reading reflected laser light

Another post reminded me that LEDs used as photodiodes are very wavelength sensitive. So, you could try an orange or red LED as a photodetector for your green laser.

LEDs are most sensitive to light about 50 nm blue-shifted from their respective emission maximum, so look for an LED with emission maximum of around 610 nm, to match your 562 nm laser line. Try several different LEDs as their efficiency varies greatly.

See How to Use LEDs to Detect Light - Make: