Colour Photography
"for his method of
reproducing colours photographically based on the phenomenon
of interference"
|
Gabriel Lippmann |
France |
Sorbonne University
Paris, France |
b. 1845
(in Hollerich, Luxembourg)
d. 1921 |
Biography
Gabriel Lippmann was
born of French parents at Hollerich, Luxembourg on August 16,
1845. The family moved to Paris and he received his early
education at home. In 1858 he entered the Lyc�e Napoleon and ten
years later he was admitted to the �cole Normale. His school
career was not markedly successful, for he concentrated only on
the work which interested him and neglected that which did not
appeal to his taste, and he failed the examination which would
have qualified him as a teacher. In 1873, he was appointed to a
Government scientific mission visiting Germany to study methods
for teaching science: he worked with K�hne and Kirchhoff in
Heidelberg and with Helmholtz in Berlin.
Lippmann joined the Faculty of Science in Paris in 1878 and in
1883 he was appointed Professor of Mathematical Physics. Three
years later he became Professor of Experimental Physics,
succeeding Jamin, and he was appointed Director of the Research
Laboratory which was subsequently transferred to the Sorbonne.
He retained this position until his death.
Lippmann, of original and independent mind, made many valuable
fundamental contributions to many different branches of physics,
especially electricity, thermodynamics, optics and
photochemistry. In Heidelberg he studied the relationship
between electrical and capillary phenomena: this led to the
development, amongst other instruments, of his extraordinarily
sensitive capillary electrometer.
Professor Lippmann had evolved the general theory of his process
for the photographic reproduction of colour in 1886 but the
practical execution presented great difficulties. However, after
years of patient and skilful experiment, he was able to
communicate the process to the Academy of Sciences in 1891,
although the photographs were somewhat defective due to the
varying sensitivity of the photographic film. In 1893, he was
able to present to the Academy photographs taken by A. and L.
Lumi�re in which the colours were produced with perfect
ortho-chromatism. He published the complete theory in 1894.
In 1895, Lippmann evolved a method of eliminating the personal
equation in measurements of time, using photographic
registration, and he studied the eradication of irregularities
of pendulum clocks, devising a method of comparing the times of
oscillation of two pendulums of nearly equal period. He
contributed to astronomy with his invention of the coelostat, a
device which immobilizes the image of a star and its surrounding
stars so that a photograph may be taken. He was also responsible
for many more ingenious devices and improvements to standard
instruments to the benefit of many branches of physics.
His work is mainly recorded in communications to the Paris
Academy of Sciences where his papers are noted for their
conciseness and originality. His method of reproducing colours
in photography, based on the interference phenomenon, gained him
the Nobel Prize for Physics for 1908.
Professor Lippmann became a member of the Academy of Sciences in
1886 and served as its President in 1912. He was a member of the
Board of the Bureau des Longitudes and a Foreign Member of the
Royal Society of London.
In 1888 Lippmann married the daughter of the writer V.
Cherbuliez, member of the French Academy.
He died at sea on July 13, 1921, during his return from a
journey to North America as a member of a mission headed by
Marshal Fayolle.
From Nobel
Lectures,
Physics 1901-1921,
Elsevier Publishing Company, Amsterdam, 1967
Nobel Lecture: Colour Photography
The problem of direct colour photography has been facing us
since the turn of the last century. Edmond Becquerel, as is
known, gave a first solution though only an imperfect one.
Becquerel showed that the colours of the image of the dark room
print on a layer of violet silver chloride. Zenker explained
Becquerel's finding by a phenomenon of interference. Experiment
shows that this explanation is not true and that Zenker's theory
does not hold good for silver chloride. Becquerel's prints
remained, however, what they were: not fixed, and fading in
light. Then Otto Wiener fixed by photography a shot of
interference fringes that are found in the neighbourhood of a
silver mirror. That physicist did not, however, envisage
obtaining colours by an interference method. I will not lay any
further stress on the background of experiments and ideas which
preceded the method on which I am to have the honour of
addressing you, and which furnishes the coloured image of
objects.
The method is very simple. A plate is covered with a sensitive
transparent layer that is even and grainless. This is placed in
a holder containing mercury. During the take, the mercury
touches the sensitive layer and forms a mirror. After exposure,
the plate is developed by ordinary processes. After drying the
colours appear, visible by reflection and now fixed.
This result is due to a phenomenon of interference which occurs
within the sensitive layer. During exposure, interference takes
place between the incident rays and those reflected by the
mirror, with the formation of interference fringes half a
wavelength distant from each other. The fringes imprint
photographically through the whole thickness of the film and
form a casting for the light rays. When the shot is afterwards
subjected to white light, colour appears because of selective
reflection. The plate at each point only sends back to the eye
the simple colour imprinted. The other colours are destroyed by
interference. The eye thus perceives at each point the
constituent colour of the image. This is no more than a
phenomenon of selective reflection as in the case of the soap
bubble or mother-of-pearl. The print in itself is formed of
colourless matter like that of mother-of-pearl or soap film.
This explanation can be checked by an experiment we are going to
carry out in front of you. Here first is a print of the spectrum
projected on to the screen. As you see, the colours are bright.
We wet the plate and project it on to the screen again. There is
no colour there. The gelatine has swollen and the intervals
between the images of the interference fringes (Zenker's laminae)
have become two or three times too large. Wait one minute while
the water dries off. We see the colours re-appear in accordance
with and at the speed of the drying process. They re-appear
according to an order which can be predicted. Red, which
corresponds to the greatest wavelengths, reappears first,
followed by orange, green, blue, and violet.
The reproduction of the simple colours of the spectrum was the
easiest to carry out. The photography of composite colours that
exterior objects present posed a harder problem. At first sight
it might have been held impossible. In effect, in the case of
simple light, the interference maxima are equidistant planes
separated by intervals equal to half a wavelength. In the case
of composite colour, an infinity of systems must be obtained for
maxima infinitely slight and with an infinity of interval values
separating them - that is to say, the whole thickness of the
sensitive layer is occupied in continuous manner by these
maxima. The spaces that exist in the instance of simple light
and which allow to assimilate the photographic plate with a
series of fine laminae have disappeared. It was thus necessary
to reshape the theory of the phenomenon in wider terms. First it
must be noted that the amplitude resulting from the interference
varies according to a function that is continuous even in the
case of simple light. The general case is derived by an analysis
based on one of Fourier's chapters. It can thus be demonstrated
that photography of composite colours is possible.
Once all theoretic reserve was gone, the technical difficulties
appertaining to the isochromatism of the films remained to be
overcome. I got quite good results from protein plates. Later,
Valenta in Vienna and the Lumi�res at Lyons found means of
coating the plates in grainless gelatine, sufficiently
isochromatic and very much better than the protein plate. Dr.
Neuhauss in Berlin carried isochromatism to perfection. Thanks
to the work of Messrs. Miethe, Krone, H. Lehmann, and others
whom I will not detain you by mentioning, the technique of
colour photography has been perfected. Allow me to show you
projections of results obtained.
(Series of slides - still-life paintings, vases with flowers,
views of Fontainebleau, Lake Annecy, Biarritz, Zermatt, Venice,
and child portrait from life.)
The photographs that you are seeing needed approximately one
minute of exposure to sunlight. The series of photographic
operations, developing, washing, final drying, takes about
quarter of an hour. Most of these pictures, taken while
travelling, were developed on the mantelpiece of a hotel room,
which proves that the method is easy enough to carry out.
It nevertheless still remains to be perfected in some points.
The length of exposure (one minute in sunlight) is still too
long for the portrait. It was fifteen minutes when I first began
my work. Progress may continue. Life is short and progress is
slow.
Source: http://nobelprize.org/nobel_prizes/physics/laureates/1908/index.html
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