Brian O'Brien Biography
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The 70mm Newsletter
|Written by: Walter
P. Siegmund and Brian O'Brien, Jr. Text prepared for in70mm.com by
Anders M. Olsson, Sweden
Brian O'Brien when he was Director of
the Research and Development at American Optical. He is seen here next to
the prototype Philips DP70 7Omm projector installed at AO.
Brian O'Brien was born in Denver, Colorado, in
1898 to Michael Phillip and Lina Prime O'Brien. His education started in the
Chicago Latin School from 1909–1915, and continued at the Yale Sheffield
scientific school where he earned a Ph.B. in 1918 and a Ph.D. in 1922. He
also did additional course work at MIT and Harvard.
In 1922 he married Ethel Cornelia Dickerman and they had one son, Brian, Jr.
After Ethel Cornelia died, he was married a second time to Mary Nelson Firth
He was a research engineer with the Westinghouse Electric Co. from 1922 to
1923. During this period he developed, along with Joseph Slepian, the
auto-valve lightning arrestor, which is still in use today.
In 1923 he moved to the J. N. Adam Memorial hospital in Perrysburg, N.Y., a
tuberculosis sanitarium run by Buffalo's Public Health Dept. Prior to the
advent of antibiotics the primary treatment for tuberculosis was fresh air
and sunshine. There was some evidence that sun tanning did help in the
remission of the disease. However, Perrysburg—40 miles south of Buffalo—had
very little sunshine in the winter. Therefore O'Brien, as physicist on the
staff, developed carbon arcs with cored carbons that very closely matched
the solar spectrum. With this development the patients could have sun
therapy year-round. Due to a general interest in the biological effects of
solar radiation, he published some of the early work on the ozone layer and
erythema caused by the sun.
O'Brien moved to the University of Rochester in 1930 to hold the chair of
physiological optics. Shortly thereafter he became the director of the
Institute of Optics. His continuing interest in the biological effects of
solar radiation led to research in vitamin chemistry. The need for vitamin
D, especially in the diet of children, had been recognized for preventing
the disease rickets, resulting in the loss of bone calcium and hence
deformation of the long bones. At that time there was no synthetic vitamin
D, but the dehydrocholesterol in milk can be converted to vitamin D by
radiation with ultraviolet light. The carbon arcs developed at Perrysburg
were an ideal source of ultraviolet, but for proper irradiation, the milk
had to be in a very thin film. Flowing down a solid cylinder produced a
suitable film, but the flow volume was much too low to be practical. Free
flow from an annular slit might work, but surface tension would collapse the
film shortly after leaving the slit. However, if by suitable vanes the milk
was given an angular velocity prior to leaving the slit, centrifugal force
would counteract the surface tension and a thin free-flowing film would be
produced. Thus, a film of high enough flow volume for commercial application
was produced, and vitamin D-fortified milk became widespread.
Since photographic materials had been a major tool in much of his work, he
became interested in the properties of silver halide emulsions. In order to
study the reciprocity effect at very short exposure times, he developed a
very high-speed slit camera that later was developed into a framing camera
with frame rates up to eleven million frames per second. This was later used
to great effect in the nuclear energy program, including the Bikini bomb
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Brian O'Brien, Gordon Milne, and Brian O'Brien, Jr. pack up camera for
By observing events in Europe it became
obvious to him that the United States would sooner or later become involved
in a major war, and so he began to prepare The Institute of Optics for
contribution to the war effort. Among the preparations: Major expansion of
instrument shop facilities, stocking up on potentially scarce materials such
as high-strength aluminum, and expanding development staff.
Early on, the Office of Scientific Research and Development was formed,
headed by Vanever Bush, reporting directly to the White House. Under the
OSRD there was formed the National Defense Research Committee with various
subdivisions. Section D, handling instrumentation, was formed under George
Harrison, and Section D6 was headed by O'Brien.
