Infrared Webcam HOWTO

Geoff Johnson writes "Some of the Slashdot readers may be interested in this page I put together. It describes how to make an ordinary webcam see in the near infrared waveband."

Comments

duh

[oliverthered]

Let me guess, remove the IR filter from in-front of the lens.

Re:duh

[oliverthered]

You don't need to for 'night vision', which is what I expect most people will be interested in.
Full colour (maybe a tiny bit washed out because of the extra IR) during daylight, and at night switch on the IR light and you've got an IR camera.

Near IR isn't that interesting, except humans cant see it, what would be cool is if the chips could pickup far IR so you could see heat.

Re:duh

[huge colin]

Cadillac's system was actually a Barium Strontium Titanate (BST) module, developed by Raytheon. It required a thermal differential in the scene from frame-to-frame to be able to see anything, and thus a "chopper" wheel (a rotating slotted disc) had to run in front of the detector. The picture would smear and was generally low-quality. The module used by Cadillac was also rather low resolution (160x120, I believe).

The alternative to BST is microbolometer technology, developed by Lockheed Martin / BAE Systems and others. A microbolometer array consists of vanadium-oxide bridges that vary their resistance when exposed to thermal radiation. The scene will occasionally need to be "shuttered" (i.e., zero all the pixels against the back of a shutter mechanism to cancel the thermal drift that creeps in over time.)

Unlike light-amp, true thermal imaging allows you to see in complete darkness. And unlike projected-IR, it isn't limited in range by any kind of IR-transmitter. And unlike either of those technologies, it allows you to very quickly find humans (or other mammals) in a scene, and it allows you to see where things used to be by the heat-shadow that they've left.

Can it see through clothing?

[Anonymous Coward]

Cause I'd really like to take my PC to the beach and get webcam shots of da honey's.

infrared wecam!

[Anonymous Coward]

that's just fantatic!

cached link of video if it dies.

[Organized Konfusion]

http://homepage.ntlworld.com.nyud.net:8090/geoff.j ohnson2/2004-08-08.avi

Not all cheap webcams have filters.

[OneDeeTenTee]

If you're lucky the webcam won't have an IR blocking filter.

You may want to check it with a remote (or just put your IR passing filter in front of it) before you take it apart.

OK.....

[mr_z_beeblebrox]

So the article details a cool hack, props. What I want to know is.....why was I able to download the 6.9 MB AVI file at the end. Isn't his server supposed to die or something? I can never download the files referenced by a /. link. Is something wrong?

Re:Infrared Technology and the Chinese Threat

[budgenator]

Actualy this is pretty much WW-II style technology, the old Sniper-Scopes used active IR like this web-cam mod. Now the problem is passive IR is so common firing up an IR illuminator is like painting a bull's-eye on your forehead. It's so common, we put blue filter on our flashlights to block the near-IR and IR output; visible light is less damgerous the IR at night!

alternative approach

[tverbeek]

Or just accelerate your webcam enough (toward the object you wish to photograph) to blue-shift the infra-red into the visible frequencies. Put it on a really-high-speed ferris wheel or merry-go-round and synchronise the snapshots to its rotation if you want to keep it "stationary". Compensating for the doppler shift in the signal from the camera is left as an exercise for the reader. But no disassembly or modification of the camera needed!