
V E
+
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When the switch closes, the energy in C1 is pulsed into the spark coil, and a voltage is applied to
the trigger electrode wrapped externally around the flash lamp. This excites the noble gas in the
tube (typically xenon) and decreases the breakdown voltage of the gas. When the voltage across
capacitor C is greater than the gas' breakdown voltage, the gas in the tube will ionize and create a
brief flash of light.
Characteristics of the flash such as intensity, duration, and recharge time can be controlled by
changing the values of the components in the circuit and the resistance of the tube (by using a
different gas). The flash duration is approximately given by 椒R稢, where R is the resistance of
the tube. Flash duration for Edgerton抯 electronic flash 搑anged from 1/3,000 to 3/10,000,000 of
a second.? The extremely short flash duration made possible by the electronic strobe is ideal for
high-speed photography. The flash duration of the stroboscope allows the photographer to
achieve exposure times much shorter that those permitted by a mechanical shutter, since the film
is exposed only when the flash illuminates the scene. However, the light output of the flash has
to be high enough to provide adequate light on the subject, and the subject has to be illuminated
long and intensely enough so that the image will be well-exposed on the film. The desired flash
duration should also be as short as possible to avoid blurring. These strobe parameters can be
tailored to the applications for which the strobe is used. For example, the bullet photographs
7 Harold Edgerton, Electronic Flash, Strobe (Cambridge: The MIT Press, 1983), 7.
8 Edgerton, Stopping Time, 44.
Figure 5: Basic Electronic Strobe Circuit7
8
require flash duration of 1/1,000,000 of a second, whereas hummingbird photos can be taken at
1/100,000 of a second. As a young researcher at MIT, Edgerton invested a lot of time in refining
his electronic flash and utilizing it in a variety of applications.
PRE-WAR APPLICATIONS OF THE STROBOSCOPE AND EDGERTON扴 WORK AT MIT
Edgerton抯 research and his technological focus were influenced by
changes that were taking shape at MIT. The head of the Electrical
Engineering Department at MIT, Dugald Jackson promoted new
research areas that branched off from the department抯 main focus,
power systems.10 The stroboscope was an example of the type of
research that Jackson had in mind. Thus, Edgerton continued working
at MIT following his graduation in 1931 to further his work on
stroboscopes.
Edgerton抯 plan to stay at MIT coincided with the 1929 Great
Depression, which negatively impacted the entire nation. In the early
1920抯, Karl Compton, who later served as president of MIT from
1930-1948, began promoting his vision for the Institute to become the hotbed of scientific and
technological developments, rather than being an industry-focused technical university. The
association with industry was very strong at this time. For example, the advisory committee in
charge of the engineering department抯 curriculum was composed of leaders in the industry from
companies including GE, Edison Illuminating Co. of Boston, American Telephone and
Telegraph Co. of Boston, and Westinghouse. These corporations benefited from this relationship
since they had direct access to MIT抯 people and wealth of knowledge, which they could channel
to their projects.11 Although Compton wanted to change the Institute's relationship to industry,
the Depression halted his plans. MIT maintained its close ties with American industries to
sustain its financial situation and provide resources for growth. President Compton stressed
concern about MIT抯 dependence on corporate America:
9 Karl L. Wildes and Nilo A. Lindgren Wildes, A Century of Electrical Engineering and Computer Science at MIT,
1882-1982, (Cambridge: The MIT Press, 1985), 70.
10Ibid 70.
11Ibid, 43.
Figure 6: Karl Compton9
9
MIT抯 over-dependence on industry, and more specifically on
medium size corporations in technologically stable industries, had
led to a strong emphasis on practicality and immediate utility in
engineering education. It had transformed the Institute into a
trouble-shooting agency for industry and thwarted its autonomy.13
Despite Compton抯 concern, during the Depression years MIT had
no choice but to promote consulting for industry in order to survive.
This influence of corporate America on MIT research was reflected
in Edgerton抯 consulting work with companies that wanted to utilize
his stroboscope. Thus, his ingenuity in applying his technology to
numerous applications was fostered by MIT and its role during the
Great Depression.
In 1931, with jobs scarce due to the Depression, MIT graduate
Kenneth Germeshausen came to Edgerton seeking a research position. Edgerton convinced
department head Jackson to hire Germeshausen as an assistant without pay and assigned the
former student to projects involving use of the strobe to find problems in industrial machinery.
Herbert Grier joined Edgerton in a similar fashion in 1933.15 Together, they established an
informal partnership over the years. One of their first consulting
jobs was with a paper mill company in which the machinery
moved too fast to observe the cause of the defects. Using the
stroboscope and high-speed motion pictures, they were able to
observe the motion of the machine and see where the defects were
forming.16 The stroboscope was also useful to engineers who
sought to observe fast machinery while in operation. With
Edgerton and his colleagues?help, companies such as the Russell
Box Company and the Foster Winding Machine Company utilized
Edgerton抯 stroboscope to record high-speed motion of their
machinery in action. Figure 7 shows a thread machine captured in
action by the stroboscope. For this type of work Edgerton
licensed his patent to General Radio Company in 1935 to build the
hand-held Strobotac (Figure 8). This 12-pound strobe unit could
flash up to 14,400 times a minute.
In addition to industrial clients, Edgerton also cooperated with other departments within MIT.
Figure 9 shows his work for the Mechanical Engineering department in which he examined the
movement of air through the blades of a fan. In one of his reports to the Electrical Engineering
department, Edgerton listed the 揅lass of Customers?he had for his stroboscope units and work#p#分页标题#e#
between January 1933 and October 1935. He mentioned 26.6% of his work is for clients in
12 Harold E. Edgerton and James R. Killian Flash! Seeing the Unseen by Ultra High-Speed Photography, (Boston:
Charles T. Branford Company, 1954), 132.
13 Christophe Lecuyer, "The making of a science based technological university: Karl Compton, James Killian, and
the reform of MIT, 1930-1957", p. 157.
14 General Radio Experimenter Newsletter, Vol 10, No.3 August 1935. Harold Edgerton Papers, Box 70 Folder 3.
15 Wildes,147.
16 Wylie, Francis. Unpublished article for Smithsonian. Harold Edgerton Papers, Box 5, Folder 1, p. 3
Figure 7: The Thread
Machine12
Figure 8: The Strobotac 14
10
educational fields. The remaining clients are in industry, with 17.1%
in general machinery, 9.6% in automotive and engine, 7.4% in
textiles, and 3.2% in metallurgy and metal products.17
With numerous successes in MIT laboratories and in industry,
Edgerton established the stroboscope as a valuable scientific tool.
However, machines were not the only subjects Edgerton was
photographing during the 1930抯. At one point, MIT Professor
Charles Stark Draper confronted Edgerton and said: 揥hy don抰 you
do something useful with it besides fooling around with motors??
The whole world is moving.?9 Edgerton heeded Draper抯 advice:
I looked around and there was a faucet right next to where I
worked. So I just moved the strobe over and took a picture of this
water coming out of the faucet. That was the first picture I ever
took except for a motor.20
Edgerton began applying his stroboscope to various fast-moving phenomena in his surroundings.
His images of speeding bullets, sporting events, and milk drops revealed that Edgerton had a flair
for applying his technologies to multiple disciplines and applications. The 揳bility to construct
fruitful analogies between fields?is an important mode of creative thinking.21 Much like
Thomas Edison, who applied his expertise in telegraphy to make improvements in his electric
light model, Edgerton used analogies with familiar devices like the motor and the strobe to deal
with specific, wide-ranging problems he encountered. In a speech to a chemistry class in 1936,
Doc explained that 搕here are a great many different ways to use the method [stroboscopic light],
and I feel that we have hardly learned how to use the tool yet.?Hence, Edgerton possessed a
remarkable ability to conceive countless design variations for various disciplines based on his
expertise in strobe photography. This unparalleled talent was one of the reasons why the
members of armed forces sought Edgerton抯 expertise to improve aerial photography.
EDGERTON扴 COGNITIVE STYLE
In addition to Edgerton抯 talent in applying his technology, his cognitive style, illustrated by his
incessant work ethic and meticulous nature, also made him a prime candidate for the aerial
national security project. He was very passionate about his work. He once said, 揑f you don抰
wake up 3 o抍lock in the morning wanting to do something then you抮e wasting your time.?
During the 1930抯 Edgerton and his colleagues diligently worked on perfecting the electronic
stroboscope. They experimented with various gases for the flash tubes in order to create a
brighter and faster flash. The nature of this work was much like Edison抯 light bulb work,
involving many trials and various materials. Edgerton also worked on triggering and timing
devices in order to provide precise control of the flash. This shows not only that he was an
17 Harold Edgerton Papers, Box 70 Folder 2.
18 Edgerton, Flash!, 130.
19 Roger Bruce (ed), Seeing the Unseen: Dr. Harold E. Edgerton and the Wonders of Strobe Alley (Cambridge: The
MIT Press, 1994), 22.
20 Exploring the Art and Science of Stopping Time: The Life and Work of Harold E. Edgerton. [CD-ROM] MIT
Press: Cambridge, 1999.
