I have a garage door opener that allegedly senses pressure, in case of an object in its path, and reverses. I say "allegedly" because the other day it tried to self-destruct when it wouldn't reverse for a wheelbarrow in the way. Ten hours later, it is back in functional condition, and the door looks pretty good. The opener has neither an obvious brand name, nor any obvious way to adjust the pressure sensor.
Being a cheapskate, I'd rather add an optical circuit, so that if a beam across the path of the door is broken by an object, the door won't activate at all. The electronics of this is simple, but I haven't ever implemented an optical circuit like this, so I'd like any experienced advice as to what is the best choice of optics. Should it be infrared, or visible, and if visible, is one color better than another? How much LED do I need (intensity), and any other gotchas which might affect a design like this?
Thanks in advance for any suggestions.