There are a few indirect methods for imaging far-infrared radiation, relying on a visible effect caused by the infrared which can then be seen or photographed. One of these is known as evaporography.
Dr Marianus Czerny from the University of Frankfurt, writing in Zeitschrift fur Physik in 1929 (this is a big file of translated papers ... go to page 1), proposed coating a celluloid membrane with a thin layer of white napthalene and putting this in an enclosure saturated with napthalene vapour. Any areas of the coating that heated up due to infrared radiation falling on it would evaporate (sublime) and it would be possible to photograph the membrane to 'fix' a record of the patterns produced. This became known as an evaporograph.
This technique was largely unknown to the public until May 1956, when a newly-declassified device called Eva was demonstrated by Baird Associates of Cambridge Mass. The images were unmistakably thermal images and, in this case, were formed on a thin sheet of plastic coated with silicon oil. This was held in a small vacuum chamber with a salt window through which the infrared passed. The thickness of the oil film varied with the amount of radiation falling on it and interference effects resulted in this being shown as different colours with a resolution of one degree (presumably Fahrenheit). Baird's evaporographs (or sometimes evapographs) appeared in several magazines, including Time, Popular Science, Popular Mechanics and Life.
Although Baird's applications, at least as promoted, were of thermal imaging, the evaporograph principle can be applied to shorter wavelengths. Pol F Swings, who wrote a paper in 1945 on astronomical applications of evaporography, compared this to near infrared photography using Agfa 1050 plates (without ammonia hypersensitisation) and concluded that at wavelengths shorter than 1200 nm the Agfa was faster where as at wavelengths longer than 1300 the evaporograph was faster.
The process is relatively easy to reproduce, probably well within the range of a school laboratory, and a recipe currently available on the internet (scan down the page), but dating from 1972, claims to be able to record the heat from a human body after dark in ten seconds.
Tuesday, 22 February 2011
Tuesday, 8 February 2011
Infrared London at the Strand Gallery
A quick mention for an exhibition of photographs by Quentin Bell, which is running at the Strand Gallery (32 John Adam Street, London WC2N 6BP) from February 15th to 26th. It's a retrospective called A Line in the Sand and includes some infrared images from a project shot around Greater London.
Bell was commissioned by the owners of the May Fair Hotel in London to produce 105 images of London for their guest floors. You can see these on his web site. It's a nice collection, including some of my old haunts out west. The infrared artefacts are subtle: the images rely more on the textures of the film than infrared effects but you do see the occasional Wood effect creeping in.
I don't know how many of the shots will be in the exhibition, but you can always go and stay at the May Fair and see them all!
Bell was commissioned by the owners of the May Fair Hotel in London to produce 105 images of London for their guest floors. You can see these on his web site. It's a nice collection, including some of my old haunts out west. The infrared artefacts are subtle: the images rely more on the textures of the film than infrared effects but you do see the occasional Wood effect creeping in.
I don't know how many of the shots will be in the exhibition, but you can always go and stay at the May Fair and see them all!
Saturday, 29 January 2011
Is DARPA the future of thermal imaging?
Last week DARPA ... you know ... the people who invented the internet ... published a 'funding opportunity' called Broad Agency Announcement: Low Cost Thermal Imager Manufacturing
It's got this snappy URL for access to the PDF:
www.fbo.gov/utils/view?id=b332544b1b6c59a8f94eed3413e842c0
Basically they want manufacturers to come up with thermal imaging devices that can be used by 'warfighters' in much the same way most of them now use image intensifiers. They want it small, such as to work in or with a smart phone or PDA, low cost, evolutionary rather than evolutionary (no chance for the micro-yagi imager idea then) and to work in the 8-12 micron band. This was described to me by a contact at NASA as the place 'where bodies glow best'.
