Such experiments are so simpel but fun. If one does not want to wait month for some order from China, it is possible to make a fine photodiode by cutting the top of an old TO-3 transistor or use a led. Any semiconductor reacts to light and works as a solarpanel / detector. Thanks for the video.
Your quiet and interesting character. Wish you my neighbor. Try putting an incandescent light bulb near your beam path for more action and perhaps bats after the bugs. I must say near the end I heard something different @ 20:54+/- that sounded like a wet one.🤣😷Toot&Tell It. I use to point a laser at annoying street light photocell when I had the telescope out.
You can do something similar to transmit audio if you vibrate the laser with a speaker. You can use a cheap solar garden light as your detector. You can use a mirror and sunlight instead of the laser.
Have you considered using a mirror (or two) to reflect the light to and/or from it's source? I realize there will be some loss and/or divergence. Just an idea for experimentation. Also if you can acquire an inexpensive rifle scope to experiment with. Toy or minoculars also.
I forgot to mention that the lenses from a pair of inexpensive polarized sunglasses might be useful for your experiments. Also infrared filters from old webcams.
