Infrared Transparent Material SLA

hal_4 · 2017-09-08T14:34:00.000Z

I am currently designing a remote control for a client. It contains IR emitters for communicating with the device. The emitters will be covered by a piece of plastic like the ones commonly found on TV remote controls (example image attached).

Does anybody have any experience or know if Infrared waves can pass through any SLA materials?

Many thanks,

Hal

chanman · 2017-09-09T01:36:11.000Z

Not much for SLA material, but polycarbonate has good transparency to IR and can be printed ff printers.

hal_4 · 2017-09-09T11:19:45.000Z

Thanks.I imagine its going to be a trial and error process with SLA!

shahramrobotics · 2017-09-09T15:23:43.000Z

The plastic in front of the IR transmitter is an IR band pass filter. If you use an SLA print it will not act as one, although the IR light WILL go trough it.
The reason they use that piece of plastic in front of the transmitter is that the IR LED inside is a wideband IR (cheaper) and is not fine tuned for exactly 850nm or 900nm, it will emit from 700nm all the way to 900nm for example. But the fine tuned IR LEDs don’t need one, that’s why some remotes don’t have that piece of plastic, and the IR LED is half way out.

MDVolle · 2017-09-19T06:10:28.000Z

IR will pass through many plastics but there are two factors that could impact your printing.

First, pigmented plastics vs dye based color - the basically transparent plastics can be dyed to almost visually black without stopping the IR light.

Plastics that are based on an opaque material or even “clear” plastics with opaque fillers (for strength or color) will block the IR.

Second, layers/warps/distortions in the plastic will change the beam shape and quality of the IR emitter - stepping internally or externally on the part could diffract the beam inconsistently - usually diffusing the “beam” into a general “flood” or wash of light - this may work perfectly at short range but be useless at long range.

I have done a lot of work with IR and it isn’t magic - to get good optical performance in IR you need the same qualities of flat, parallel and uniform surfaces in a clear (no voids/ripples/solids) material as you would need for visible light.

The deep red filter or actual IR filters over remotes are almost completely about the RECEIVER not the transmitter - they are filtering out light that doesn’t have any useful information so the receiver won’t be overwhelmed by the unfiltered light - this can improve sensitivity quite significantly. For the transmitter, its about preserving the optical performance of the emitter and mechanically protecting it.

Just my opinion…