Can IR light from an Infrared LED pass through semi-opaque acrylic?
The only (and thus, the cheapest) way I can think of sensing this distance without cutting holes in the upper piece of acrylic is to use an IR transceiver on the circuit board and connect this to the white LED. Would this work? I'll be using .25-inch white acrylic if that makes a difference.
Any assistance that you can provide is greatly appreciated.