21 Paul Israel, A Life of Invention (New York: John Wiley & Sons, Inc, 1998), 168.
Figure 9: Smoke through
a Fan18
11
incessant worker, but that he was also intellectually curious and creative and wanted to "get to
the bottom of things." Edgerton once said, 揑f you抮e working with anything ?anything ?you
want to understand it. You抳e got to see it and record it and learn all about it.?2
Edgerton was not a theorist, but rather worked primarily from the hands-on approach. His model
for success was trial and error. 揑f you weren't actively testing your ideas, you were wasting
time. For Doc, learning by doing was most important.?4 He was not afraid of trying things and
finding a problem, but rather embraced the findings and tried again and again until the project
was refined to his satisfaction. In a draft of his autobiography, remembering his long hours as a
technician working on power transmission poles, he writes ome of these working habits have
stood me well in my life. Whenever I have a job that must be done, I think of my linemen
friends who taught me the secret ?keep going!?He was a stickler for performance. After he
came up with the design, he had to test everything he thought up. He always wanted to get to the
very bottom of things, to understand everything about it. Edgerton was not just a genius
tinkering in his lab. At the request of others and his own intellectual curiosity, he applied his
basic idea of electronic flash to many areas.
Edgerton was also very meticulous. In the MIT Archives are around 160 boxes of his work and
personal belongings. He recorded daily his activities, ideas, and findings. For example, Figure
10 shows two pages out of his date book. Records of places he went, work he had done and even
the weather on a few days are all
written down carefully by Edgerton.
In his lab notebooks, Edgerton dated
everything he wrote down and used
the same kind of bounded and
numbered institute laboratory
notebook for his records. He wrote
everything down from names of
people he met, to the trip that he and
his graduate students took, to
circuits and ideas. Figure 11
presents a sample of the many
notebook pages found.
22 Exploring the Art and Science of Stopping Time: The Life and Work of Harold E. Edgerton
23 Harold Edgerton Papers, Box 152 Folder 13.
24 Exploring the Art and Science of Stopping Time: The Life and Work of Harold E. Edgerton
Figure 10: Edgerton's Date Book 23
12
In his notebooks, Edgerton gave detailed explanations using many diagrams and photographs.
There are signatures of his colleagues and graduate students stating that they had heard and
understood Dr. Edgerton explain the concept or circuit on the page.
Doc also pasted photographs, pamphlets, and fliers onto the pages.
He worked hard, always on several projects at the same time. There
are even napkins and hotel notepad pasted onto the notebooks with
ideas and diagrams of circuits. This shows that he worked all the
time, even while traveling or eating.
Not only was Edgerton persistent, meticulous and intellectually
creative, he also knew the importance of demonstrations to the
success of his technology. Edgerton approached Kodak about
marketing his electronic flash, but Kodak refused saying they
25 Harold Edgeton Papers, Box 51 Folder1, page 22.
26 Edgerton, Flash!, 158.
Figure 11: A Page from One of Edgerton's Notebooks25
Figure 12: Boston Garden
Track Meet26
13
wouldn抰 be able to sell more than 50 of the cameras based on his
idea. So Edgerton decided to market his technology his own way,
by taking pictures of well-known events like the track meet in
Boston Garden. The picture in Figure 12 was the first flash photo
to be sent over the AP wire. Edgerton also equipped photographers
with his camera and flash so they could take stopped-motion
pictures of stars like Joe Louis in his boxing match in Figure 13.
For industrial applications of Edgerton抯 electronic flash, General
Radio agreed to build the Strobotac. The prototype was outfitted in
a suitcase, and Edgerton brought the unit with him on a family
vacation to demonstrate at factories and companies in order to build
demand. Edgerton also gave many talks and lectures to promote his stroboscope. He created an
exhibit for MIT at the New York World抯 Fair (Figure 14) exposing even more people to his
technology.
Edgerton抯 technical expertise as well as his cognitive style brought him to the attention of the
armed forces, and as a researcher at MIT, Edgerton was prepared to provide his services during
World War II.
WORLD WAR II
During the period from 1927 to 1939, Edgerton's work at MIT and in industry resulted in a
maturation of his basic stroboscopic technology and in the development of the aspects of his
cognitive style. However, this period of unencumbered research during which Edgerton
explored and developed his interests ended in 1939, when his involvement in the war effort
began. As it did for most people of academia of that era, the Second World War had a great
impact on Edgerton and marked the start of period of a change in his career. Edgerton's direct
involvement in the war effort also had a significant influence on the direction of his technology
and research and the form, which those works took. Thus, Edgerton's work during World War II
explains the new trajectories that his research followed in the aftermath of the war.
27 Edgerton, Moments of Vision, p. 82.#p#分页标题#e#
28 Harold Edgerton Papers, Box 51 Folder 3, p.148.
Figure 13: Joe Louis Vs.
Arturo Godoy27
Figure 14: MIT Exhibit at New York World's Fair28
14
WORLD WAR II CHANGES RESEARCH AT MIT
To understand the reasons behind Edgerton抯 direct involvement in the war effort, it is important
to understand the environment and time period in which he lived and worked. In particular, it is
helpful to examine MIT抯 attitude towards the military during World War II. As soon as the
United States entered the war, MIT transformed from an industry-dependent institute, to an
entity increasingly funded by the federal government. In Compton抯 eyes, MIT needed to
mobilize all of its resources and intellectual power to help in the war effort:
We are fortunate to serve as an institution whose objective in respect to national needs is
so clear-cut and constructive?In a time of military crisis, technological efficiency in
production as well as in design of instruments of defense and offense is the basic element
of national defense?We should make [best evaluation of national importance] possible
by postponing less urgent research projects, by internal rearrangement of teaching
schedules, and by carrying out a more than normal per capita burden of work.29
Both the students and the staff redirected their research and goals to meet the needs of the war
effort. In line with what was expected of MIT, Edgerton was ready to contribute. Major
Goddard, the leader of the aerial reconnaissance team from Wright Field in Dayton, Ohio visited
Edgerton during the summer of 1939 and presented him with the project of developing an
electronic flash unit for nighttime aerial photography. For Edgerton, this opened a whole new
dimension to his research that was grander in scale than his pre-war consulting endeavors.
AERIAL RECONNAISSANCE PHOTOGRAPHY
The original impetus for soliciting Edgerton抯 involvement in World War II was the need for a
more advanced system of nighttime aerial photography. Aerial reconnaissance was a tactical
operation used by the Allied forces to track enemy movements of supplies, weapons, and their
locations. During WWII, the Germans anticipated aerial reconnaissance operations. As a result,
much of the their movements occurred at night, under the blanket of darkness. Hence, there was
a need for nighttime aerial photography.
WORLD WAR I AERIAL PHOTOGRAPHY
Aerial photographs were first being used for reconnaissance during World War I. After the war,
development of cameras for aerial photography continued as nations began to see the importance
of aerial reconnaissance. In an army wide general memo, Captain Lynfold Bright wrote,
The importance of air reconnaissance cannot be overemphasized and its effect upon the
enemy抯 morale cannot be overstressed, let alone the military importance of the
information obtained through these night photographs.30
By 1928, the Royal Air Force was using aerial cameras that could photograph regions up to 4
square miles from 30,000 feet, beyond the reach of anti-aircraft guns. These cameras were
equipped with electrical heating systems to prevent the shutters from freezing at high altitudes.31
29 Burchard, 6.
30 Harold Edgerton Papers, Box 77 Folder 2.
31 British Journal of Photography 1928, Vol. 75, No. 3553, p.334.
15
The technological advancements in the United States?aerial photography research coincided
with research in Europe.
FLASH BOMB
In the United States, Major George Goddard played a
critical role in the advancement of aerial photography.
As aerial reconnaissance photography grew more
prevalent, the military learned to move at night in
order to avoid being seen by enemy reconnaissance
operations. In order to be able to track enemy
movements at night, Goddard began to investigate
night aerial reconnaissance methods. He took the first
night aerial photograph in the U.S. (Figure 15) over
Rochester, NY in 1925, using the flash bomb
technique he invented. A bomb of magnesium powder
was dropped from an airplane and triggered the
camera shutter to coincide with the flash caused by the bomb抯 explosion. The time at which the
flash bomb detonates was regulated by a time-delay fuse. When the flash illuminated the ground
below, a photocell fixed to the plane would trigger the shutter of the camera. While flash
powder made night aerial photography a reality, it was not an ideal solution. The flash powder
was dangerous due to the risk of the bomb igniting while still on the plane. Goddard narrates
many incidences in his book Overview: A Lifelong Adventure in Aerial Photography indicating
the dangers involved with the powder of the flash bomb as well as the primitive release
mechanism. In addition, the number of photographs that could be taken was limited by the
amount of explosive powder carried on the plane. In an article published in the Journal of
Physical Society of America, Edgerton described the disadvantages:
In spite of apparent success, the flash-bomb method of
night photography had several disadvantages. The flash
bomb is dangerous because the powder is easily ignited.
The number of reconnaissance operations is restricted
since the number of bombs that can be carried is limited.
