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  • Infrared Digital Camera - the Real Way

    Unsure if this was meant to be “850” nm or “85”nm so I’ll answer for both (even though it’s an ancient question now).85nm is pretty deep into the UV - this is an old question so you’ve probably discovered already that CCD sensitivity is negligible in the UV, especially that far out. Special coatings called “lumogen” coatings are used to enhance sensitivity - these phosphoresce in the presence of UV, converting the UV to visible light. While you could filter out other frequencies and give it a try, 85nm sounds pretty specific and suggests a scientific application.If you’re looking for 850nm, that’s still in the “near IR” region - close to visible light. If you need precision you’re probably going to want to remove the filters from the camera and find a compatible scientific narrowband fi...

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    Unsure if this was meant to be “850” nm or “85”nm so I’ll answer for both (even though it’s an ancient question now).85nm is pretty deep into the UV - this is an old question so you’ve probably discovered already that CCD sensitivity is negligible in the UV, especially that far out. Special coatings called “lumogen” coatings are used to enhance sensitivity - these phosphoresce in the presence of UV, converting the UV to visible light. While you could filter out other frequencies and give it a try, 85nm sounds pretty specific and suggests a scientific application.If you’re looking for 850nm, that’s still in the “near IR” region - close to visible light. If you need precision you’re probably going to want to remove the filters from the camera and find a compatible scientific narrowband filter appropriate to your camera. This will be easier with a DSLR than a cheap point and shoot.

    For all the folks curious about “why not a red filter?” and similar, it’s simple but counterintuitive: infrared and red are still different colors. What you’re looking for in a filter is the spectral response for the colors you *can’t* see. Lee 181 has a very low response even in blue, tapers off towards the UV and is mostly flat and nontransmissive for most of the rest of the spectrum until just at the far edge of visible red when it suddenly starts to spike upwards. It is this spectral response which makes this filter work - not that it is “blue” but that it is transparent for IR.

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