Been using Red LED as sensors and they do provide some voltage however that would require optical setup which is a problem to meUsing LED as sensor will greatly reduce ambient noise, unless you just have band-pass filters laying around. Take a clear LED and connect it oscilloscope probe. Ambient light gives almost no response. Then shine a laser on it and see a voltage of 1.5 V or more.
This is a fascinating project that I did about 30 years ago with HeNe source (and no google access). However, as Paul pointed out, I doubt that it has use as practical tool.
"Information Unlimited" sells kits for this device. I only mention this because I look forward to hearing LPF members opinions of this company.