IR diffusing materials

I need to create a box that emits IR light evenly across one face. I’m going to put IR LED’s inside the box, but I need to find a good way to diffuse the light so that the side of the box which lights up does so evenly across it’s surface.

I’m experimenting with different materials now, but wanted to see if anyone here had some ideas and/or experience with this.

I’ve done some of this for a customer’s IR project a while back. I ended up sandblasting both sides of a piece of glass, and it worked pretty well. For really, really good diffusion, use sandblasted white glass. You can get a piece of glass at the hardware store and sandblast it yourself for almost nothing.

Interesting. Isn’t glass, generally, opaque to IR?

It depends on how truly IR it is. If you’re using IR LEDs, they’re actually considered “near IR” and act much more like visible light than something closer to 1000 nm. Most IR LEDs are around 850, but you can get some around 940 for a little more money. I’ve got some of both if you want to try them.

I had a leftover IR “spotlight” from a project a year or two ago that’s sitting on the shelves in the ERP lab. It is a hinged wooden box, roughly a 5" cube, with a reflector inside and a switch on the outside. Don’t stare directly at it. I believe it is at 850 nm. You’re welcome to grab it if you want to experiment without having to build something first.

I think you are thinking of UV. Expensive window glass is IR blocking for energy reasons, and called Low-E glass. I think plain glass attenuates, but does not block UV and has little/no effect on the IR bands. You could test my theory in a few seconds with a remote control, any window or piece of glass, and your smartphone camera. Shoot the remote through glass and see if you can see a faint purple dot where the IR LED is via your camera.

Logan is, of course, correct. What I said is true of Low-E glass only.

as most of what everyone is tossing out there is beyond me, perhaps thick plexi as its more durable than glass. i know if you opaque the sides it will “glow”. opaquing actually doesnt even require sandblasting as the sides will opaque as soon as you cut them with a saw. just a thought…