There's a good analysis of this story in the Register but even more interesting is the idea that this kind of thermal imager could be combined in a broad-spectrum augmented reality display which, eventually, we all could wear. These could be glasses or even contact lenses and could allow us, or an intelligent system working on our behalf, to show us a range of views of the world ranging from the visible we already see, through image intensifiers and near-infrared to thermal. Great for hill-walking or even driving at night.
If DARPA achieve their goal (which isn't certain of course) then this could be coming to a headset near you within a few years ... because DARPA want this to cost less that $500, be lighter than 25 grams and say "If successful, the IR cell phone camera-like approach will lead to widespread proliferation in military and consumer products."
I can't wait.
It's got this snappy URL for access to the PDF:
www.fbo.gov/utils/view?id=b332544b1b6c59a8f94eed3413e842c0
Basically they want manufacturers to come up with thermal imaging devices that can be used by 'warfighters' in much the same way most of them now use image intensifiers. They want it small, such as to work in or with a smart phone or PDA, low cost, evolutionary rather than evolutionary (no chance for the micro-yagi imager idea then) and to work in the 8-12 micron band. This was described to me by a contact at NASA as the place 'where bodies glow best'.
There's a good analysis of this story in the Register but even more interesting is the idea that this kind of thermal imager could be combined in a broad-spectrum augmented reality display which, eventually, we all could wear. These could be glasses or even contact lenses and could allow us, or an intelligent system working on our behalf, to show us a range of views of the world ranging from the visible we already see, through image intensifiers and near-infrared to thermal. Great for hill-walking or even driving at night.
If DARPA achieve their goal (which isn't certain of course) then this could be coming to a headset near you within a few years ... because DARPA want this to cost less that $500, be lighter than 25 grams and say "If successful, the IR cell phone camera-like approach will lead to widespread proliferation in military and consumer products."
I can't wait.
Sunday, 9 January 2011
Olympus Infrared EP1 seen at PDN PhotoPlus
This is a story that needs more research. The Phoblogger saw a specially-modified version of the Olympus EP1 at PDN PhotoPlus Expo 2010 in November. It is apparently being modified by another company but would appear to have Olympus's blessing.
This is a 'Pen' camera with 12 megapixel resolution. It has live view and since the same sensor is used for imaging, focussing and exposure, it should work well for IR.
This is a 'Pen' camera with 12 megapixel resolution. It has live view and since the same sensor is used for imaging, focussing and exposure, it should work well for IR.
Thursday, 30 December 2010
Charles Edward Kenneth Mees 1882-1960
As 2010 draws to a close it is fitting I should commemorate another key player in the history of infrared photography, who died 50 years ago: CEK (Kenneth) Mees.
Mees had a doctorate in photographic theory from the University of London and was joint managing director of Wratten and Wainwright, who had produced the first commercial panchromatic photographic plates in 1906.
Mees had joined the Croydon-based firm in 1906. The father and son team of Frederick Charles Luther Wratten and Sidney Herbert Wratten brought him in as co-owner and joint managing director when they incorporated the company on the elder Wratten's retirement (before that it was a partnership with Henry Wainwright). When George Eastman set up the Kodak research laboratory in Rochester in 1912 he brought Mees over from England to run it. In order to do so he bought the Wratten and Wainwright business. RW Wood wrote to Mees on hearing the news, hoping he had "held 'em up for a king's ransom", asking whether Kodak were going to "close up every plate factory in the world" and hoping that Kodak would now turn out "uniform plates for scientific work". Mees wrote back to reassure Wood, saying that "we shall be able to make even better plates for scientific research than we can make at Croydon".
It is possible that Wood and Mees were acquainted by letter before Wood's European sabbatical in 1910-11, but they clearly became friends and corresponded until at least the early 1950s. In 1910 Mees was an ordinary member of the council of the Royal Photographic Society, and he chaired the Traill-Taylor lecture meeting where Wood presented his Invisible Rays paper. Wood's contact address was listed as c/o Wratten and Wainwright in the RPS exhibition catalogue and it would have been Mees who provided Wood with the infrared-sensitive plates he used on his Italian travels in 1911.
