Laser diodes and you
I know some of the people who read this blog (or who will see links to this post on Twitter) are into laser diode projects, so I thought I'd throw out some of the lore I've acquired on the topic. Laser diodes... 1. ...are current driven devices: Always drive them as such, being careful to limit the current through them to some relatively safe value. 30mA is not an unreasonable guess; as they age the current required for the same output power will increase. 2. ...aren't very laser-like: Don't expect a laser diode to put out a tidy little dot of light. That requires some optics. As the current pushed through a laser diode goes up, the efficiency of the device increases, and the divergence angle of the beam decreases. The beam tends to project an ellipsoidal shape on a perpendicular surface; the larger of the two dimensions will change more as the current goes up, while the smaller dimension won't change much at all. This is why laser pointers do not project a