Sunday, 28 June 2009

IR Webcams and Night Vision

One thing most people don't realise about CCDs (the light sensors in the vast majority of digital cameras) is that they are very sensitive to infrared light. Sadly this is only near infrared, 800-1000nm wavelength, not thermal infrared, but is still great fun!

Modification of a webcam to see at these wavelengths is generally very simple, you simply have to take out the filter which cuts out the infra red light...
Then replace it with a filter which only lets infrared light through, household examples of this are exposed colour film negatives, a floppy disk platter, magnetic tape from a cassette and coke...
You can see the IR filter in the centre, it's the greenish glass, and my replacement filter cut from a floppy disk to the right.

Once converted the webcam will act like a black and white camera (the filters used to give individual pixels different colour sensitivities are transparent to infrared). The sky appears dark, plants a brilliant white. Fluorescent lights produce no infrared light, but the glow from your oven lights up the whole kitchen! Infrared is particularly suited to cloud and landscape photos as it is less affected by haze.
At some point I'll get round to posting a timelapse of the sky in infrared, it looks amazing!

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