Question on Focusing a Laser

Even with the safety glasses that came with the laser I have, I feel I can’t really tell if the laser is focused to the finest point? To me there is still a kind of flare effect keeping from seeing it as it really is.

Question: Can Solar Eclipse glasses be used safely for this? Will it even work?
I’m asking before I try it.

Best to just examine the width/quality of the line with a magnifier after burning a focus ramp test (diode laser).
I had success with testing on a piece of masonite. I could see a zone of a few inches up the ramp where things looked good. Next I centered that area and reduced power to just enough to mark the masonite. This left a very short line (about 1/2") where I could even see any hint of a line. This became my focus sweet spot (about 3mm higher up than the built in “kickstand” focus setting mechanism).


Rather than risk your one and only set of eyes, use a ramp test instead.

Draw a long skinny line in light burn. Put in a piece of material. Block one end up off of the waste board. Focus the laser at your estimated prime setting. Run the test graphic on the slanted wood. Observe the quality of the line, then note where the laser head was when you got the best, sharpest, smallest line. That will be where you measure the focus distance.

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Answer: no.

More than you probably want to know:

The money quote:

The maximum transmittance of 0.0032% corresponds to an optical density of 4.5, which is inadequate for a laser source at arm’s length.

Good-quality laser glasses will have an optical density as much above 6 as you can afford, with finicky calculations depending on the actual laser power that may justify a lower OD in some situations we probably can’t evaluate.

Aaaaand then there’s the whole question of whether the eclipse goggles actually meet any particular specifications.

Bottom line: do a ramp test and avoid the direct observation risk.

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Thank you all!

This is very controversial subject…

This is Russ Sadler video on beam safety is worth a watch, at least it’s an opinion from an engineer, not optical, but mechanical. Nevertheless a good video, even having to put up with his Brit humor.

I’ve tried the safety sheets and, even though I did photography, the terminology itself always has me questioning…

This has no meaning to me in this context… probably why I didn’t do well at this level of optics.

It seems to imply you hold any source of laser and arms length and look down the beam (with your remaining eye) as it’s lasing…

I think what comes with the machine is probably adequate.

Millions or 100’s of millions of these are sold to pretty ignorant people and I have never heard of someone blinded by one. Same with someone getting across the lps hv a co2 and ended up dead… Doesn’t mean it hasn’t happened, but it’s not enough to even make it on the Internet… the blinding lasers there are the hand held ones they tend to point at aircraft and I’ve not heard of it being permanent.

When researching for my fiber 1064nM sources, I found virtually the same source that’s in my MOPA, without any of the adjustments, used to clean rust off of steel… The video was a group of people using 100+W machines, cleaning metal with hand held emitters and no safety glasses on any of them.

I’ve marked hot dogs with the co2, but nothing biological seems to really be affected by this frequency. Of course I have lots of setting, but if it won’t mark a piece of baloney…?

What isn’t spoken about, that users of lasers know all too well is the bright emission from the actual lasers work, which isn’t the lasers frequency. Most materials at some point are being vaporized and these reactions create a wide range of frequencies, wider then my safety glasses can protect me from or I wouldn’t feel like it’s too bright…

No matter how well it protects, excluding total darkness hood, it’s likely doing some type of long term damage to your eyes…

I try to put it this way…

Don’t depend on technology with your life/eyes/limbs/feet/hands/fingers/toes and any other body part you’d like to keep, on the machines safeties, including eye protection.

Engage your brain before lasing - Safety is between your ears

Set things up so you don’t have to look at these areas for any longer than necessary to get the right adjustments.

Besides the fact that some people are mesmerized by these (like me), so only look when needed.


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My job checklist. :smiley: :smiley:job_checklist

It’s all about power density on your retina.

A moderate laser source a meter away beats the sun, hands down, for intensity when it’s whoops focused through your eye’s lens onto your retina.

A diode laser is maybe 10 W in a 10 mm square-ish patch at arm’s length, which works out to 100 kW/m². Compare that to the sun at about 1 kW/m² on a clear day: both sources fill your pupil, but the laser dumps a factor of 100 more energy into your eye.

Which is why you need an OD of 6 for lasers, rather than 4 for the sun, to cut the power down to something plausible.

He’s a good egg, but my life is too short for all his long-format videos. I prefer a written document I can absorb at 10× that speed and refer back to without re-watching.

There is a significant difference between skin / flesh damage and retinal damage. From what I’ve learned, the latter produces a distinct pop in your head and then you never read another word in your life. Sort of instantaneous 100% macular degeneration.

You probably stop making blog posts right after that, too …