Because of its very high relative aperture, the Kellner-Schmidt catadioptric
system was to be used in many applications during the war. Therefore, a
method for mass production of the aspheric corrector plates was needed. Such
a method was developed using a heat "dropping" process onto a mold. This
used the American Optical "greenblock" molding material, which was machined
by a high-precision contouring machine developed at Rochester. The contour
of the greenblock included correction for the flow characteristics of molten
glass so the top surface of a glass plate heated on the greenblock ended
with the correct aspheric shape. All that remained was grinding and
polishing the bottom surface plano, and you had a mass-produced Kellner-Schmidt
One of the early uses for a large Kellner-Schmidt system was for a slit lamp
for night aerial photography. Fairchild had developed the slit aerial
camera, where the ground was imaged onto the film through a slit and the
film was in continuous motion at a speed related to the aircraft speed,
altitude and the camera focal length, giving a continuous strip photograph
of the ground. To use this same principle at night, a line filament lamp was
imaged through a large Kellner-Schmidt system projecting a strip of light on
the ground. The camera lens imaged this strip of light on the moving film
and produced that same strip photograph of the ground.
By far the most prevalent use of the Kellner-Schmidt optics was in the
so-called "Metascopes." These were a series of infrared telescopes with
Kellner-Schmidt optics, using an infrared phosphor in the image-plane. The
term "infrared phosphor" may sound like a contradiction in terms, violating
the second law of thermodynamics. However, if electrons can be lifted into
metastable states to be triggered out later by infrared radiation, they can
then radiate at a shorter wavelength and emit visible light.
It was rumored that an Austrian named Franz Urbach had developed such a
"phosphor," but his whereabouts were unknown. Through the various
intelligence services O'Brien tried to trace him, but with little success.
Some time later, Russell Wilkins, head of the Physics Department, came into
O'Brien's office and told him that a refugee physical chemist had shown up
in his department, and he had given him some laboratory space, but he really
didn't know what to do with him. His name was Franz Urbach, and he had
escaped the Nazis!
Urbach had, indeed, developed a phosphor-like material that could convert
infrared radiation into visible light without violating the laws of physics.
By doping sulfide phosphors with rare earth elements, primarily europium,
many possible metastable states are generated. If electrons are bumped up
into these states by high-energy radiation (initially ultraviolet light, but
later alpha particles from radium), they will stay there until triggered out
by infrared, then fall back to the ground state and, in so doing, emit
Immediately laboratory space was set up for him in the basement of Dewey
Hall, and a crew of assistants was provided. With the spherical image plane
of a Kellner-Schmidt optical system coated with this material, and an
eyepiece system arranged to view it, one had an infrared viewing telescope.
The code word "Metascope" was applied to these devices. A series of these
instruments was developed, with several going into large-scale production
for use during the war.
For example, the Sampson United Co. in Rochester was contracted to produce
the Type A Metascope, but the company had trouble ramping up to the needed
production in time for the North African invasion. To solve this, classes
were cancelled at The Institute of Optics. The undergraduates were put on a
three-shift-a-day basis in the Institute optical shop grinding and polishing
the flats on Kellner-Schmidt corrector plates. The faculty went on three
shifts at the Sampson United assembly line, and the required number of units
was produced for the invasion.
Many other devices were developed for the war effort, including the "Seebackascope"
to align a dive bomber between the Sun and a target; the "Icarascope" to
reduce the brightness of the solar disc to the point where an attacker
coming out of the sunlight could be seen; anti-oscillation mounts for
binoculars to increase the range that night fighter aircraft pilots could
identify enemy aircraft, etc. All of this important optical work was
performed under O'Brien's section D6 of the NDRC.
O'Brien on a train ride. Picture from Walter Siegmund.
After World War II O'Brien could return to his
interests in basic research in physiological optics and sensors. He
undertook a major study in the behavior of lead sulfide as an infrared
detector. He also returned to the study of the distribution of the ozone
layer in the lower stratosphere, work he had begun in the 1930s in
conjunction with the National Geographic U.S. Army Air Corps high-altitude
balloon ascents. In fact the spectrographic apparatus and even the wicker
basket to carry it into the stratosphere are still preserved at the
Smithsonian Air & Space Museum. With the development of lightweight unmanned
plastic balloons by General Mills, it was now possible to reach altitudes
above 100,000 feet— 30,000 feet higher than before the war.
These tests were made in 1949, and although the spectrograph fell into a
Minnesota lake, the film was retrieved intact, analyzed and found to have
reached only the very lower reaches of the ozone layer. It was not until
rocket probes were developed that the ozone layer was fully characterized.
(On a philosophical note, who would have thought in 1949 that the esoteric
ozone layer would prove to be such a harbinger of human impact on the
O'Brien must have enjoyed solving the unexplained riddles of human vision.
