[Laser] laser blowed XE2AT

[Art]

I wish I had a better answer for the blown lasers at XE2AT. Some other 
Ramsey users report no laser problems.

I checked Laser Sam's FAQ. He recently added a section about controlling 
laser diodes with single resistor current limiting driver circuits. He 
added that he had actually evaluated some laser diodes taken from laser 
pointers that had threshold current at 15 ma and an operating current at 35 
ma, which seems a very wide margin. Sam suggested that there might be a new 
process allowing these lasers to be driven properly with a single resistor.

I contacted Sam on usenet, and asked for more info.

Among my questions were "has any reputable laser diode manufacturer ever 
suggested that their laser diodes can be properly operated with a simple 
series current limiting resistor". His answer was NO.

After some more discussion, Sam's own conclusion was that the lasers should 
be driven by a proper driver, not with a single current limiting resistor. 
Sam also stated that PWM at 18 HKz was not very demanding of the driver and 
that it needn't be a complicated driver circuit.

I know many laser users operate laser diodes in this manner and have no 
problems. I also know alot of laser pointers come from the factory with 
this sort of driver.

But, I think Sam's comments carry alot of weight and he suggests the use of 
a proper driver.

Regards,

Art