I need a sensor to sense if an object is present through 1/4" piece of plexiglass. Does anyone know if this IR sensor would be a good choice. I was hoping to find something a little more cost effective because I will be using 20 total. If anyone has an idea of something that might be another choice, I would love to hear it.
You may have to buy one and try it or someone who has one give it a try. If the sensor is right up against the Plexiglas then I think it would work. If the sensor is back a few inches or more the Plexiglas may reflect enough of the IR to either give false readings or reduce to sensitivity. This is just speculative so it does need to be tried.
Thanks. The sensor is going to be flush with the plexiglass. I found these, I think I will give these a try since they are a little cheaper.
Plexiglass blocks IR! You might get enough transmission for your purposes, but I doubt it. That’s why germanium is used for IR lenses.
Leon
leon_heller:
Plexiglass blocks IR! You might get enough transmission for your purposes, but I doubt it. That’s why germanium is used for IR lenses.
Plexiglass does transmit IR, as my “opaque” plexiglass cover over my IR remote repeater attests. There are tech papers on the net, and vendors publish specs that describe the degree of transmission. Here is a sample from one manufacturer:
Standard Plexiglass, which is probably what the OP is using, doesn’t transmit IR at all well. He is using 1/4" thick material, I doubt if he will receive much.
Leon
I will concede that there may be some plexiglass that doesn’t pass IR well, and I don’t know what comprises “standard’ plexiglass. But, I just took two 1/8” (didn’t have 1/4" around) clear plexiglass sheets bought at the local hardware store, and stacked them. I then pointed my IR remote at my camera at a distance of 3’ feet and noted the intensity of the beam. After placing the two sheets directly in front of the camera, I couldn’t discern a difference of the light intensity. Clearly, there had to be some attenuation, but it wasn’t noticeable to me.
So what I’m saying to the original poster, is that it is possible, but you might have to choose your plexiglass. Try the stock at the hardware store first, though.