The plane can operate only at a given altitude because
the time-delay fuses are set before take-off [for the
bombs] to be dropped from a pre-determined altitude.34
Because the flash bomb fuses are set before take-off, this
system has no flexibility in the operating altitude. For this
reason, inclement weather may cause problems for night
photography using flash bombs. Encountering unexpected
clouds may prevent the operators from being able to
photograph at the pre-set altitude. However, they cannot
32 Brigadier General George W. Goddard, Overview: A Life-Long Adventure in Aerial Photography, (New York:
Doubleday & Company, Inc., 1960), 179.
33 Harold Edgerton Papers, Box 80 Folder 6.
34 Harold Edgerton, "The Past, Present, & Future of High Speed Photography" Journal of Physical Society of
America July 1947, 13. Harold Edgerton Papers, Box 105 Folder 32.
Figure 15: First Aerial Night Photo, Taken
over Rochester, NY32
Figure 16: Flash Bombs Being
Loaded33
16
simply fly below the clouds, since the flash bomb would not explode at the right time. Inclement
weather in the form of wind or rain may also be problematic, since they could blow the flash
bomb off course or prevent the flash powder from igniting.
Anticipating increased use of nighttime aerial reconnaissance in World War II, it was clear to
officials in the armed forces that a safer and more versatile aerial photography technology was
needed. Edgerton was asked by Goddard to adapt his stroboscope technology for use in
nighttime aerial photography. In theory, the electronic flash system addressed most of the
disadvantages of the flash bomb:
?The equipment was inherently non-explosive.
?The electronic nature of the flash meant that it could provide a reusable and limitless
source of light.
?The light source itself was controlled internally and was contained within the
reconnaissance aircraft, meaning that it could be operated at any altitude.
These advantages were inherent to the flash equipment itself. However, the size of the system
needed to accomplish aerial reconnaissance was much greater than the systems for close-up
photos like those used to analyze milk drops and motors.
EDGERTON JOINS THE WAR EFFORT
Because of the possible advantages of an electronic flash, Goddard
approached Edgerton in 1939 with the proposition to develop a more
advanced night aerial reconnaissance than the flash bomb:
While my photoelectric system automatically opened the camera
shutter when the bomb went off and therefore assured greater
photographic dependability, the disadvantages remained and even
though the Ordnance people worked long and hard at overcoming
them, I began looking for a better method by which to light up the
sky. I found it at MIT at the electroscopic laboratory of Dr. Harold
Edgerton. I knew that Dr. Edgerton and his assistants had come a
long way in methods of generating bright light using electricity. 36
DEVELOPMENT OF ELECTRONIC FLASH FOR NIGHT AERIAL RECONNAISSANCE
Edgerton抯 work on his flash technology during the war focused primarily on creating strobe
equipment that could generate a flash with enough power to illuminate a target more than a mile
away and withstand the amount of energy such a flash would generate. At first glance, it would
seem as if the technology used to take pictures from miles in the sky would differ greatly from
that used in Edgerton抯 pre-war work in sports photography and industrial consulting. However,
a comparison of a pre-war handheld unit (Figure 18) with a wartime aerial flash system (Figure
19) shows that the basic architectures were nearly identical. In both units, the system
architecture is comprised of a flash bulb, the camera used to take the pictures, a power source
35 Harold Edgerton, "The Past, Present, & Future of High Speed Photography."
36 Brigadier General George W. Goddard, Overview: A Life-Long Adventure in Aerial Photography, (New York:
Doubleday & Company, Inc., 1960), 244.
Figure 17: Major
Goddard35
17
and capacitors to store the energy discharged in
the flash, and a control unit to trigger the system#p#分页标题#e#
and control the delay between the camera and
flash.
Thus, the wartime innovations in electronic flash
development for reconnaissance were a mere
extension in scale of pre-war flash equipment.
However, this work was not trivial, and
Edgerton抯 wartime efforts included scaling his
electronic flash components to be able to produce
the power necessary to generate beams of high
enough intensity to illuminate the ground below
and optimization of the overall system design.
SYSTEM DESIGN
While the basic electronic flash
technology remained similar to
that of the smaller pre-war units,
the design of the aerial flash unit
and its layout within the
reconnaissance aircraft were
developed to accommodate the
specific constraints of aerial
photography.
Figure 20 shows a high-level
circuit diagram of one of the
flash systems documented by
Edgerton in November 1943.
Similar to the basic strobe circuit
in Figure 5, the main idea is
charging a large capacitor and
releasing the power suddenly
into the flashtube. As an
addition, in the large aerial flash
system, the 揙N?switch prepares
the light filaments of the bulbs,
warms them up for operation,
and starts the flash bulb cooling
system that is composed of a
37 Edgerton, Electronic Flash, Strobe, 113.
38 Harold Edgerton Papers, Box 77 Folder 5.
Figure 18: A Pre-War Kodatron Flash Unit37
Figure 19: A D-3 Flash Unit38
18
simple air blower. The cooling system is necessary since the sizes of the flash units are large and
exposed to high levels of energy. This preparation is usually done on the ground prior to take off
since it draws very little current.
Once at the desired altitude, the pilot simply
pushes the 揚HOTOGRAPH?button to charge up
the capacitors. This switch connects the battery
to the power inverters where DC current is
changed to AC current. As soon as the voltage
across the capacitor reaches 4,000 volts, a relay
triggers the camera shutter, which in turn
triggers the firing of the flash. While the
揚HOTOGRAPH?button is depressed, this series
of events continues with a delay determined by
the charging speed of the capacitors.
The placement of the flash unit was another
aspect of the system architecture design. When
Edgerton worked with stand-alone stroboscope
units in his pre-war research, this was not an
issue, but now the whole unit had to be
embedded in the plane. Bombers including the
A-20 and the B-24 were modified so that both
the flash unit and the condensers housing the
large energy-storing capacitors could be located
in the aircraft抯 bomb bays. This was the logical
location for these components since the bomb
bays afforded the most space in the airplane for
the bulky condensers and its doors provided a
way to install the flash within the plane while
giving it an opening to the outside world. Given the condensers?placement in the bomb bay, the
camera was placed at either the nose or tail of the plane to provide maximum separation from the
flash unit in order to minimize the loss of contrast caused by placing a flash and camera in close
proximity to one another.
In a letter dated September 10, 1943, Edgerton relates to Colonel Baisley his findings through his
trials with one of the pilots in an A-20, suggesting two possible installations methods:
It seems possible from the available data that the flash unit for the A-20 can be modified
to be used on the bomb shackles in the rear bay beneath the tank since the tank is in the
upper portion of the bomb bay. 40
Figure 21 shows one of Edgerton抯 sketches of the installation.
39 Harold Edgerton, Description and Operating Manual Lamp-Electric Flash Type D-2 Serial No. 106 For Use in an
A-20 Airplane. (MIT, December 1943) Harold Edgerton Papers, Box 77 Folder 4.
40 Harold Edgerton Papers, Box 78 Folder 2.
Figure 20: High-Level Circuit Design for D-2 Flash39
19
The circuit and the layout design considerations were
very technical and experimental in nature. The theory
behind the requirements of the circuit and the size of
the system was derived from basic electronic flash
theory, which determines the parameters of the system.
THEORY FOR FLASH LIGHT SOURCES
The challenge facing Edgerton was the need for
increased light energy output of the flash equipment.
The output of a flash, measured in candlepower, is
integrated over the effective flash duration to determine
the total output, or CPS, measured in candle-powerseconds.
The required total output in nighttime aerial
photography is determined by two factors:
?The altitude at which the plane is flying, measured in feet. This determines the
distance between the flash and the subject.
?The lens aperture used in the camera, which determines how much light the lens, lets
in. This value, measured in f-stops, is the focal length of the lens divided by the lensopening
diameter. The aperture value becomes larger as the diameter decreases, and
less light is allowed to reach the film. This affects the flying altitudes where larger
aperture values call for being closer to the ground in order to capture enough light to
expose the film.
The combined effect of these two elements is called the Guide Factor (Equation 1, below). The
Guide Factor is proportional to the amount of light energy needed to be output by the flash
adjusted by the effect of the reflector (Equation 2). This relationship is due to the inverse square
brightness law (Figure 22), which states that the area covered by a light source increase as the
square of distance from the light source. As a result, the intensity of light per unit area decreases
as a square of distance. The light energy output (CPS) is directly related to the electrical energy
(EElec) provided to the flash bulb and the bulb抯 efficiency in transforming the electrical energy to
light energy (Equation 3).
41 Harold Edgerton Papers, Box 78 Folder 2.
Figure 21: Placement of a Flash Unit in a
Plane41
Figure 22: The Inverse Square Brightness Law42
20
Edgerton used the above calculations to determine the circuit requirements that would provide
the electrical energy for the bulb.
Edgerton also had to consider timing of the energy build-up and discharge to ensure short flash
duration at high speeds in order to avoid blurring of images.43 These calculations are determined
by changes to the capacitors and resistors that determine the time constant of a circuit.
TECHNICAL ISSUES
Despite the advantages of flash equipment for aerial
photography, electronic-flash systems were not without
drawbacks. The weight of the system, the lack of shadows in
pictures taken with electronic flash, and possible fogging of the
film were the main disadvantages in Edgerton抯 technology.
