I’m building a table with 4 holes, that is covered with glass. Underneath the table is a camera, that captures a snapshot when all 4 holes are covered with paper. The idea is that it can only take a snap shot when there is paper covering the holes, so that it doesn’t capture the ceiling etc.
I’m thinking to use infrared distance sensors (http://uk.rs-online.com/web/p/photoelectric-sensors/6666564/) to check whether there is something placed on the glas, but I’m not sure if the glas itself would influence the distance so much, that I won’t be able to tell the difference with or without paper.
So my first question is: Do you think infrared distance sensors would work?
Secondly if it doesn’t, is there any better way to check for paper on top of the glas?
I hope it makes sense.