Did I ruin my laser

[GSS]

Yes that is dim but there is always a use for it from a cat toy or just taking it apart to see what makes it click

 

[Gabe]

Haha, waking up this morning it's still funny... I'm just glad it was part of a parts kit so I'm only down $25 for the diode/module and not $100 for everything!

 

[Hibro]

It is weird but I don't expect a reflect red laser will kill itself (as they are usually under 300mW) ? :thinking:

 

[Gabe]

It is weird but I don't expect a reflect red laser will kill itself (as they are usually under 300mW) ? :thinking:

Mine was just over 300mW, easily enough to burn the dye when focused back onto it. Chances are OP's laser was around 200mW if I had to guess

 

[HTPOW]

Are you use the laser pointer more than 30 seconds? Laser diode may be damaged。

 

[Benm]

the laser has something called a laser diode, which emits the light from a very small point, however the light does not come out perfectly straight, it diverges and makes a large circle, so the laser has a lens to collimate it into a nice, straight beam. when the beam goes back in (becuase you pointed it at a miror) the lens then focuses the beam right back onto the diode, breaking the laser diode. this is definitely what happened to your laser.

It is possible, but i wouln't say definite.

Reflecting a laser beam from a diode laser back into it can certainly do damage or destory it.

However, at 1 meter distance the beam would be about 2 mm wider than when it left when it gets back to the laser (assuming 1 mrad). Practically this means that a fair amout of light would not make it back to the laser diode since it hits the edge of the lens or output aperature on the way back.

If the malfunction happened exactly at the moment the reflection hit it, i'd say it's plausible that it caused the failure, but would not rule out coincidence.

 

[micheal rosen]

It is possible, but i wouln't say definite.

Reflecting a laser beam from a diode laser back into it can certainly do damage or destory it.

However, at 1 meter distance the beam would be about 2 mm wider than when it left when it gets back to the laser (assuming 1 mrad). Practically this means that a fair amout of light would not make it back to the laser diode since it hits the edge of the lens or output aperature on the way back.

If the malfunction happened exactly at the moment the reflection hit it, i'd say it's plausible that it caused the failure, but would not rule out coincidence.

These single mode reds have very, very low divergence. But the main thing is that the beam hits the diode at almost the same exact size as the emmiter, which, in single mode reds, is SUPER small (not sure of the exact measurements but it's on the order of micrometers.)

 

[Gabe]

It is possible, but i wouln't say definite.

Reflecting a laser beam from a diode laser back into it can certainly do damage or destory it.

However, at 1 meter distance the beam would be about 2 mm wider than when it left when it gets back to the laser (assuming 1 mrad). Practically this means that a fair amout of light would not make it back to the laser diode since it hits the edge of the lens or output aperature on the way back.

If the malfunction happened exactly at the moment the reflection hit it, i'd say it's plausible that it caused the failure, but would not rule out coincidence.

These single mode reds have very, very low divergence. But the main thing is that the beam hits the diode at almost the same exact size as the emmiter, which, in single mode reds, is SUPER small (not sure of the exact measurements but it's on the order of micrometers.)

What Rosen said. Its not likely OP's laser was over 200mW, but I'm pretty sure that's what happened because, note the video I made, I ruined my laser trying to disprove it. However, I don't thing it's possible this happened to OP's laser on accident, he had to have been intentionally aiming it into the lens. I just don't believe it could've been a coincidence considering how close the symptoms on his laser are compared to mine.

 

[micheal rosen]

What Rosen said. Its not likely OP's laser was over 200mW, but I'm pretty sure that's what happened because, note the video I made, I ruined my laser trying to disprove it. However, I don't thing it's possible this happened to OP's laser on accident, he had to have been intentionally aiming it into the lens. I just don't believe it could've been a coincidence considering how close the symptoms on his laser are compared to mine.

Accidental lens sweeping is fairly easy. It was an accident for me, I was moving the beam around with a stainless steel plate and accidentally sweeped the lens for a very short time and LED'ed it.

 

[Gabe]

Accidental lens sweeping is fairly easy. It was an accident for me, I was moving the beam around with a stainless steel plate and accidentally sweeped the lens for a very short time and LED'ed it.

Really? I tried sweeping for a short glance and it did nothing. Only after it was on the lens for around a whole second did it cut

 

[micheal rosen]

Really? I tried sweeping for a short glance and it did nothing. Only after it was on the lens for around a whole second did it cut

Interesting! Maybe the diode's they use are just crap as well. What type of lens were you using?

 

[Gabe]

Interesting! Maybe the diode's they use are just crap as well. What type of lens were you using?

Three element, but keep in mind there's a whole bunch of crap on it and the AR coating is worn off

 

[micheal rosen]

Three element, but keep in mind there's a whole bunch of crap on it and the AR coating is worn off

Yeah. I had a single element lens that those cheap 303's have, it was fairly clean and I think was pretty clear as well.

 

[Benm]

The emitter area in a single mode laser is in the order of a wavelength, so it would be a bit under a micrometer for a red diode. Divergence also depends on the emitter area depth, but that's another story.

To destroy a laser diode by a reflection requires that reflection to go -exactly- back to where it came from. This is obviously possible hitting a good qualtiy mirror at an exact normal angle. If you wanted to experimentally reproduce this you could quite easily do so (difficulty comparable to aligning 2 color mix lasers to have the dots overlap a meter away or so).

Doing it by accident would be more diffcult, but not impossible.

One issue that is important here is how hard you are driving the laser: If you are driving it under half it's absolute momentary maximum output power, the laser diode can handle a brief full reflection. If you are driving it near or even over absolute maximum optical power a reflection can kill it quickly.

I know we all like to drive laser diodes hard to get a good result, often exceeding absolute maximums from the manufacturer. This can cause a reflection to quickly kill a laser diode. If you kept to the CW output power listed in the datasheet it will never happen, and virtually all laser diodes can take a 100% back reflection for an infinite amount of time.