As explained in the section Theory for Flash Light Sources, for
a plane operating at higher altitudes, the intensity of the flash
required illuminating the target increases quadratically as
altitude increases. Since the power of an electric flash is
directly proportional to the capacitance of the circuit, operation
at higher altitudes requires the number of condenser units
(Figure 23) containing the capacitors to also increase
quadratically. Because the weight of the condensers dominates
the equipment, Edgerton noted 搕he weight of the flash
equipment increases as the square of the altitude at which
photographs are made.?5 Edgerton抯 initial calculations showed that the equipment required for
the operation of the flash at altitudes suitable for reconnaissance flights would weigh several
tons. However, while he initially saw this as a limiting constraint,
Goddard was completely unimpressed by the very considerable weight of the proposed
nocturnal photoflash equipment. He knew that the new airplanes, then on the drawing
board, would have no trouble carrying such heavy equipment.46
43 Harold Edgerton, 揟heory and Application of Electronic Flash.?Harold Edgerton Papers, Box 107 Folder 10.
44 Harold Edgerton Papers, Box 136.
45 Harold Edgerton, 揘ight Aerial Photography?Technology Review March 1947: 273-278.
46 Edgerton, Electronic Flash, Strobe, 289.
Figure 23: Condenser Banks44
EElec = ?Capacitance ?Voltage2
1) Guide Factor = Distance ?Aperture
2) Distance ?Aperture ?CPS ?Reflector Factor
3) CPS ?EElec ?Bulb Efficiency
21
Another issue in the use of electronic flash units in nighttime aerial photography involved the
amount of separation in distance between the flash bulb and the camera itself. A light source
placed too closely to the camera would result in 揵ack-scattered light from the source caus[ing]
fog on the film, which reduces contrast.?7 Similarly, a light source placed in close proximity to
the camera resulted in a picture without shadows. Shadows were useful in determining the
height of objects. Flash bombs were superior to the electronic flash in this regard, as the
separation they provided after being dropped from the plane was enough to produce distinctly
shadowed objects. The inability of the electronic flash units to produce shadows in the
photographs was unavoidable due to the self-contained nature of the equipment and the limited
dimensions of the airplanes. Table 1 summarizes the advantages and disadvantages of the flash#p#分页标题#e#
bomb and electronic flash. Figure 24 shows two aerial photographs, one taken with flash bomb
technology and the other with Edgerton抯 electronic flash.
Flash Bomb Electronic Flash
Advantages ?Shadows indicate heights of
subjects
?Lighter equipment
?Easy and safe to use
?Non-explosive
?Unlimited number of photos
per flight
?Operates at a range of altitudes
Disadvantages ?Number of photos per flight
limited by flash bombs on board
?Explosive material
?Operation at fixed altitude
?Problematic in inclement weather
?Heavy equipment
?Delicate bulbs
?Lack of shadow information
?Fogging of film when camera
and flash too close
Table 1: Comparison of Flash Bomb and Electronic Flash
47 Ibid, 288.
48 Harold Edgerton Papers, Box 80 Folder 6.
49 Edgerton, Moments of Vision, 138.
Figure 24: Photos Taken with Flash Bomb48 (left) and Electronic Flash49 (right)
22
In light of the advantages and disadvantages of the flash bomb method and the electronic flash
method, these two technologies served well under different conditions. Edgerton reiterates this
point, 揅ontrary to a first impression that these two distinctly different methods are competitive,
they complement each other in tactical uses.?0 His biggest challenge was not with the flash
bomb. Rather, it was with developing a technology quick enough to meet the urgent demands of
the armed forces. This is where Edgerton抯 work ethic excelled. In a letter written to Edgerton
in 1941, Lt. F.O. Carroll explained,
The probability of widespread use of flash unit for night photography is rapidly
increasing and it is indicated that the need for it will be urgent. It is therefore
recommended that the full size unit be developed with all possible haste.51
THE SIX ELECTRONIC FLASH MODELS
By the end of 1939, Edgerton had tested a quarter-scale prototype of his aerial flash in a B-18
bomber over Boston, resulting in the first photograph using aerial electronic flash techniques.
By March of 1941, Edgerton had begun testing his full-scale system over Boston, with MIT as
the subject of some of his first aerial photographs. Edgerton used these as initial demonstrations
to Goddard, who commended Edgerton for his work in August 1941:
Your flash development for aerial photography has received excellent recognition by the War
Department. They really believe that this development has tremendous possibilities, and I feel
that you should do everything possible to expedite the completion of the second unit.52
Besides his experimental trials between 1939 and 1942, Edgerton produced six different flash
units for use in aerial night photography, numbered D-1 through D-6. See Figure 25 for the
development and operation timeline for all models as well as a representation at the altitudes
50 Harold Edgerton, "The Past, Present, & Future of High Speed Photography" Journal of Physical Society of
America July 1947, 13. Harold Edgerton Papers, Box 105 Folder 32.
51 Harold Edgerton Papers, Box 77 Folder 10.
Figure 25: Timeline for Electronic Flash Development53
23
they operated at.
Each of his first three models
surpassed the previous one in
the amount of energy released
per flash. There is significant
improvement from one model to
the next, but D-1 represents the
greatest leap in technology
when compared to his pre-war
strobes. A visual comparison of
images of the Milk Drop and
Stonehenge (Figure 26)
illustrates the change in the
magnitude of flash intensities.
Figure 27 gives a quantitative
analysis of the energy per flash of the systems developed up to 1943.
The Strobotac, which was used during his consulting practices was held in close proximity to the
subject and did not require high light
intensities. The Strobotac released 0.135
watt-sec per flash, unlike the aerial
photography units where the smallest
energy level was 342 watt-sec, which
was approximately 2,500 times as
powerful. The largest flash unit was
about 250,000 times more powerful than
the Strobotac. Goddard also recognized
the challenge this application presented:
揟hey had succeeded in producing an
electric flash system for nothing larger
than a small hand-held Graflex camera,
and what I was asking for was a jump
from candlelight to sunlight.?7
Looking at the units themselves, the
differences in magnitude can be better
visualized. Figure 8 showed the
Strobotac unit manufactured by the
52 Harold Edgerton Papers, Box 77 Folder 10.
53 Synthesized from 揘ight Aerial Photography ?A Technical Story?ORDWES Laboratory, Wesleyan University,
July 1, 1954. Harold Edgerton Papers, Box 79 Folder 8.
54 Edgerton, Moments of Vision, 1.
55 Harold Edgerton Papers, Box 79 Folder 5.
56 Synthesized from Harold Edgerton Papers, Box 62 Notebook 14, p. 39.
57 Goddard, 244
Figure 26: The Milk Drop54 (left) and Stonehenge55 (right)
Energy Released Per Flash
0.135 342
3200
32000
Strobotac D-1 Flash D-2 Flash D-3 Flash
Watt-Seconds
Figure 27: Energy per Flash for Strobe Systems up to 194356
24
General Radio Company in 1935 under Edgerton抯 patent. The Strobotac can be compared to
the aerial flash units shown below. Figure 28 shows a D-3 system installed in an A-26 bomber
and the flash is being operated on the ground. Figure 29 shows two reflectors right before
installation.
In his first three units, there is an increase in energy per flash. Edgerton had to create systems
with greater energy output to enable flights at higher altitudes. Goddard explains, 揋reat altitude
to a reconnaissance pilot in World War II was money in the bank, it meant he had a much better
chance of coming home safely.?0 Delivering for this specific goal, Edgerton bettered his system
along this dimension provided that he could ready the units in time for successful operations.
Much like Draper抯 missile guidance system with increasing accuracy, Edgerton could believe in
a trajectory for his first three units. Table 2 shows the final specifications of these systems by
the end of 1943:
D-1 Flash D-2 Flash D-3 Flash
Operation Altitude
with f/1.5 Camera 1,000 ft 5,000 ft 20,000 ft
Energy per Flash 460
Watt-sec
3,000
Watt-sec
43,200
watt-sec
Capacity 75 霧
3500 Volts
375 霧
4000 Volts
5,400 霧
4000 Volts
Weight 150 lb 500 lb 5,400+ lb
Table 2: Specifications of Three Major Edgerton Flash Units61
However, the end of 1943 marks a shift as the models that follow the D-3 no longer increase
energy released per flash but rather are specific solutions to applications required by the army.
These customized solutions led to the D-4, D-5 and the D-6, which were modified versions of the
58 Edgerton, Electronic Flash, Strobe, 290.
59 Harold Edgerton Papers, Box 79 Folder 5.
60 Goddard,307
61 Harold Edgerton Papers, Box 77 Folder 4.
Figure 28: A D-3 Flash Unit in A-2658 Figure 29: Flash Units Before
Installation59
25
D-2 flash. Table 3 shows the specifications of the new units. D-4 was designed to be a
lightweight unit for low altitude flights in the South Pacific. D-5 incorporated use of standard
power inverters, which were also used in other navigational equipment like early radar. D-6 was
an improved version of D-5 that could work at higher plane speeds with less time required
between flashes.62
D-2 Flash D-4 Flash D-5 Flash D6-Flash
Operation Altitude
with f/1.5 Camera 5,000 ft 600-1,300 ft 5,000 ft 3,000 ft
Weight 500 lb 362 lb 1,400 lb 1,500 lb
Table 3: Specifications of Edgerton Flash Units Modified from D-2
Once the D-3 allowed photography from an altitude of 20,000 feet, it was no longer necessary to
pursue improvements along this dimension. Therefore subsequent models represented
improvements of the D-2 flash along other dimensions, including power requirements and
allowable plane speed.