Mees also made use of infrared-sensitive plates himself. The Kodak Research Laboratory archive at the University of Rochester contains thirteen photographs (negatives and prints) taken in Portugal in 1910 by Mees using Wratten and Wainwright infrared sensitised plates (one of which was included in the Infrared 100 Exhibition). The images were taken through a Wratten 88 red filter with five-minute exposures and some show the characteristic dark skies and bright foliage that we now recognise in infrared photographs. However, in his 1936 book 'Photography' Mees credits Wood with taking the "earliest photographs of landscapes by infra-red rays", presumably referring to the images from Wood's 1910 publications.
I won't go into further biographical details on Mees as I can point you to two good sources. One is from the Croydon Camera Club, of which he was a member (explore the Who is Dr Mees item in the menu), and the other is the Image, the bulletin of George Eastman House.
Finally, and nothing whatsoever to do with infrared photography, George Eastman House archives hold a 1922 note from Wood to Mees, affording a written introduction to one Leopold Mannes ...
Mees had a doctorate in photographic theory from the University of London and was joint managing director of Wratten and Wainwright, who had produced the first commercial panchromatic photographic plates in 1906.
Mees had joined the Croydon-based firm in 1906. The father and son team of Frederick Charles Luther Wratten and Sidney Herbert Wratten brought him in as co-owner and joint managing director when they incorporated the company on the elder Wratten's retirement (before that it was a partnership with Henry Wainwright). When George Eastman set up the Kodak research laboratory in Rochester in 1912 he brought Mees over from England to run it. In order to do so he bought the Wratten and Wainwright business. RW Wood wrote to Mees on hearing the news, hoping he had "held 'em up for a king's ransom", asking whether Kodak were going to "close up every plate factory in the world" and hoping that Kodak would now turn out "uniform plates for scientific work". Mees wrote back to reassure Wood, saying that "we shall be able to make even better plates for scientific research than we can make at Croydon".
It is possible that Wood and Mees were acquainted by letter before Wood's European sabbatical in 1910-11, but they clearly became friends and corresponded until at least the early 1950s. In 1910 Mees was an ordinary member of the council of the Royal Photographic Society, and he chaired the Traill-Taylor lecture meeting where Wood presented his Invisible Rays paper. Wood's contact address was listed as c/o Wratten and Wainwright in the RPS exhibition catalogue and it would have been Mees who provided Wood with the infrared-sensitive plates he used on his Italian travels in 1911.
Mees also made use of infrared-sensitive plates himself. The Kodak Research Laboratory archive at the University of Rochester contains thirteen photographs (negatives and prints) taken in Portugal in 1910 by Mees using Wratten and Wainwright infrared sensitised plates (one of which was included in the Infrared 100 Exhibition). The images were taken through a Wratten 88 red filter with five-minute exposures and some show the characteristic dark skies and bright foliage that we now recognise in infrared photographs. However, in his 1936 book 'Photography' Mees credits Wood with taking the "earliest photographs of landscapes by infra-red rays", presumably referring to the images from Wood's 1910 publications.
I won't go into further biographical details on Mees as I can point you to two good sources. One is from the Croydon Camera Club, of which he was a member (explore the Who is Dr Mees item in the menu), and the other is the Image, the bulletin of George Eastman House.
Finally, and nothing whatsoever to do with infrared photography, George Eastman House archives hold a 1922 note from Wood to Mees, affording a written introduction to one Leopold Mannes ...
who has worked out a system of color-photography which appears to me to have some novel features which I think will interest you and perhaps interest your company. It occurred to me that you might offer him the facilities of your laboratory for a few days ... The process is quite simple, and the results which I have seen look promising.[Ref]Mees did indeed provide facilities to Mannes and his colleague Leopold Godowsky Jr to work on their colour process, which eventually became known as Kodachrome. This iconic slide film was discontinued last year and the last-remaining development facility closes its doors today, at the end of 2010. So it goes.
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