Mysterious light from 520nm diodes(pic heavy)

[Nexgen]

Recently when using 520nm lasers I noticed that there's coming light over 540nm.

Is it safe to observe, because my ep don't block light over 540nm.

It's clearly seed in the right laser here:

 

[Radim]

Strange. Seems to me to be spontaneous emission of the diode. Not laser light. Let's see what others will say. Diachi and Oliver? Is the laser damaged? Battery ok (not drained)?

 

[Nexgen]

Strange. Seems to me to be spontaneous emission of the diode. Not laser light. Let's see what others will say. Diachi and Oliver? Is the laser damaged? Battery ok (not drained)?

Everything is fine with both lasers. Batts fully charged.

 

[Radim]

I do not know. Does speckle pattern looks like laser? I mean if you compare yellow dot with normal led light, you should see difference as laser has kind of little bright "stars" in it changing as you move your head. Led should not have them.

 

[Nexgen]

I do not know. Does speckle pattern looks like laser? I mean if you compare yellow dot with normal led light, you should see difference as laser has kind of little bright "stars" in it changing as you move your head. Led should not have them.

It's very dim. I'm not seeing speckle through my goggles.

 

[Radim]

Seems to be spontaneous emission. Diodes do that sometimes. The question is, whether it is normal - if there is 520 nm output should be major. Still if there is no 520 nm output there is something wrong - diode might be damaged by back reflection, it was ran for too long or something. Than if there is damage like those mentioned diode might behave like normal led or stop working at all. There were some cases on LPF reported, where red diode laser hit itself reflected from mirror or window and damage made the laser diode to be very dim and likely not laser anymore. Some weird radiation was even observed from other diodes what I have read here.

Let's see what more experienced laserists will say.

Edit: I see the pictures on computer now. I saw them on mobile before and sun was shining on the screen - so I did not recognized there are likely through glasses. In that case this might be (and very likely is) fluorescence. It happens with my strong (high OD 6+) Univet goggles. Laser dot is (almost) invisible in that color, just fluorescent light similar to how it looks on your pics (yellow/orange). It might be partly green (original laser) and parly yellow-red (fluorescence spectrum) composed to look like something yellow. In that case it is normal. Some strong glasses reduce the laser light to the level you see only the fluorescence which is able to pass glasses (therefore the similar colors what you see through glasses).

 

[paul1598419]

This could also be a fluorescent light that is being emitted by the goggles. If so, it is not a problem to your eyes as we have seen this before. It isn't collimated or even in phase.

 

[Emialias]

from what experience ive had with 520s and a post i saw earlier, 520 diodes seem to have a tendency to leak orange and blue light in very small amounts. someone on LPF here saw something similar when they pointed their 520 through dark orange glass and left an orange output through it.

 

[paul1598419]

I've noticed that with the glasses I wear for severe myopia, if my head is turned slightly, a laser dot will have red and blue artifacts on the left and right of the dot. It is caused by the glasses and not the laser, however.

 

[CurtisOliver]

It is fluorescence. No spontaneous emission here. Shine your greens (532 or 520's) on some red surfaces and they fluoresce the dye. It often appears lime green to yellow.

 

[paul1598419]

That was my thought as well. I've found this same type of emission from my googles when I point a laser at them. Not wearing them, of course.

 

[CurtisOliver]

Yep, I've observed this on multiple red items not just goggles.
Lol, you are too wise not to try it with the goggles on.
Many seem to forget that green can fluoresce as well a the shorter wavelengths.

 

[diachi]

Yep, I've observed this on multiple red items not just goggles.
Lol, you are too wise not to try it with the goggles on.
Many seem to forget that green can fluoresce as well a the shorter wavelengths.

Red can do it too, but the emitted light would likely be in the NIR part of the spectrum and as a result invisible. Seems to be less common even then though.

 

[CurtisOliver]

Yes, that is correct Diachi.