will dead diode produce a dot

[aktopjian]

Title kinda says it all. Will a dead diode produce a pretty visible dot at 15-20ft? When I hook up a red to the driver I have to the red is very bright compared to the blue. If there is a little smoke from a cigarette or some incense you can see the beam of light from the blue.

[Admin]

Depending on the damage done, maybe.

If you fed it 30A - probably not. That kind of abuse is likely to blow the facet off or at least destroy the bonding wires... for spark/slight overcurrent conditions where the substrate has been fractured but not cleaved, you can still get a weak dot most of the time.

[mpoulton]

Title kinda says it all. Will a dead diode produce a pretty visible dot at 15-20ft? When I hook up a red to the driver I have to the red is very bright compared to the blue. If there is a little smoke from a cigarette or some incense you can see the beam of light from the blue.

Doesn't sound dead, but doesn't sound normal either. All my dead ones are DEAD. No light, not even an incoherent glow. I have run across a few "sick" ones that lase but only produce ~50-100mW at 1A. If your blue diode were working correctly, it would be MUCH brighter than any comparable red laser. What current are you running? You need at least 250mA to get a real beam.

[mpoulton]

Oh yeah, the other question: Does the "dot" you see have laser speckle? Sometimes damaged diodes will produce blue light but not lase (just like a normal diode operating below threshold), and the result is a weak blue dot that does not speckle because it is not monochromatic enough. If you have speckle, then your laser is working... maybe just not very well.