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代写英国硕士论文-HAROLD EDGERTON IN WORLD WAR II( The Structure of E(8)

时间:2012-05-23 14:02来源:未知 编辑:留学生作业 点击:
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 b

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


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