Saturday, August 25, 2007

possibly some bad news about my new laser

Two days ago, I received a high-powered laser after winning it in a contest. It could pop balloons, light matches and sting my skin. This is consistent with the abilities of a 75 mW laser. Yet none of these things are happening anymore.

From what I've been told, lasers often have a high initial output that gradually stabilizes. This is known as the burn-in period. However, I have reasons to suspect the laser is actually defective.

The inverse-square law means the apparent brightness of a laser is proportional to the square root of its power. Because my laser is now only slightly brighter than my 5 mW one, the output is probably around 15 mW at most. In an ironic twist, my originally overpowered laser is now underperforming. I did some research and have an idea of what happened.

Caution: technical details ahead

Green lasers have four main components: the potentiometer, pump diode, and Nd:YVO4 and KTP crystals. The potentiometer controls the voltage of the 808 nm pump diode. The Nd:YVO4 converts the light from the pump diode into 1,064 nm light. The KTP then doubles that into the 532 nm green light we see.

The potentiometer in my unit was likely turned up to the maximum. This would account for the high initial output. However, the crystals likely overheated and quickly burned out.

In any case, I'm heading back to Berkeley tomorrow. I know there are laser labs in the physics department. Perhaps I can find someone to take a look at my laser...

Currently listening to: Country Mountain Bluegrass by Green Hill Music

No comments:

Post a Comment