aww, so the the sensor is really tiny, the lens is there to make it seem a little bigger.
i can use any color light that i can get an LED to produce. I'd probably like to use something infrared.
i was thinking a triangle shaped sensor would be good for an optical guitar pickup. i think they usually use a regular photodiode, but i don't see how that would work.
here, i'll draw a picture:
the triangle is the sensor. the line is a string. the light source would be from out of the page.
see, if the string moves up, it will shadow more light from the sensor, if it moves down, it will shadow almost none.
now i need to make friends with someone at national semiconductor i guess.