Help with building an outdoor IR webcam enclosure...

April 8, 2011 11:47 AM

Ok this is may sound like a weird one... Basically I'm building an outdoor enclosure for a panning/tilting webcam that has IR lighting built into it. It was going to be all sides Lexan, to keep things simply and neat looking. I learned, midstream of course, that the Lexan/Plexiglass/glass all reflect IR light like crazy so you just see a beautiful ring of IR lights and not what's outside the box when viewing the stream. I'm told a UV filter might work, embedded in the front of the enclosure. The challenges are:

- the front of the enclosure is about 6"x6", so the bigger whatever solution I use is, the better. Seems most UV "filters" are for camera lenses (of course) so are somewhat smaller and would limit viewable area - The camera itself (not the enclosure) moves, so would be nice to have more coverage than just a single front facing UV lens (or one on each face)

Is there any other solution, like a UV film, or something similarly outdoor ready that could be applied to, or used in place of, the outward facing Lexan/plexiglass panels? It doesn't need to withstand a hurricane, more like "oops it started raining and I'll run out and get it when my coffee is done".

This is the camera model, btw. Love it, great price ($99 at amazon), just want to let it roam about my property a bit more http://foscam.com/Products_List.asp?id=173

Thanks for any and all suggestions! (Which may include "hey goofball you may want to check out this other model that works much better for your situation")

Thanks!

posted by rtgoodwin to Technology (3 answers total)

I'm not sure that polycarbonate is much worse than glass in its transmission or reflection of IR, in fact this transmission spectrum suggests its quite good. IR Led's emit at about 950nm and the transmission should be around 90% at that wavelength. The refractive index of polycarbonate is about 1.58 which is a bit higher than glass. Therefore the reflection from each surface will be a little worse (my calc says 5.1% off each surface). So what you need is an anti-reflective coating on both surfaces of the polycarbonate. You're looking for a transparent material with refractive index of as close to 1.26 as you can get.

There are PET Anti-Reflective films made for the LCD screen business (3M makes them). I'm not sure if you can buy a small piece, but that would probably work quite well.

Fluoro-polymer front sheet material for solar panels would be ideal. In fact, you could use it in place of the polycarbonate (its flexible so you'd have to stretch it over the front like a drum skin). Maybe you could score a small piece as a free sample from Dupont.
posted by Long Way To Go at 1:56 PM on April 8, 2011 [1 favorite]

Best answer: You could extend the box in front, like a hood over the lens, and omit the front pane so
there is no reflective surface to devil your view.
posted by the Real Dan at 2:04 PM on April 8, 2011

Response by poster: Long Way To Go: great answers! Will research. It's actually been quite fun learning from this particular mistake :) I think I even have an anti glare screen left I could cut up to see what happens.

the Real Dan: Yes! I'm thinking about that too; would definitely work in a pinch. The reality is I shouldn't have it out there for long periods of time anyway; it is electronics after all, and the elements will take their toll.

I think one way or the other one of these solutions will get me there. Ask.MeFi is amazing!
posted by rtgoodwin at 7:50 PM on April 8, 2011