Photoelectric sensors

I am preparing a waste separating machine for which I want to detect plastics and metals out of other Biodegradable wastes. I have read that photoelectric sensor can be used to detect both of the above simultaneously. Can anyone share with me any of their experience working with Photoelectric sensor on arduino. Any sort of Help will be appreciated..! (Related to Photoelectric sensors..) https://www.ia.omron.com/support/guide/43/introduction.html