Do I need laser goggles for this?

Laser
#1

I’m planning to do some laser / fiber optic tests. As a newbie to this sort of stuff, would I need protective eyewear if I’m using one of these up close? I imagine I do, but what type/kind of protective eyewear would you recommend?

Pinty Hunting Rifle Green Laser Sight Dot Scope < 5mw Adjustable with Mounts https://www.amazon.com/dp/B019Q05CNY/ref=cm_sw_r_cp_apa_i_NoF2CbQF5KWWJ
Team Electronics, do we have any instruments to measure the loss in fiber optic cables and connections?

@Team_Electronics @Team_Hatchers

Thanks in advance!

#2

If you were only going to use it for shooting protective eye isn’t really required, the output isn’t likely to cause eye damage in normal use. It sounds like you aren’t planning on using it for that though. In that case it would probably be a good idea for your eye comfort.

I don’t have much experience with eye protection with lasers so this advice is worth what you have paid for it. The output is visible light so I would expect sun glasses would be useful. If the lenses are very dark you will not be able to see much with the laser off. Most protective eye wear is intended for non visible light and the glass can be made to block the laser light without blocking much light in the visible spectrum. I have not heard of glass that will block a narrow part of visible light. If there is such glass I would expect it to be very expensive.

As Captain Obvious might say, “you might just be careful to not point it at your eyes” :grinning:

Russell Ward

#3

You want something that blocks 532 and 1064nm light - rule of thumb, if it doesn’t have an OD rating at the specific wavelengths printed on the lens, it’s junk. These seem suitably specced and moderately trustworthy: https://www.amazon.com/dp/B00UJBGUMM/

However, for a laser this weak, I personally wouldn’t worry about it, just don’t stare into the barrel.

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#4

I worked on the earliest laser printers that were loaded with shiny surfaces and mirrors. If this phrase gives you pause… USE EYE protection. " Avoid Staring at Laser with Remaining Good Eye".

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#5

It’s a Class IIIa laser, so therefore, IAW CFR Title 21, section 1040 - it is not eyesafe. If it were eyesafe it would be certified as a Class I laser.

Lasers are typically classified at the system level, i.e., with all the various covers and interlocks in place. If you plan to remove any of those items, the laser itself might be a higher class.

You should be looking for “laser attenuation” glasses or goggles specific to 532nm - especially if you plan to operate it with the covers removed. I’m going to speculate that if we have anything it’s likely to be suitable for 633nm.

That said, be advised that with laser attenuation glasses/goggles it may be difficult to actually see enough of your laser beam to perform your tests - hence the comment from @steve_a about the remaining good eye.

Many years ago while designing/building/certifying a laser system I read an article in (SPIE) Photonics Spectra magazine - written by a senior laser researcher describing the laser eye injury that he personally suffered. It’s not in the least little bit like a sunburn. It was the most horrifying and gruesome thing I’ve ever read.

Long term or high power laser exposure can also induce cataracts. I do not know at which wavelengths this is relevant.

There’s some reason it isn’t a Class I laser. Eyesight is precious. Protect yourself.

#6

Sure, but this is basically a laser pointer (also generally class 3a). And the barcode scanners at the supermarket are not class 1 either (class 2). You’re not going to accidentally blind yourself easily with this.

From wikipedia:

Lasers in this class are mostly dangerous in combination with optical instruments which change the beam diameter or power density, though even without optical instrument enhancement direct contact with the eye for over two minutes may cause serious damage to the retina. Output power does not exceed 5 mW. Beam power density may not exceed 2.5 mW/cm2 if the device is not labeled with a “caution” warning label, otherwise a “danger” warning label is required. Many laser sights for firearms and laser pointers commonly used for presentations are in this category.

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#7

Anything over a class 1 laser is a concern. I used to gripe at safety glasses around metal work. Age has taught me a lot. Is it worth the risk for bravado or inconvenience? This is one category when the excuse of being called a “Whimp” is worth it… you only have two eyes and neither is a spare. Let me know when you can prove otherwise.

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#9

David,
It looks like this is a free beam laser (not fiber optic coupled). If you are planning to go into fiber optics as implied by your first line, I would start out with a laser diode that is pre-coupled. Almost all of your loss is in the coupling, not the fiber optic cable itself. In glass fiber optics, loss is often quoted per kilometer. The alignment of a diode and fiber is challenging and ranges from 50-85% efficient when done commercially. You will need to work hard to match this efficiency without the advantages of a specialized shop.

Eye safety is discussed extensively in the ANSI Z136 standard (you probably want Z136.1). The key is power density (mW/cm^2 or mJ/cm^2). This beam is collimated (more dangerous as it does not spread out) and ‘continuous wave’ (not pulsed, safer as you don’t need to worry about peak power, only average). Echoing what John Marlow stated above, laser class is determined by the entire packaged product, NOT what you can get at with a screwdriver, etc. If it’s a Class 4 inside a locked box and attenuated so that the output is Class 1, it can be sold as a Class 1. You are opening the box and caution is justified.

Note that laser light coming out of a fiber optic is not collimated. The numerical aperture of the fiber (NA, in air, sine of half angle of light emission) determines how the light spreads out. The further away from the fiber tip you are, the lower the power density (more area, same amount of optical power). In the Class 3b devices I use with 0.22 NA fibers, the power density drops down to eye safe levels in a short distance (for my wavelength/power/NA combination, 10-15 cm. NOT a rule of thumb).

Side note: although this is a 532nm laser, there may be other wavelengths present as alluded to above. There was an article a few years ago (Physics Today?) describing an experiment for high school kids with 532nm laser pointers and a CD as a grating. These lasers are often frequency doubled 1064 nm (not visible). The 1064 pump is much more powerful than the visible output. In inexpensive lasers, the pump beam was found to be frequently not filtered out of the output. As long as these are co-linear, the eye risk is partially mitigated by the blink response of the eye (to the green light). As soon as the light goes through a lens/prism/etc, the 1064 and 532 nm are no longer aligned. I unfortunately don’t have the reference for this handy.

If you want to discuss the overall design, I might be able to give you some suggestions on the light source to reduce the potential safety concerns. For example, in low power applications, even though the coupling efficiency into fiber optics is poor, LEDs may make more sense.

r/
David

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#10

Currently the ELab does not have any laser or fiber optic related test gear.
Might check w/ @Team_Science

#11

Thank you @drbusch, @John_Marlow, and everyone for the information. I purchased the glasses mentioned by @halachal; they were more expensive than others, but I now understand why, thanks everyone!

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#12

Good for you! Hope your project succeeds!

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#13

Thsnk you @steve_a!