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Question about laser mw ratings

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donaldduck

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Hello, this is my second post on the forum. I searched google for 8 hours trying to find a specific answer to this question.

I want to know about line lasers and their mw ratings. How are they measured since the beam is spread out and not concentrated on a spot like typical laser pointers?

Does the 5 mw rating on a class IIIa line laser mean it is 5 mw for the entire laser line if the beam was focused down to one spot?
 





mortuus

mortuus

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not sure what you mean spread out? if you point at something you will get a spot bigger or small depends on the wavelength of the laser. Yes if you point a laser and it reads 5mw then thats what the lasers power is, 5mw.
 
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donaldduck

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The laser line covers more surface area than a laser pointer concentrating all of its energy on one pinpoint spot. Does this mean a laser line is less damaging than a laser pointer of equal power?

To put the question into context, which would be more likely to cause eye damage. A 5mW 650nm laser line or 5mW 650nm laser pointer?

5mW laser line
images


5mW laser pointer
29062d1283067336-safety-question-about-5mw-red-laser-eyes-itching-img_0858.jpg
 
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Livinloud

Livinloud

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All a line laser is, is a optical lens in front of a normal laser. The lens has a groove in it that "spreads" the dot into a line. Hence they should be measured without the lens BUT there is about 2% of the lasers from China that are actually metered and honest readings are given. Most "5mW" are a lie
 
ultimatekaiser

ultimatekaiser

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It's supposed to be based on total emission at the aperture-all inclusive of ALL the light coming out. So 5mW for the whole line.
 
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donaldduck

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ultimatekaiser said:
It's supposed to be based on total emission at the aperture-all inclusive of ALL the light coming out. So 5mW for the whole line.
Click to expand...

Is aperture referring to where the beam is emitted from the laser or is it referring to the aperture of the eye (pupil)?
 
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ultimatekaiser

ultimatekaiser

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It's the total leaving the casing, that is humanly accessible during normal operation.
 
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donaldduck

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Thanks for the replies! It's making more sense to me now.

Just to be sure I understand this in the simplest of terms. In the pic below, if he turned around and got hit in the eye by part of the laser line, would it be much less severe than being hit by a laser pointer dot of equal mW? How do you calculate the amount of mW reaching his eye?

cross-line-laser-levels-111921-3650527.jpg
 
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ultimatekaiser

ultimatekaiser

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Correct. There are a lot of factors in calculating eye damage, but in this case it's considered eye safe for brief exposure.

It'd be the total power devised by the entire line length. Basically the diameter of all of the output.

For example let's say the line is 5 cm long, and in this example that you're using a 5mW laser. It'd be a power density if 1mW/cm^2 or in this case, just per cm since it's a line. Or 0.1mW per mm, and so on.

Hazard to the eye would vary a lot, based on ambient lighting (diameter of the pupil) and other things. But as a general rule of thumb, this would be generally considered eye safe. Provided you aren't staring into it continually and it's just a brief exposure. It'd still be crazy bright to look into. Not that I'd ever condone intra-beam viewing.
 
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Shakenawake

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5mW is pretty dim for red, to spread it out that much I question if the line would be that bright, so I am willing to bet the source is over 5mW, but that spread out, hmmm.

I think we are dealing with square cm here Ultimatekaiser, not cubed cm


probably the only way to know for sure, 100%, is to take the line part off of the source laser, LPM it, then divide this known power level by the length of the line, just remember, the length of the line on the wall is not the same as the length of the line at any point between the wall and laser, it will be shorter the closer to the unit you get, and thus more energy dense
 
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Shakenawake

Shakenawake

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yeah, just had to give you some crap, U.K.

I would guess this is a picture meant to showcase the laser, ie, an advertisement. the guy looks dressed for a date, not contracting work.
 
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