One of the reasons the D-2 was the model in operation the longest was because it accommodated
alterations for specific purposes. In most cases, the manufactured D-3 models were reassembled
into D-2 models. Edgerton was personally involved in the re-engineering process when he took
a D-3 from Italy to England to be made into three D-2 flash units. After D-Day, sixty D-2 units
were ordered making it the most manufactured unit produced by the General Electric
Company.63
D-2 may also have lasted so long because it a fostered a good trade-off between weight and
altitude. Table 4 shows the planes that were available for reconnaissance and the units they
could carry. The table shows that the D-3 could only be used with an A-26, a luxurious
requirement during war times when planes with high bomb capacity were always being utilized
in attack fronts. Although the D-2 could not operate at the altitudes as high as the D-3, it was
nonetheless, more manageable. D-2抯 superiority over the D-1 is the ability to operate at higher
altitudes without a big impact on the weight of the unit by making more use of the plane抯 power
supply.
Admissible Flash Units
Plane Model Bomb Capacity
D-1 D-2 D-3
B-18 2,000 lb  
B-25 4,000 lb  
A-20 4,000 lb  
A-26
(aka B-24)
6,000 lb   
Table 4: Types of Planes and Flash Units They Could Carry64#p#分页标题#e#
62 Harold Edgerton Papers, Box 79 Folder 8, 27-29.
63 揘ight Aerial Photography ?A Technical Story?
26
Edgerton抯 war research was used during the China-Burma campaign in 1943. Figure 30 reveals
a blown up bridge in Burma. A captured Japanese officer said the following about the Edgerton
light unit: 揙h! What can we do now! With his bright blinking eyes streaking across the dark
canopy of night, the devil himself has compromised our last and now unfaithful mistress of
security.?6
The technology Edgerton developed during
World War II also played an important role in
the D-Day invasion of Normandy. Edgerton
recalled, "The clouds were down about 1,000
feet and the flash bombs couldn't be used at
all because they were designed to be working
at 10,000 feet."68 However, photographs taken using his aerial electronic flash enabled the
Allied forces to discover that the Germans were completely unprepared to defend an attack at
Normandy. Figure 31 shows this historical photograph. The focus of the photograph is of a
main road artery that runs through the city. This photograph shows that the road is clear with no
German supply vehicles in the area.
BROADENING OF APPLICATIONS OF STROBE TECHNOLOGY
In addition to huge increase in the magnitude that the aerial flash project brought to Edgerton抯
original strobe technology, the war also broadened its range of applications. Edgerton抯 close
cooperation with the military and the numerous wartime needs of the U.S. military during the
war led him to apply his original stroboscopic technology to a number of other, completely new
applications. These included development of technologies for the photography of ballistics tests
and the use of strobes as aircraft beacons.
65 Edgerton, Electronic Flash, Strobe, 293.
66 Harold Edgerton Papers, Box 77 Folder 2.
67 Edgerton, Moments of Vision, 138
68 Exploring the Art and Science of Stopping Time [CD-ROM]
Figure 30: Destroyed Bridge in Burma65
Figure 31: Aerial Night Photograph of Normandy,
June 6, 194467
27
BALLISTIC TESTING
While nighttime aerial reconnaissance was Edgerton抯 main focus during World War II, he also
spent a great deal of time during the war traveling to testing centers like the one located in
Aberdeen, Virginia to photograph military ballistics tests. This work built upon Edgerton抯 prewar
efforts in developing ultra-high speed movie cameras and the high-speed multi-flash, during
which time Edgerton had also gained experience in the specific area of ballistics. Prior to the
war, Edgerton had photographed bullets as they left the barrel of a pistol. He was able to show
that, contrary to what was previously thought, the 搆ick?of a fired pistol when it was shot did
not affect the trajectory of a bullet, as the gun did not begin its jerk upwards until well after the
bullet had left the barrel.
Aware of Edgerton抯 pre-war work in this area, the Army approached him about applying it to
the war effort. Edgerton quickly signed on and, at the same time that he was doing his work with
the aerial flash, also photographed a wide variety of ballistics tests throughout the war. Much of
this work involved photographing the impact of certain types of shells against armor. However,
while Edgerton抯 work with the aerial flash focused on maximizing the power and intensity of
the flash, the ballistics had a different focus. The aim of this work was to increase the accuracy
with which the flash and camera were triggered. It was imperative in ballistics testing to capture
the moment of impact at the exact instant it occurred.
This focus is apparent in the work Edgerton did during this time with sound as the triggering
mechanism for his photographs. In early ballistics tests during the war, the impact of the shell
being photographed with the armor was used to trigger the flash. However, this method resulted
in pictures that were often of poor quality or that were obscured by the flash caused by the initial
impact of the bullet with the target. In an earlier
notebook entry from November 9, 1940,
Edgerton states that he 揳gain considered the use
of a stroboscope with a sound pick up,?0
indicating that the technique had not been used
before. However, in this entry, he discusses
using this sound-triggering mechanism in the
context of diagnosing problems with looms in
the textiles industry, not in ballistics
photography. No mention is made of its
possible use in ballistics testing, and his earlier
tests during the war all use the contact of the
bullet itself with the target as the triggering
mechanism. There is no evidence of the use of
the sound technique in his ballistics photographs
prior to the war. This application of the
technology is first seen on November 10,
1943.71 In his notebook, he draws a diagram of
69 Harold Edgerton Papers, Box 52 Notebook 14.
70 Harold Edgerton Papers, Box 52 Notebook 11.
71 Harold Edgerton Papers, Box 52 Notebook 11.
Figure 32: Photo from Ballistics Test Using Sound
Trigger -- Aberdeen, VA November 10, 194369
28
the setup he uses, in a microphone is placed in front of the target and the sound wave created by
the bullet is used to trigger the flash. Clear photographs showing the instant that the shell pierces
the armor result (Figure 32). Thus, Edgerton抯 work on increasing the accuracy of the triggering
of his flash for this wartime application resulted in the development of a technique, microphone
triggering that is still in use today.
As a result of the success of this work with shells and
armor, the Army also asked Edgerton to photograph
explosions to characterize their effects. This
application also placed a great premium on the
accuracy of the triggering, as the nature of an
explosion meant that the photographer would only
have one chance to capture the instant of explosion.
For instance, in a test he conducted at the Army
testing facility in Aberdeen, Virginia on April 18,
1943,73 Edgerton overestimated the time it took for a
bomb to actually explode after it has been triggered.
As a result, he miscalibrated his flash and was left
with pictures of the bomb before it actually exploded.
Edgerton worked throughout the war on circuits and
techniques, which allowed him to increase the
accuracy of his triggering mechanisms. This work
laid the groundwork for one of his main post-war
applications of his existing technology: photography
of atomic explosions. Thus, the example of ballistics photography is an example of a pre-war
application, high-speed photography, that found a new, unanticipated application due to the
needs of the Army during the war and that remained a continuing area of work for Edgerton after
the war.
AIRCRAFT BEACONS
Edgerton抯 close collaboration with the Army Air Corps and his creative problem-solving nature
also provided a springboard for the development of other non-photographic novel applications of
strobe technology as a result of wartime needs. The growing success of the aerial flash program
drew the attention of the army, and he was encouraged to find additional applications for his
original strobe technology. Later in the war, in 1944, Expert Consultant to the Secretary of War,
Edward Bowles wrote:
For some time you have been engaged in research on and the development of this
equipment, which has now reached a stage at which it is adapted for operational military
use?While you are engaged in this project, it is desired that you take every opportunity
to examine into other possible applications of this equipment.74
72 Harold Edgerton Papers, Box 52 Notebook 14.
73 Harold Edgerton Papers, Box 52 Notebook 14.
74 Harold Edgerton Papers, Box 80 Folder 2.
Figure 33: High-Speed Photographs of
Explosion of 500 lb. Bomb72
29
One such application that Edgerton developed during the war was the aircraft landing beacon.
