Artem vs. Predator

Infrared film used to be available commercially with sensitivity up to 900nm. It was quite useful for aerial photography work – forestry, surveying, spying. Very little of it is still around. Kodak Ektachrome was what one could get for your high school dark room. Aerochrome for surveying work. It was discontinued in 2009. Ilford however still makes some. Be forwarned, finding someone to develop the stuff is a nightmare, the chemicals are toxic, and the shelf-life brief.

Scientific infrared films, such as special formulations of AeroChrome I, II, II, approached sensitivity up to 1200nm.

In surveillance work, objects which were painted to look like their natural environment using various organic or inorganic paints may show up quite differently in the infrared spectrum.

In forestry work, old growth tree populations could easily be distinguished from new growth tree populations and were one of the primary uses for Nasa's version of the U2 (ER-2) for identifying old-growth redwood populations in northern California. [1]

A lot of work was done in the 1970's and '80's by astronomers and physicists to 'hack' Eastman Kodak scientific film, or plates as they were called. (Once you move past "point and shoot" film, you get into the realm of plates, 4"x5" trays similar to old-timey 1880's cameras.) Things like Kodak I-Z. One technique was to hypersensitize the film by bathing it in Ammonium Hydroxide [2]. Lawrence Livermore had such an appetite for IR-sensitive film with their laser work that they set up their own production process for hypsersentizing Kodak scientific plates. Another was to supersensitize them with acetic solutions getting film sensitivity in the >1500nm range [3]. This seems to be the limit of our knowledge for traditional chemical film processes.

Modern DSLR's have sensitivity up to 1600nm. Nikon worked with NASA for some of their special DSLR's [4].

One of the cooler things I saw was a University of Florida paper in Nature that used IR-OLED's to upconvert IR to visible light through a lens adapter achieving sensitivity from 400nm to 2000nm [5].

Beyond 2000nm you get into the MWIR range and FLIR devices take over.

[1] https://books.google.com/books?id=HZUTCgAAQBAJ&pg=PT129&lpg=...

[2] http://www.osti.gov/scitech/servlets/purl/4442636/

[3] https://books.google.com/books?id=nlftCAAAQBAJ&pg=PA259&lpg=...

[4] http://eol.jsc.nasa.gov/Collections/NearIR/IR_Intro.htm

[5] http://www.nature.com/articles/srep05946

People who dig to understand and create stuff like this are just amazing.

> but any wavelength of light you absorb (not just IR) will heat you up

Thanks - this is the bit I was un-/miseducated about. When we were taught about radiation in high school, I suspect my young mind concluded that since infrared and visible light were mutually exclusive on visibility, the same applied to heating. To this day, I thought infrared → heat and heat → infrared.

Do you have do develop those films in the freezer? A normal dark room is not really dark at those wavelengths, even if you turn the red lamps off, right?

Walls are transparent to FM (~100MHz) radio, so you won't see anything.

WiFi is closer. High microwave is probably what you want here.

And of course, this already exists. It's called radar. Haven't seen any radar "photos" though. Interesting if that's indeed possible.