One of them was the "anomalous" Sherrington effect, which related to the
in-phase vs. out-of-phase binocular flicker for the two eyes of the
observer. While black-and-white stimuli gave the expected results,
complementary colors gave the reverse (or anomalous) results. This was
cleared up when the brightness-matching of the complementary colors was more
carefully done and the "anomalous" effect dropped out
A more demanding study was required to explain the so-called Stiles and
Crawford effect. Some time ago Stiles & Crawford observed that light
entering the eye at the edges of the pupil produced a lower brightness
sensation than light entering at the center of the pupil. This went
unexplained for many years.
O'Brien postulated that because of the structure of the retina, light
entering the retinal cones at the base travels down the cone by multiple
total internal reflections since the cone is immersed in a transparent
medium of a lower refractive index than the cone itself. Because of the
shape of the cone, light entering off-axis would tend to reach critical
angle and be lost sooner than light entering on-axis. Histological
measurements on rabbit retinas confirmed this possibility, but any direct
photometric measurements would be extremely difficult.
By scaling up the system by a factor of 6x10⁴, 3 cm X-Band microwave
radiation could be used and easily measured, if only a scaled-up retinal
cone could be produced. A then-new material made of expanded polystyrene
(now called Styrofoam) had just become available. It had the right
refractive index characteristics for X-Band radiation against air. A system
was set up using a surplus X-band military radar transmitter, and the
results exactly matched the observed results of Stiles & Crawford.
From the work on the Stiles & Crawford effect it occurred to O'Brien that a
low-refractive-index cladding on a high-index core glass would provide
insulation from adjacent fibers while at the same time give extremely high
efficiency reflections by total internal reflection. Thus a glass fiber
could transmit light over long distances without large losses, and fibers
bundled together could transmit images. Preliminary experiments with glass
fibers and an ultraviolet polymerized plastic coating showed this to be the
This study was completed at just about the time when, on a visit from Delft
in Holland, Professor A. C. S. van Heel confided to O'Brien that he had been
attempting to produce light-transmitting glass fibers for a classified
government project. His results from coating glass fibers with silver to
enhance their transmission and prevent cross talk between fibers in a bundle
had failed, and the project was in jeopardy. O'Brien pointed out to van Heel
that a low-refractive-index cladding provided the right solution, which van
Heel, of course, then recognized immediately. When van Heel applied this he
got the results he needed and went on to other things, but not before
publishing the results in the Dutch journal "de Ingenieur."
When O'Brien went from the University of Rochester to the American Optical
Co. he gave the company the fiber-cladding concept and the company patent
department began preparing a patent application. In their pre-application
search they found van Heel's publication of the concept. However they
misread the publication date (in the European sequence), and their filing
date was beyond the one-year allowance under U.S. patent law—and so the most
important concept of the patent was invalidated by van Heel's prior
publication. At the time O'Brien was absorbed with a major technical
program, the development of the
Todd-AO motion picture process, which will
be the subject of another essay.
On the other hand, the fiber concept became the basis for the rapid
development of fiber optic technology, beginning about 1955. That led to the
great contribution of fiber optics to endoscopy, night vision devices,
communications, and a host of special applications, a veritable revolution
in the field of optics.
After the war O'Brien was elected to the National Academy of Science and was
active in the Physical Sciences Division of the National Research Council,
and the Undersea Warfare Committee. Shortly thereafter General Bernard
Shriever, commander of the Air Force Systems Command, asked him to set up an
academy committee to advise the Systems Command on technical problems. This
committee was later called the Air Force Studies Board, and consisted of
scientists and engineers from a wide variety of disciplines.
James Webb, then head of NASA, requested that O'Brien set up a similar
academy committee to advise NASA on future programs. This was to be called
the Space Projects Advisory Council and had a similar composition as the Air
Force Studies Board. This was early in the space program when orbiting
objects were measured in "beer can units": It cost roughly one million
dollars to put a can of beer (one pound mass) into earth orbit. One of the
council's recommendations was that NASA develop a reusable shuttle, capable
of orbiting objects at a much lower cost. The result, of course, was the
After retiring from American Optical, O'Brien continued consulting for
various branches of the military and NASA as well as commercial concerns.
When consulting for the government he always refused any compensation,
considering it a patriotic contribution. He continued this until shortly
before his death on 1 July 1992 at the age of ninety-four and a half.
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