During his time in England conducting tests of the aerial flash unit, Edgerton noticed that pilots
returning from nighttime test flights often had a difficult time finding their landing field, due to
both the darkness and the overcast skies common to the area. The need became apparent for a
system of high-intensity beacons to allow pilots returning from nighttime reconnaissance
missions to identify their home airfields. Edgerton described the problem in a post-war
description he wrote of his wartime work in his autobiography:
I was at?Chalgrove airfield, where a night photo squadron was based?Often there was
a problem to get them home, due to atmospheric conditions. For example, on clear
nights, a heavy ground fog often appeared which covered the airfields. On other nights,
the cloud layers were very low. A standard rotation beam airport beacon was of some
help, but inadequate for the job. 75
Edgerton felt that his aerial flash unit could be used for this purpose, as a light that could
illuminate a target from miles in the sky could also be turned around and be used to signal an
airport抯 positions from miles away. Showing his creativity and hands-on approach, Edgerton
quickly jury-rigged one of his aerial flash units for use as a landing beacon. He reasoned that a
technology that could illuminate target on the ground from miles in the sky could also be used to
indicate the position of a airport to pilots flying in from miles away. While the illumination provided#p#分页标题#e#
by this system was more than adequate for the application, Edgerton found as he did
additional work on the system that the primary concern in this application was not the
maximization of flash intensity, as it was in the aerial strobe project. Instead, he found that the
main objective was to maximize the longevity of the equipment and minimize the power
consumption of the lamp, as the beacon would need to continually flash for extended periods.
As such, use of the aerial flash was not ideal for this application, as the system discharged large
amounts of energy in each flash, which both consumed large amounts of power and caused the
equipment used to deteriorate quickly.
Edgerton next proposed a system whereby a
number of smaller strobe lamps would be
arranged in a circle, pointed outwards, and
triggered in series, one after another. Such a
system had the effect of closely approximating
the coverage of the single large, powerconsuming
aerial flash lamp while consuming
only a fraction of the power. Figure 34 shows
one of Edgerton抯 initial drawings of such a
system. As this system proved most efficient
and durable, the Army eventually commissioned
Edgerton to produce beacons in this style, using
three smaller lamps. Beacons of this type are
still in use in airports today. The aircraft beacon
is one of the first examples of the use of strobe
75 Harold Edgerton Papers, Box 1 Folder 8.
76 Harold Edgerton Papers, Box 52 Notebook 13.
Figure 34: Edgerton抯 Innovative Design for Aircraft
Landing Beacons76
30
technology in non-photographic, non-imaging applications. Thus, Edgerton抯 involvement in the
war with the aerial flash afforded him opportunities to apply his technology in ways that he did
not envision before the war.
EDGERTON扴 WORKING STYLE DURING THE WAR
At the end of the war period, the Secretary of War requested Edgerton to investigate further
applications of his technology, indicating that the armed forces were pleased with Edgerton's
work. He successfully designed and deployed six models of electronic flash units for aerial
photography however, his technical ability was not the only factor in his success in this project.
His working style which can be observed in his activities before World War II, specifically the
ways in which he conducted his research and presented his work to others, contributed to his
success.
CONDUCTING RESEARCH
Edgerton was very diligent in the way he put
his ideas on paper and into graphical
representation. Like his lab notebooks in the
pre-war era, Edgerton consistently records
information about the experiments that he
carries out for the Air Force. This is needed to
both determine his next steps and facilitate his
regular reports to the army officers. Many of
Edgerton抯 documents from the war times
found in the MIT Archives were in forms of
correspondence between Edgerton and people
in the field or people back at MIT who helped
him with his work. Figure 35 shows part of a
letter Edgerton wrote to Grier during test
flights at Wright Field in summer of 1942.
The letter relates the events that happened
during the tests as well as technical
information. Similar to his pre-war lab books
where he jotted down ideas as they came to
him, he uses these correspondences to scribble
rough circuits or system diagrams. In this
particular example, he sends Grier a piece to
work on before his arrival at MIT to speed up
the project.
One significant change in the way Edgerton carried out his research was the setting where he did
his experiments. Prior to war, he was dealing with small-scale projects where either, he would
prepare up his equipment and setting or he would be operating a mobile stroboscope unit into
another closed setting like a manufacturing plant, or a machine room. Figure 36 shows an
77 Harold Edgerton Papers, Box 78 Folder 1.
Figure 35: Letter to Herb Grier77
31
example of a lab set up where Edgerton could control all the parameters that could influence the
effectiveness of his equipment. In such a situation, the experiment can be repeated many times
until the desired results are obtained. When compared to the air force bases where he did his
work, this is a big change. He was in an environment where he did not have access to resources
of his lab. Goddard recalled when Edgerton arrived in Chalgrove, Britain with some
reconnaissance pilots:
He was a great improviser so instead of
beefing to the Commanding Officer, he
immediately went to the base dump and
scoured a number of large wooden airplane
and glider crates. In a few days, he and his
men were sitting in a comfortably equipped
office containing stoves, desks, chairs, filing
cases, and a nanny! This was typical of the
Doctor for he was a man of action and always
got the job done with distinction.
The men at Chalgrove marveled at his
unbounding energy as they saw him in
coveralls clinging in and out of airplanes and
dashing to his machine shop and about the
field on personnel training schedules.79
His resourcefulness often also allowed him to
make fast progress despite difficulties. When a
shipment of flash tubes arrived broken, he went to Siemens Company in England and asked them
to manufacture some xenon bulbs. As xenon was not readily available in the UK, Siemens
turned him down. Edgerton managed to obtain 3 liters of xenon and returned to the company
two days later, much to the surprise of Siemens?president.80 Yet, this was a different operating
mode than he had at MIT, where he could walk down the hall to the spare parts room and browse
and get whatever he needed.
Another challenge of working in the field was testing. Experimentation of his equipment
required the installation in a plane, flying the plane and testing the quality. This process took a
long time, and could only be repeated at night. Edgerton was present and onboard inmost of
these trial flights. Each flight test would require installing the equipment in the plane, take-off,
taking of the pictures and recording of the parameters, landing and deinstallation. It was a time
consuming and expensive process unlike any in lab tests. Besides, reflecting how hard it is to
conduct tests and have them run smoothly each time, Edgerton抯 letters have a tone of
accomplishment in each. Each letter shows a modification or an improvement that he designs to
better his technology. This shows how passionate and excited he was about his work and
involvement with the war effort. John Burchard in his accounts of MIT in WWII says:
78 Harold Edgerton, 揃ullet Photography,?High Speed Photography and Photonics Newsletter, Fall 1981, p.8.
Harold Edgerton Papers, Box 109 Folder 48.
79 Goddard,329-30
80 "Edgerton, Killian, Duncan 3 April 1978" [Audio tape] Harold Edgerton Papers, Box 143.
Figure 36: Lab Set up for Gun Shots78
32
The important thing to remember is that these men were ready - that they did not wave
magic wands - and that the reason that they were ready was that as free men in a free
institution they had been permitted to proceed on projects which caught their imagination
without any insistence on the part of their superiors that they be able to forecast a payoff.
81
Edgerton抯 excitement about his work is also observed through the amount of thinking he puts
into his products and their perception by others.
PRESENTING HIS WORK
Working on photography and motion pictures before the war, Edgerton had a vehicle for
demonstrating his work to others. His audience in the pre-war years included people from
academia, clients from industry and manufacturing companies who built under Edgerton抯
patents. However, none of these demonstrations were at as great a scale as those he had during
the war.
Although Edgerton had Goddard抯
support, he had to demonstrate his
technology to the decision makers and
potential users of the equipment. The
first demonstrations came as he
developed the unit and flew it over MIT
in 1941. Figure 37 shows a photograph
of the Institute.
Edgerton also arranged a dramatic public
demonstration of his technology for
British military personnel using
Stonehenge as his subject. One can also
see this type of heterogeneous
engineering demonstrated in Thomas
Edison at his Menlo Park Laboratory.
Thomas Edison used his Menlo Park
demonstration to unveil his electric
lighting system to the public and
generate enthusiasm. 83 Similarly, Edgerton picked a prominent British landmark to influence the
officers to use and support the electronic flash. Edgerton recalled in an interview:
Six more senior officers and me were the decision makers. I was the only defender of the
xenon flash?(I wanted to show them what it could do. No pilot wanted to fly for me.)
They thought they did not have a target. At conclusion, we suggested that let抯 get a
target. And they got excited. I said the Stonehenge. Worked well!84
81 Burchard, 204.
82 Harold Edgerton Papers, Box 77 Folder 2.
83 Israel, p. 187.
84 "Edgerton, Killian, Duncan 3 April 1978"
Figure 37: MIT from above 82
33
This demonstration was successful in building enthusiasm and support for his electronic flash
equipment. However, Edgerton抯 job was not done after convincing the decision makers to#p#分页标题#e#
allocate resources for nighttime flash photography. He also had to gain the favor of the pilots
and technicians who would be using the equipment.
Working with the pilots, Edgerton had to overcome some psychological obstacles, 揗y biggest
problem was the fighter pilots. They came there to fly and fight. They did not want to have
anything to do with flying a camera around.?7 Edgerton soon figured out how to motivate them.
When he discovered a nudist camp in England, he kept the coordinates secret, and only the few
pilots that flew for him
learned the location.
Edgerton also used his
documentation of the
equipment, and the actual
artifacts to gain the interest
of the men in the field.
Edgerton was allowed to
train the soldiers only once.
Therefore, at all times, his
units were accompanied by
documentation to train the
people. The first page of an
operating manual about D-2
usage in A-20抯 he sent to the
army contains a picture of an
officer holding the control
85 Roger Bruce (ed), Seeing the Unseen: Dr. Harold E. Edgerton and the Wonders of Strobe Alley (MIT Press:
Cambridge, 1994). Image from accompanying CD.
