532 Collimated IR output

[grainde]

Great pics KapHn8d! Feel free to embed the images if you like.

I should finally convert my 20D to IR... :beer:

 

[sarbanes]

Which is the/a common wavelength that is absolutely invisible to the human eye. Would love a 5W ver for some wood litho, but I don't want to pull apart any 532's I no longer have.

 

[AJ_Dual]

It would seem to me that if the IR is aligned with the visible 532nm or other DPSS frequency, then that's actually safer, since you've got your normal visual aversion to look away or blink.

I always figured if the passthrough IR was a safety problem, it would be either if/when there's still significant IR output that's not eye-safe, but is below the threshold for the DPSS crystals to convert and re-lase, or if said IR was well collimated, but off axis from the main visible light wavelength beam. The one exception is if you're using a diffraction grating, or prism of some kind, assuming it's transparent in both wavelengths and will cause them to diverge.

If it's collimated AND aligned, then the visible beam provides warning.

If it's out of focus or not collimated, then the density/intensity beyond point blank will be low.

I'd think what's really dangerous is collimated and off-axis.

 

[grainde]

Which is the/a common wavelength that is absolutely invisible to the human eye. Would love a 5W ver for some wood litho, but I don't want to pull apart any 532's I no longer have.

Sorry, but your question is odd.

1) Most wavelengths in the Electromagnetic spectrum are invisible to the human eye. We only see a tiny proportion of it.
2) Not sure why you would want to have an invisible wavelength to engrave wood?
3) You dont have a 532, by your own admission, so the point is mute?

The two IR wavelengths are 808 and 1064.

It would seem to me that if the IR is aligned with the visible 532nm or other DPSS frequency, then that's actually safer, since you've got your normal visual aversion to look away or blink.

I always figured if the passthrough IR was a safety problem, it would be either if/when there's still significant IR output that's not eye-safe, but is below the threshold for the DPSS crystals to convert and re-lase, or if said IR was well collimated, but off axis from the main visible light wavelength beam. The one exception is if you're using a diffraction grating, or prism of some kind, assuming it's transparent in both wavelengths and will cause them to diverge.

If it's collimated AND aligned, then the visible beam provides warning.

If it's out of focus or not collimated, then the density/intensity beyond point blank will be low.

I'd think what's really dangerous is collimated and off-axis.

Yes, but there is another situation we should consider; what happens when someone is eg burning, taking photos in front of the laser, using prisms / optics etc, but using saftey goggles that dont block IR only 532. If they get a specular reflection from a molten, or otherwise reflective surface, they can still get a direct hit from the IR.

I do agree though, the green will cause the blink reflex even with googles, due to the bright flash and yes off axis would be worse. :beer:

 

[Cyparagon]

The comparison is accurate enough and the point of the exercise, in case you forgot, was to show that the IR is collimated

Yes, it can be. But to have divergence close to that of the green is the exception, not the rule.

From a safety standpoint, a tighter IR is arguably more dangerous. But If you don't point the laser near your face, there's really nothing to worry about.

 

[grainde]

Yes, it can be. But to have divergence close to that of the green is the exception, not the rule.

From a safety standpoint, a tighter IR is arguably more dangerous. But If you don't point the laser near your face, there's really nothing to worry about.

Both the lasers I tested (only unfiltered DPSS's I have - ebay pen and 301 laser) and the 473 laser from KapHn8d all had a collimated output, thats 3 out of 3, so Im inclined to believe the opposite. It would be great to see more testing and maybe you have an example to the contrary or perhaps others could show some evidence to prove that these are the exception? :thinking:

I mentioned earlier:

Yes, but there is another situation we should consider; what happens when someone is eg burning, taking photos in front of the laser, using prisms / optics etc, but using saftey goggles that dont block IR only 532. If they get a specular reflection from a molten, or otherwise reflective surface, they can still get a direct hit from the IR.

I do agree though, the green will cause the blink reflex even with googles, due to the bright flash and yes off axis would be worse.

There are many examples where one should be concerned and careful.

Anyway even if, only some DPSS lasers have a collimated output, it would be wise to be cautious especially if the output profile of a laser is unknown. :beer:

 

[Cyparagon]

...thats 3 out of 3

Which is why I'm skeptical of the photoshop approach. The pictures I've seen (and taken) in the past all have larger IR spots than green.

Here's all I have to work with. One unfiltered green, one <$30 unfiltered camera, and a 760nm IR-pass filter:

It's really hard to tell where the green is in that one. I'll try to get a better video later if I can find one of my IR filters.

edit: found one. I don't know the specs, but it was out of a halogen slide projector. The same laser with an IR-stop filter:

edit: forgot to mention this is a fixed focus pointer. Video was taken at something like 15 feet.

 

[grainde]

Ok interesting and look forward to the video. I assume you had the focus set on infinity?

Would be good to see other results too, so if anyone else has tried getting a pic of their IR output please post the results here! :beer:

Edit: One thought it is possible that you have blooming in the videos you showed and that the pic was over exposed. When you reduced the intensity of the light (532 + IR) by adding a filter to show only the green, the dot was clearer and better defined. As you know camera sensors are especially sensitive to IR and this could give a much larger and over exposed dot? Cheers for the info.:beer: