Laser Diode Driver Safety

Laser diodes in the 1-5W range (common in laser engravers and cutting heads) are permanently destroyed by current spikes from switching power supplies or ESD. Here's the correct driver design.

The fundamental requirement: constant current drive with fast overcurrent protection. The LM3414 is a constant-current LED/laser driver IC rated to 1A. For higher current, the NZXT or a custom op-amp feedback design around a power MOSFET works.

Electrostatic sensitivity: a laser diode can be destroyed by as little as 10nJ of ESD energy — far below what a human can feel. Always handle laser diodes in an ESD-safe environment, with a grounded wrist strap. Store them in anti-static foam. The anode and cathode should be shorted together during storage and handling.

Interlocks: any laser above Class 2 (1mW) requires an interlock system that disables the laser when the enclosure is open. A safety-rated door switch (not a cheap microswitch) in series with the power supply enable line is the correct implementation.