86 Description and Operating Manual Lamp-Electric Flash Type D-2 For Use in an A-20 Airplane December, 1943.
Harold Edgerton Papers, Box 77, Folder 4.
87 "Edgerton, Killian, Duncan 3 April 1978"
Figure 38: Stonehenge Night Photographs. From the Ground, Illuminated from Above (left) and
an Aerial View (right)85
Figure 39: Flash Type D-2 86
34
unit, showing that his device is manageable (see Figure 39). The flash is not installed and
depicts the device abstracted from the complications of the plane and connections.
The manual continues by introducing the objectives of the technology. Whenever the army
asked him to build a flash unit, he would be told the desired height of operation. Moreover,
when tests were conducted with these units, and recordings were made, the most consistent
information recorded by the pilots is the altitude of flight.88 Edgerton, aware of this concern
about height, mentions that exact information in the first sentence of his product manual:
搮highly effective for military purposes at altitudes up to 10,000 ft厰
He continues his introduction with a very social approach to the usability of the device.
Edgerton uses this kind of 搒oft?approach in many situations, and he is also aiming to kindle
some ease in the operator that the device is simple to use:
This device produces, at the touch of a button under the control of the pilot, lighteninglike
flashes of intense actinic value for night, dusk, or dawn aerial reconnaissance.
Next he touches on issues that the pilots are most concerned with, their security while flying and
flashing the system and questions around being an open target to the enemy:
The new technique promises greater chance of avoiding antiaircraft defenses?The flash
is virtually silent?The brevity of the flash gives the enemy little advance notice?There
is no explosive hazard.
Edgerton then adds the points around the ease of use of the system:
Once the apparatus is synchronized, it requires no further adjustment. The equipment has
been designed to be installed or removed easily.
The control unit, shown in Figure 40, is operated
with one button only and the control settings are
extremely simple and self-explanatory. This is
ideal for a pilot to use especially when the rest
of the plane equipment he needs to operate is
extremely complex. He uses the black box idea
to abstract the pilot from all the connections and
complications of the actual setup.
The rest of the operating manual is geared
towards technicians who will be maintaining
and fixing the equipment when Edgerton is not
with them. At this level, Edgerton provides a
semi-detailed blue print, shown in Figure 20.
He proceeds to present a cookbook of the
88 Harold Edgerton Papers, Box 78 Folder 8.
89 Harold Edgerton Papers, Box 78 Folder 6.
Figure 40: Aerial Electronic Flash Control Unit89
35
installation process with step-by-step instructions, 搮emergency bomb release should be
checked. Two other cables must be installed?install a No. 17 flashtube before lifting the unit
into the airplane. Hold the tube vertically厰 90
Following the instructions,
Edgerton includes detailed
descriptions of the power supply,
the flash bulb with details that are
needed to fix or disassemble the
unit. These three main sections
of the manual form a document
where the level of details are very
well balanced and organized.
This shows how much Edgerton
thought about making his unit
attractive in terms of usability
and operation friendly.
In addition to the operating
manual, Edgerton also uses
graphic aids and photographs to
ease the explanation of the
technology in his correspondences and documents. Figure 41 shows a very high-level
installation of the equipment and basic specifications. This document is geared towards the
pilots who would like to understand the modifications made to the plane or senior officers who
would like to get a general idea and associate the terminology with the actual equipment.
INTERACTION WITH PEOPLE
Even though Edgerton was very successful in educating
through his documents, his desire for hands-on teaching
lead him to arrange for a group of enlisted men to come
to MIT for training in flash technology during August
of 1943. Not only did Edgerton teach them in a betterequipped
environment but also he was also able to get
to know them better during the training. In his talk with
John Duncan, Edgerton recalls the extraordinary
experience during the war, 揑 still get letters from these
fellows. We took one guy from South Carolina skating,
he has never seen ice before.?2
In addition to the stories Edgerton narrates, excerpts and
pictures in his lab notebooks display his enthusiasm
90 Description and Operating Manual Lamp-Electric Flash Type D-2 For Use in an A-20 Airplane December, 1943.
Harold Edgerton Papers, Box 77 Folder 4.
91 Harold Edgerton Papers, Box 137.
92 "Edgerton, Killian, Duncan 3 April 1978"
Figure 41: D2 Flash Unit in an A-20 Plane Described
Figure 42: Edgerton on the field -
Britain91
36
about being a part of the Army and the war effort. In one of his lab notebooks, he describes the
prelude to a reconnaissance mission. 93 He lists all the military personnel involved and their roles
in the mission and the entry contains little technical writing. Many of the accounts in his lab
notebook during this period contain narration of the day抯 events. This highlights his interest in
people and the nature of his relationships. This interest is also evident in the numerous pictures
of co-workers, military officers, and students pasted in his notebooks (see Figure 42, HEE
standing in the middle holding a large reflector). His positive attitude and passion for his work
are main thrusts to his success during the war.
As the war ended, he resumed his role as a
professor at MIT, asking the army for aerial
units to be used for education losing no time to
get back to his passion for teaching:
I should like to recommend that a complete
D-5 unit be permanently assigned to MIT for
use in educational and experimental work in
night photography?There is one K-19
camera, two intervalometers, two spare
condenser banks for D-2, and several other
small items here at MIT?I suggest that this
material likewise be permanently assigned to
the institute for the educational and
development projects, which will
undoubtedly come up in the future.95
Harold Edgerton enjoyed his work and also the people with whom he worked. From the way he
conducted research to how he presented his work to actually working with people Edgerton
continued his style from his pre-war years. His working style during the war definitely
contributed to his overall success.
With the end of World War II in 1945, Edgerton ended his involvement with his main wartime
project, the nighttime aerial flash. However, the work he did during the war had the effect of
increasing the magnitude and scale of his technology, broadening the range of applications that
he applied it to, and further expanding and devloping the methods with which he did his work.
In addition, his wartime work in many ways shaped and defined over the trajectory of much of
his work after the war, especially by creating networks that stuck with Doc in the post-war era
and shaped a significant part of his work till 1963.
POST-WAR
Most of the influences and changes traced in Edgerton抯 work up till this point involve the same
basic technology ?the electronic flash. From the early milk drop photographs to the aircraft
beacon, all the applications involved the short and powerful (and sometimes periodic) discharge
93 Harold Edgerton Papers, Box 53 Notebook 15, p. 6.
94 Wildes, p. 150.
95 Harold Edgerton Papers, Box 78 Folder 6.
Figure 43: An Edgerton Lecture94
37
of electricity through a gas tube, causing a bright illumination. The
period of time towards the end of the war and following the war
represents a significant deviation from this model. He delved into
applications that did not necessarily involve commercial, artistic, or#p#分页标题#e#
observational photography or illumination. Some of the more notable
applications that sprung from his technology in the 10 to 15 years after
the war were:
?Firing systems for nuclear bombs,
?Methods for photographing nuclear explosions, and
?Side-scan sonar for underwater exploration.
In 1947, Edgerton, Germeshausen, and Grier formed EG&G (named
from the first letter of each man's last name). EG&G became a leading
government contractor for testing and designing nuclear weapons. The work he did at EG&G
was unlike the work he had prior to the war. It is thus a pertinent example of a new research path
of Edgerton抯.
EDGERTON, GERMESHAUSEN, & GRIER, INC.
EG&G BEGINNINGS
In the early 1930's, Edgerton, Germeshausen, and
Grier worked together to solve problems in industry
using the stroboscope. Grier recalls the division of
labor in early days of the partnership:
[The partnership] was an effort to achieve, as a
group, more than we could as individuals. Doc,
in particular, was a full time professor and
trying to promote the stroboscope essentially in
his spare time. Germeshausen was the
researcher who undertook the actual
development of tubes that could be used over
and over again, and my role I guess, was the
putting together of equipment we could use.98
Interestingly, their roles seem analogous to positions in a modern corporation. Edgerton was
effectively the Chief Technical Officer, Germeshausen was the Chief Engineer, and Grier was
the Chief Executive. Grier even mentions that Mrs. Edgerton was the 揅hief Financial Officer?
since she ran the accounts. They found agreement in division of labor and their talents were
complimentary. Bernard O扠eefe, a navy officer, who also worked with the group at EG&G,
recalls the effectiveness of their union:
96 Edgerton, Moments of Vision, p. 134.
97 Wildes, p. 152.
98 揈G&G?[Audio Tape] Harold Edgerton Papers, Box 143.
Figure 44: An Atomic
Bomb Explosion96
Figure 45: Edgerton, Grier, and
Germeshausen97
38
They simply pooled their resources and worked together on whatever consulting or
measurement problem came along. Throughout the thirties they prospered as their
abilities became more widely known. 99
EG&G AND WORLD WAR II
According to Germeshausen, the war 損ermanently changed the direction of the partnership.?
