Glad to hear of your success.
Sadly, my attempts to realize the polarized system did not work. Diffusely reflective materials (eg. paper, felt, clothing, etc.) randomized the polarized light and rendered it visible to the sensor within the 1 to 2 m range. Beyond that range the retro-reflector worked as expected up to about 15 m with or without the polarizing filters. The only thing the polarizing filters did was allow the sensor to ignore mirror like surfaces.
If your target were 2 to 15 m away (6 to 50 feet) you could use a dot of retro-reflective tape as the bulls-eye and it wouldn't matter what was around it. Then you wouldn't need latching but if your distance is 2 to 3 feet then it sounds like you have found the best solution unless you intentionally attenuated the beam by passing it through some darkish plastic or glass filter.
talkingrock wrote:Dear Gordiegii,
Thanks so much for your reply. I now have the break beam sensor up and running. While I am not schooled enough in light to understand your prior postings re polarized light options with this device, I have observed the following:
My project attempts to use the beam essentially to tell if something (that the beam is focused upon) has moved. This proved quite tricky. The target is about 2 - 3 feet away, and must respond in all potential lighting situations, from full sun to pitch dark.
I had assumed that I could make, say, a circular target (3 inches), with a reflective surface for the bullseye, surrounded by a light dispersive material. I found out that that did not work. In fact, the opposite has worked better than I ever expected. Namely, I have a little black rubber dot (3/4 inch dia.), surrounded by essentially a holographic surface (which was on the back of a 99 cent kid's compact mirror I picked up at the discount store). Pure eureka (at least for me) !! It works perfect. When the targeted object moves, the beam moves from the black rubber to the more reflective surface (the dot when hitting the holographic surface is way brighter), then unfailingly triggers the LED. I will need a latch down relay I am sure eventually, but this was the first test of the system.
Again, thank you so much. Feedback on surfaces is always welcome.
talkingrock