Originally Posted by MonsieurM
, following up on your idea of infra red, i would suggest a laser pointer instead
I have a 1w 445nm, and a 65mW 532nm laser, but those infrared lasers are quite dangerous. I did hit the rochelle crystal with the 445 and got a slight dc voltage. It's interesting that the crystal does not heat up or burn with the 1 watt laser. The green laser is actually a ir laser that shines through a crystal to produce 532nm, although I don't think you want to ruin a nice 532. Ir lasers are pretty cheap although dangerous. My 445 can cause permanent blindness just from a reflection in less time it takes to blink your eye.