Eyewear for DX 200mw red laser...?

[ks_physicist]

I am researching what appropriate eye protection to purchase for use with higher powered red lasers.

I found a nice guide (http://www.stockeryale.com/i/lasers/lit/selecting_laser_safety_eyewear.pdf) that gives a method for calculating a safe OD. If I assume a 50% margin of error, that 200 mw laser "could" be up to 300 mw, and using the formula I find there I should look for a set of goggles that can handle the laser wavelength with an OD of 3.

The affordable glasses I had been looking at were at MWK (http://www.mwklasers.com/goggles.htm), but their OD is only 1.8. Using the formula from the previously mentioned site, that would result in a residual 4.8 mW in the event that a 300 mW beam directly hit the glasses.

Not bad, but not up to the margin of safety suggested by the Stockeryale site. Looking at the sources mentioned in the stickeyed thread finds most glasses of any OD running in the hundred to several hundreds range.

I'm a teacher, so I'm not running on a huge budget, and I was hoping to find decent, safe eyewear for a modest price. Are there any other options out there, or am I going to be stuck paying a couple of hundred USD for acceptable safety?

 

[pyrokid3]

I have heard good things about wicked shades, but I have no first hand experience with them. I have no idea how to read their graph, but it looks like it has a OD of 5 for only $50 plus shipping.

http://www.wickedlasers.com/lasers/Red_650nm_Sport_Elite_Goggles-18-16.html

 

[ks_physicist]

Yeah, I emailed them to ask about the other red-protecting glasses they have. I'm not sure the shades (linked above) have good enough protection around the perimeter.

Frankly, I'd rather have welding-goggle or opaque laboratory-goggle type frames with laser protective lenses. No chance of a side-shot with those. Still, if they can give me the OD (or preferably the absorption/transmission graph) for the LaserShades, they might be acceptable.

 

[Timelord]

The shades linked above are more than enough for what you are looking for. IMO they blocked out too much red 100% so if you are doing experiments you won't see anything. Your best bet is get the lasershades instead HERE>> http://www.wickedlasers.com/lasers/Red_650nm_LaserShades-49-16.html

These give adequate protection and you can still see the dot from the laser to do experiments. I know as I have all the wicked lasers goggle and novalasers ones too. So save yourself $10 and go for the lasershades

 

[Hans Dorn]

Correct me if I'm wrong, but aren't 5mW lasers safe to use without goggles?

(If don't do something stupid like looking directly into the beam)


Going from there I'd think that OD2 (1/100) should be fine. It effectively turns your 200mW laser into 2mW.


Regards Hans

 

[RDZombie]

Correct me if I'm wrong, but aren't 5mW lasers safe to use without goggles?

yup

 

[eyeeatingfish]

Im new to the laser world and some of the DX lasers seem cool but i dont know much. 200mw ot 50mw are power ratings right? Then there is red and green lasers and apparently we need safety goggles? Is this because they are so bright or some radiation?

 

[bleufan]

200mw and 50mw are indeed power rating of the power of the light output. Above 5mw I'd recommend safety glasses, also because that's the line in the regulations. Without those safety glasses, a direct or specular reflected beam would create a blind spot on your retina in your eye. Depending on the power this could be before you have your eyes closed or practically instant.

So, at the power levels of 50mw ~ 200mw, also get decent safety glasses. Note that safety glasses work only for specific wavelength of laserlight. Red lasers need different glasses than green or blue.

Also, cheap green lasers also emit infrared laser light. This is invisible or only visible at dangerous levels. The average safety glasses won't protect against this.
This infared is because of the way green lasers work. Decent lasers have IR filters to keep this out, really cheap ones do not have this safety.

Note that these power levels might be including the emitted or even blocked IR light in case of a green laser. This way, you have a fraction on the power in the visible green, but the most part in invisible dangerous IR light.

So be carefull, but once you have a decent laser, it's so cool! Even a true 5mw green laser (with IR filter) can give you more than enough pleasure to start with.

 

[eyeeatingfish]

200mw and 50mw are indeed power rating of the power of the light output. Above 5mw I'd recommend safety glasses, also because that's the line in the regulations. Without those safety glasses, a direct or specular reflected beam would create a blind spot on your retina in your eye. Depending on the power this could be before you have your eyes closed or practically instant.

So, at the power levels of 50mw ~ 200mw, also get decent safety glasses. Note that safety glasses work only for specific wavelength of laserlight. Red lasers need different glasses than green or blue.

Also, cheap green lasers also emit infrared laser light. This is invisible or only visible at dangerous levels. The average safety glasses won't protect against this.
This infared is because of the way green lasers work. Decent lasers have IR filters to keep this out, really cheap ones do not have this safety.

Note that these power levels might be including the emitted or even blocked IR light in case of a green laser. This way, you have a fraction on the power in the visible green, but the most part in invisible dangerous IR light.

So be carefull, but once you have a decent laser, it's so cool! Even a true 5mw green laser (with IR filter) can give you more than enough pleasure to start with.

To tell the truth, im not even sure what I would do with a laser if I got one...

What are the uses besides popping ballons?

 

[2xTrinity]

To tell the truth, im not even sure what I would do with a laser if I got one...

What are the uses besides popping ballons?

Green lasers, even <5mW green lasers, can be used to point at stars. The reason green works but red does not is both because our eyes are about 4x more sensitive to green for a given mW output, and, green gets scattered a lot more in the atmosphere, making the beams are visible. In adition to pointing at stars, low-power green lasers can also be used to point at other things, like projector screens and chalkboards :thumbsup:

If you were wondering about responsible uses for handheld lasers >5mW, there aren't very many...

but here is one that I did recently -- I used a 30mW green laser, with a big plastic diffuser around it, to create a speckle pattern (coherent noise) that is visible in the shade outdoors, as part of an optics demonstration -- the direction the speckle appears to move when the observer moves their head indicates whether they are nearsighted or farsighted. I did this because there were no outlets to plug in actual lab lasers. The laser was actually fastened to a display board, and completely diffused.

IMO "waving around" a high power (>5mW) laser of any kind is almost always a bad idea. High power lasers are best kept to optical benches, with appopriate eyewear among all nearby.



FYI the reason 5mW was chosen as a limit is that it's actually a threshold above which the heating by the laser causes retinal damage faster than the blink reflex can compensate.