When the U.S. entered the war in December 1941, Edgerton, Germeshausen, and Grier were
assigned to different projects. Edgerton spent most of his time developing systems for nighttime
aerial reconnaissance. Germeshausen went to the MIT Radiation Laboratory, which dealt mostly
with wartime radar development. There he developed a series of gas switching tubes for radar
modulation. Grier went on to work at Draper Lab with the famous Stark Draper. However, both
Grier and Germeshausen maintained a limited involvement with the nighttime aerial
reconnaissance program. In particular, Grier was working at Raytheon on the construction of the
aerial reconnaissance units. Grier抯 work at Raytheon, ironically, set the tone for the direction of
the partnership in the post-war era.
THE RAYTHEON CONNECTION
Los Alamos Scientific Laboratory, the
U.S. headquarters for nuclear weapons
research, needed high-energy capacitor
banks, but they did not have time to
develop their own. These capacitor banks
were to be employed in the design of a
firing set to trigger the explosion of an
atomic bomb. Raytheon was building the
firing sets, and was also making capacitors
for Edgerton抯 aerial photography project.
Robert J. Oppenheimer, Los Alamos?
director, realized these capacitors would suit his project's needs. Because of Grier's connection
to Raytheon, Oppenheimer hired him as a consultant and commandeered the plant to build
capacitor banks for Los Alamos. The schedule was so tight that they did their first full-scale test
of the system at Tinian Island in the Marianas the day before it was used at Nagasaki.?00
The network between the night aerial photography project, Raytheon and Los Alamos that was
established got Edgerton and his apprentices involved in the Manhattan project (Figure 46).
They were able to carve a niche for themselves in the development of firing sets. This proved
pivotal in the eventual formation of EG&G, and subsequently, in expanding the scope of
Edgerton抯 work.
FORMATION OF EG&G, INC.
After the war, the Atomic Energy Commission decided that the country had to
maintain substantial research in nuclear technology. Los Alamos let a contract to
100 Ibid.
Aerial Strobe
Raytheon
Manu. Co.
Los
Alamos
Edgerton Oppenheimer
Grier
Figure 46: Wartime Network: Los Alamos, Raytheon,
and Edgerton
39
the three of them had been working on firing set development for a while and had become
prominent players in the nuclear world. Edgerton, Germeshausen, and Grier were therefore
consulting again, now in the nuclear test and design business.
The formation of EG&G was influenced by a shift in MIT policy and by the Atomic Energy
Commission. O'Keefe states:
James Killian, the MIT president, was not happy about the size of the project, since the
Institute was going through one of its periodic attempts to divest itself of government
contracts.101
According to John Burchard, this was because MIT was trying to re-deploy for peace after
WWII. He stressed that since MIT had taken more active a role in the war than any other
institution in the U.S., MIT staff was 搈ore completely diverted from education.?02 Therefore
the Institute took a harsh stance against military work immediately after the war. Nevertheless,
since the Atomic Energy Commission (AEC) required their services, Edgerton, Germeshausen,
and Grier had no choice but to move off campus to continue the work. EG&G incorporated in
1947:
At the end of the war MIT decided against having such highly classified work on campus.
Since the Atomic Energy Commission wanted the work continued, the three partners
formed a corporation and became a prime contractor to the AEC.103
Thus, it is evident that the impetus for the partnership's revival and subsequent officiation
primarily sprung from an interplay between MIT抯 attitude to military research and the
government's nuclear effort, both directly related to World War II.
After incorporation and free from MIT抯 pressure, the
partners were free to undertake any government work
they pleased. EG&G subsequently was asked to build a
special firing set for a series of full-scale weapons tests
that were to be undertaken at Eniwetok in the Marshall
Islands in 1951. They were also tasked to deliver a
network of timing signals for the experimenters who
would be participating. This eventually became a big
responsibility, requiring millions of dollars of
submarine cable and instrumentation. The government
then added neutron multiplication measurements and
technical photography to their agenda and the
corporation expanded rapidly.
101 Ibid.
102 Burchard, p. 313
103 Wildes, 151
104 Edgerton, Moments of Vision, p. 169.
Figure 47: Grier, Edgerton, and
Germeshausen104
40
EG&G TODAY
Today, the U.S. government is still one of EG&G's most important customers.
The company's website states that it is a 搇eading provider of management and
technical services to agencies of the U.S. government and commercial businesses.?05 It seems,
however, that the bulk of its projects remain government-related. EG&G consists of four
operational divisions:
?Defense Systems and Services
?Logistics
?Ranges & Installation
?Science & Engineering
Major customers include NASA, the Secret Service and The Departments of Defense, Energy,
Transportation and Justice. Major commercial clients include Boeing and Lockheed Martin,
which are also highly defense-related. EG&G抯 two most recent contracts were for the US Air
Force (estimated at $72 million) and the Naval Systems Air command, signifying their strong
links to the military. What was once a small company solely in charge of nuclear triggering
matured into a multi-million dollar corporation that specializes in a multitude of disciplines.
INFLUENCE ON EDGERTON扴 WORK
The war brought a new dimension to Edgerton's research. Before the war he used his technology
for high-speed photography and industrial consulting. These consulting projects were funded by
private firms whose interest was in improving processes in order to increase profits. During and
immediately after the war, however, the government became a major client of Edgerton, and
their interest was primarily National Security. This resulted in his work taking on two separate
trajectories. He continued his work in the electronic flash after the war, but EG&G also became
a significant part of his research life.
CONCLUSION
WAR扴 INFLUENCE IS COMPLEX
As Carl Von Clausewitz aptly put it, 揥ar is a continuation of politics by other means.?This
definition sounds simple and straightforward enough. However, huge socio-political
implications accompany a state of war. The multi-faceted nature of war influences every
individual in a myriad of fashions. Edgerton has been shown to be no exception.
CHANGE OF WORK ENVIRONMENT#p#分页标题#e#
The war made aerial reconnaissance a strategic requirement for the Allies. Edgerton抯 nighttime
aerial flash technology was an effective tactical means of meeting this requirement. This is
precisely why Major Goddard first approached him, and how Edgerton eventually got involved
in the war. He was 揺xtracted?from his familiar, calm laboratory setting and taken into the
battlefields in England and Italy, where conditions were uncontrolled and tumultuous. This
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INCREASE IN SCALE AND MAGNITUDE
Having become involved in the war, the most immediate effect Edgerton抯 work experienced
from the war was new technical requirements. Power was now the name of the game. Prior to
the war, the aim of Edgerton抯 strobe photography was to capture motions which occurred too
fast to be observable to the naked eye. His chief concerns were accuracy of triggering and flash
duration. Aerial reconnaissance, however, called for flashes 100 times more powerful than those
before the war. The flashes had to sufficiently illuminate terrain thousands of feet away from the
plane as opposed to a milk drop inches away from the camera. Thus, power, and consequently
weight, of his flash units increased tremendously as a direct result of the war.
BROADENING OF APPLICATIONS
Edgerton抯 newly formed link with the military also gave rise to new applications for his
electronic strobe. The nighttime aerial strobe was the first in a number of wartime applications.
Other examples included ballistics photography and aircraft beacons. The aerial selectronic flash
may also have led to his development of the side-scan sonar. Hence, an obvious effect of the war
was the ensuing broadening of applications.
NEW AREAS OF RESEARCH
The war also had an indirect, but not insignificant, influence on Edgerton抯 work in the form of
the relationships it engendered. The war formed a network between parties and organizations
that began working together for the same cause. The aerial strobe project and Los Alamos were
two separate entities that linked up because of their respective relationships with Raytheon. It
was because of this connection that Los Alamos was able to tap the expertise of Edgerton and his
associates. These relationships represented the beginning of a new research realm for Edgerton.
A combination of MIT抯 anti-military attitude and National Security Policy immediately after the
war also facilitated the founding of EG&G, which was to undertake this new dimension of
research and eventually become a major part of Edgerton抯 legacy.
A KEY FORCE IN EDGERTON扴 LIFE
In conclusion, war is a unique state of affairs that impacts all aspects of society. World War II抯
influence on Edgerton抯 work cannot be traced to one particular line or trajectory. The war
changed everything from his work environment to the actual technology he researched. There is
no doubt however, that it was a pivotal force in the life of the Harold E. Edgerton.
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HOW WE CONDUCTED THE RESEARCH
A significant portion of our research was conducted at the MIT archives, where we examined all
of Edgerton抯 notebooks and materials that he had compiled and donated to MIT. The most
challenging aspect of a project history on Edgerton is being able to focus on a single specific
topic. Edgerton had such a prolific career that it is hard to choose a single path to study. By
searching through these primary sources we were able to narrow our topic to events surrounding
World War II, which the MIT Archives had well documented. We also interviewed Edgerton抯
student, Professor Kim Vandiver, and Dr. James Bales of the Strobe Lab. They gave us insight
on who Edgerton was on a personal level and also shed light on the technical side of Edgerton抯
tools. All of the equipment demonstrated during the presentation were borrowed from the Strobe
Alley.
指导essay ACKNOWLEDGEMENTS
We would like to thank Professor David Mindell, Professor George Pratt, and Eden Miller for
their guidance and input this term, Professor and Dean Kim Vandiver for talking with us about
Doc Edgerton, Dr. James Bales for providing us with information and the use of equipment, and
the staff at the MIT Archives for all their help with our research.
Please visit "Edgerton in World War II" online at: