The history of infrared photography

; Date: September 28, 2019

Tags: Photography »»»» Infrared Photography

How do we discover the existence of invisible things? Some claim ghosts exist, but none of us can see them. Similarly infrared light cannot be seen by our eyes, but it is now known by scientists that visible light and infrared light are only a small part of a broad spectrum of "light" phenomena.

The discovery of infrared light

William Herschel, By Lemuel Francis Abbott on Wikipedia

The existence of the infrared was discovered by the famous astronomer William Herschel. In 1800 he was measuring the temperature of light at different visible frequency bands. He did this by directing sunlight through a prism to separate the colors. Using a normal handheld thermometer he measured the heat at each color.

In an attempt to get a baseline measure of the ambient, he took a heat measurement just beyond where the red light shone. The "detector" consisted of liquid in a glass thermometer with a blackened bulb. With this he was able to measure the distribution of energy in sunlight. To his surprise the temperature there was even hotter than where the visible light shined.

This way Herschel verified there was a kind of light invisible to the naked eye.

It has since been discovered that over half of the total energy arriving from the Sun is in the infrared spectrum.

The first photographer to record infrared pictures

Source: Wikipedia

The first photographer credited with taking infrared photographs is Robert W. Wood. He was a physicist fascinated with the idea of invisible rays. As a result he became a pioneer of both infrared and ultraviolet photography.

This achievement required creation of film that is sensitive to infrared light. The earliest photographic film used a silver-halide emulsion that could not see the infrared. In 1910 Dr. Wood demonstrated infrared photography to the Royal Photographic Society. These pictures showed that chlorophyll reflected infrared strongly, while the blue of the sky appeared almost black, both of which are hallmarks of black and white infrared photographs.

One of Dr. Wood's early infrared photographs

Because of the long exposure required for his initial experimental films, over 10 minutes just for the exposure, Dr. Wood's photographs were of landscapes.

The technique also required a special barium-sodium-silicate glass incorporating about 9% oxidized nickel to eliminate all but infrared light. Today this is known as the "Woods Filter".

According to a (web.archive.org) publication by MIT the technology had been used during World War 1 for secret communications. Other sources describe infrared photography from the air as useful to see through fog and smoke on the battlefield, and to see through attempts to camouflage military equipment.

Infrared films

By the 1930's infrared photography became popular thanks to infrared-sensitive films from many manufacturers.

False color infrared photography was made possible with Kodak Ektachrome Infrared Aero Film and Ektachrome Infrared EIR. One early use of this was to detect camouflage during the 1940's.

Artistic use of infrared photography

One area that helped popularize infrared photography were artists like Jimmi Hendrix and Frank Zappa who wanted the odd-ball colors to match their odd-ball music.

Milestones in the history of infrared detectors

This table comes from (www.antonirogalski.com) History of infrared detectors by A. ROGALSKI, Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00–908 Warsaw, Poland

Year Discovery
1800 Discovery of the existence of thermal radiation in the invisible beyond the red by W. HERSCHEL
1821 Discovery of the thermoelectric effects using an antimony−copper pair by T.J. SEEBECK
1830 Thermal element for thermal radiation measurement by L. NOBILI
1833 Thermopile consisting of 10 in−line Sb−Bi thermal pairs by L. NOBILI and M. MELLONI
1834 Discovery of the PELTIER effect on a current−fed pair of two different conductors by J.C. PELTIER
1835 Formulation of the hypothesis that light and electromagnetic radiation are of the same nature by A.M. AMPERE
1839 Solar absorption spectrum of the atmosphere and the role of water vapour by M. MELLONI
1840 Discovery of the three atmospheric windows by J. HERSCHEL (son of W. HERSCHEL)
1857 Harmonization of the three thermoelectric effects (SEEBECK, PELTIER, THOMSON) by W. THOMSON (Lord KELVIN)
1859 Relationship between absorption and emission by G. KIRCHHOFF
1864 Theory of electromagnetic radiation by J.C. MAXWELL
1873 Discovery of photoconductive effect in selenium by W. SMITH
1876 Discovery of photovoltaic effect in selenium (photopiles) by W.G. ADAMS and A.E. DAY
1879 Empirical relationship between radiation intensity and temperature of a blackbody by J. STEFAN
1880 Study of absorption characteristics of the atmosphere through a Pt bolometer resistance by S.P. LANGLEY
1883 Study of transmission characteristics of IR−transparent materials by M. MELLONI
1884 Thermodynamic derivation of the STEFAN law by L. BOLTZMANN
1887 Observation of photoelectric effect in the ultraviolet by H. HERTZ
1890 J. ELSTER and H. GEITEL constructed a photoemissive detector consisted of an alkali−metal cathode
1894, 1900 Derivation of the wavelength relation of blackbody radiation by J.W. RAYEIGH and W. WIEN
1900 Discovery of quantum properties of light by M. PLANCK
1903 Temperature measurements of stars and planets using IR radiometry and spectrometry by W.W. COBLENTZ
1905 A. EINSTEIN established the theory of photoelectricity
1911 R. ROSLING made the first television image tube on the principle of cathode ray tubes constructed by F. Braun in 1897
1914 Application of bolometers for the remote exploration of people and aircrafts ( a man at 200 m and a plane at 1000 m)
1917 T.W. CASE developed the first infrared photoconductor from substance composed of thallium and sulphur
1923 W. SCHOTTKY established the theory of dry rectifiers
1925 V.K. ZWORYKIN made a television image tube (kinescope) then between 1925 and 1933
1928 Proposal of the idea of the electro−optical converter (including the multistage one) by G. HOLST, J.H. DE BOER, M.C. TEVES, and C.F. VEENEMANS
1929 L.R. KOHLER made a converter tube with a photocathode (Ag/O/Cs) sensitive in the near infrared
1930 IR direction finders based on PbS quantum detectors in the wavelength range 1.5–3.0 μm for military applications (GUDDEN, GÖRLICH and KUTSCHER), increased range in World War II to 30 km for ships and 7 km for tanks (3–5 μm)
1934 First IR image converter
1939 Development of the first IR display unit in the United States (Sniperscope, Snooperscope)
1941 R.S. OHL observed the photovoltaic effect shown by a p−n junction in a silicon
1942 G. EASTMAN (Kodak) offered the first film sensitive to the infrared
1947 Pneumatically acting, high−detectivity radiation detector by M.J.E. GOLAY
1954 First imaging cameras based on thermopiles (exposure time of 20 min per image) and on bolometers (4 min)
1955 Mass production start of IR seeker heads for IR guided rockets in the US (PbS and PbTe detectors, later InSb detectors for Sidewinder rockets)
1957 Discovery of HgCdTe ternary alloy as infrared detector material by W.D. LAWSON, S. NELSON, and A.S. YOUNG
1961 Discovery of extrinsic Ge:Hg and its application (linear array) in the first LWIR FLIR systems
1965 Mass production start of IR cameras for civil applications in Sweden (single−element sensors with optomechanical scanner: AGA Thermografiesystem 660)
1970 Discovery of charge−couple device (CCD) by W.S. BOYLE and G.E. SMITH
1970 Production start of IR sensor arrays (monolithic Si−arrays: R.A. SOREF 1968; IR−CCD: 1970; SCHOTTKY diode arrays: F.D. SHEPHERD and A.C. YANG 1973; IR−CMOS: 1980; SPRITE: T. ELIOTT 1981)
1975 Lunch of national programmes for making spatially high resolution observation systems in the infrared from multielement detectors integrated in a mini cooler (so−called first generation systems): common module (CM) in the United States, thermal imaging common module (TICM) in Great Britain, syteme modulaire termique (SMT) in France
1975 First In bump hybrid infrared focal plane array
1977 Discovery of the broken−gap type−II InAs/GaSb superlattices by G.A. SAI−HALASZ, R. TSU, and L. ESAKI
1980 Development and production of second generation systems [cameras fitted with hybrid HgCdTe(InSb)/Si(readout) FPAs].
1980 First demonstration of two−colour back−to−back SWIR GaInAsP detector by J.C. CAMPBELL, A.G. DENTAI, T.P. LEE, and C.A. BURRUS
1985 Development and mass production of cameras fitted with Schottky diode FPAs (platinum silicide)
1990 Development and production of quantum well infrared photoconductor (QWIP) hybrid second generation systems
1995 Production start of IR cameras with uncooled FPAs (focal plane arrays; microbolometer−based and pyroelectric)
2000 Development and production of third generation infrared systems

About the Author(s)

David Herron : David Herron is a writer and software engineer focusing on the wise use of technology. He is especially interested in clean energy technologies like solar power, wind power, and electric cars. David worked for nearly 30 years in Silicon Valley on software ranging from electronic mail systems, to video streaming, to the Java programming language, and has published several books on Node.js programming and electric vehicles.