How to tell mW

FrodoBaggins · May 25, 2013

Hey Guys,

I recently purchased a green 100mW laser, but I'm not sure that it is actually 100 mW (The seller sold it to me with no sticker, which is highly suspicious) - I want to know if there are any tests I can do to prove what mW it is.

I have tried

Cutting black electrical tape
Lighting a match

It could not accomplish either task, but the reflected dot is still pretty bright, and leaves me with an afterimage for a couple of seconds.

Any advice?

-Frodo.

Cyparagon · May 25, 2013

Use your laser power meter. Don't have one? See the following thread.

Thread: What if I don't have a laser power meter.

hwang21 · May 25, 2013

Dang, beat me to it. You could try burning tests as rough estimation, but it's not very accurate due to focusing, light absorption, etc. Watch the video styropyro made, it's very good at addressing general power abilities. I would say your laser could range from 5mW to 50mW, no real way to saying though. Did you try coloring the match tip black? Focusing the laser onto the blackened match tip or onto the electrical tape?

EDIT: Also, watch out for leaking IR that you can't see. Even if the green laser light doesn't enter your eye, if the IR laser light does it can still damage your eyes.

Livinloud · May 25, 2013

burning tests dont work for rough estimations. a poorly focused 1W 445nm wont burn but yet a focused 100mW 532nm will burn. ONLY way to tell power is with a LPM, plain and simple, no argument needed

hwang21 · May 25, 2013

True. However, if all the lasers are focused... it can't be terribly difficult

norbyx · May 25, 2013

Yeah a LPM is a tool that every fan of lasers should have.
There is a stickie that has a list of all users with LPM all arround the world. Maybe someone is near you and you can ask him to check your laser, usually is done for free...

hwang21 · May 25, 2013

One day, when a LPM costs as much/less than a laser...

daguin · May 25, 2013

hwang21 said:
One day, when a LPM costs as much/less than a laser...

:crackup: In the mean time hobbyists and sellers will keep fooling themselves to rationalize why they don't need an LPM :crackup:

Peace,
dave

Lazerbeak · May 25, 2013

FrodoBaggins said:
...the reflected dot is still pretty bright, and leaves me with an afterimage for a couple of seconds.

Any advice?

-Frodo.

~ LB

FrodoBaggins · May 25, 2013

Lazerbeak said:
~ LB

Thanks for the replies guys, I think what I will do is look for someone with a LPM that I know, if I can't find anyone, I'll just send it off to one of the members of this forum in that thread.

With regard to glasses, I'm in the process of looking for and buying some. They're quite expensive, but you can't put a price on vision. Can someone make a recommendation for some good glasses for me? I'm only using green lasers - But there are just so many choices, and I'm a bit overwhelmed with all of them

Lazerbeak · May 25, 2013

I got a pair from here...
Safety
around $40 and a forum member. I actually need to pick up a pair for green myself

These are pricey but I hear are very good, I wouldn't mind having a pair...
Thorlabs - Certified Laser Safety Glasses

In my Sig is some good info. Sigurthr's post describes how to make a beam shroud so you can enjoy high powered beams without glasses, which can be nice

They're easy to make and it's nice to just enjoy the beam sometimes.

I'm a big noob too, so don't be put off, just enjoy yourself safely

~ LB

grainde · May 25, 2013

Lazerbeak said:
I got a pair from here...
Safety
I actually need to pick up a pair for green myself

Which ones did you buy? If they were for 445's and up to 540 nm they will protect from 532. If you want to check, look up the abs vs wavelength graphs on the eagle pair website...

:beer:

Lazerbeak · May 25, 2013

grainde said:
Which ones did you buy? If they were for 445's and up to 540 nm they will protect from 532. If you want to check look up the abs vs wavelength graphs on the eagle pair website... :beer:

Derp, Thanks Grainde! That's awesome, I didn't even think about that at the time I was only buying for blue and red at the time. I'm getting a 520nm that'll work out perfect. :beer:

~ LB

Pi R Squared · May 25, 2013

Hello Frodo, what country are you in? It will make a difference how people advise you. If you can afford some medium priced glasses then take LazerBeaks advice and buy from here: Safety
If you need something cheap I can recommend these: HDE® Laser Eye Protection Safety Glasses Goggles for Green Blue Lasers W/ Free Hard Case - Amazon.com
Remember some 532nm lasers are IR filtered and some are not.

Alan

scumbagatheist · May 25, 2013

Hello Frodo. The link of members with LPMs can be found in my sig. Good luck, and eye safety and all that.

Livinloud · May 25, 2013

Pi R Squared said:
Hello Frodo, what country are you in? It will make a difference how people advise you. If you can afford some medium priced glasses then take LazerBeaks advice and buy from here: Safety
If you need something cheap I can recommend these: HDE® Laser Eye Protection Safety Glasses Goggles for Green Blue Lasers W/ Free Hard Case - Amazon.com
Remember some 532nm lasers are IR filtered and some are not.

Alan

I would never recomend that second pair! The first pair at survival laser are great but the second pair are junk. If you want a cheap pair then go to the yellow link in my signature and look under safety. The uvex pair are much better than those but they still dont protect for IR.

How to tell mW

FrodoBaggins

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FrodoBaggins

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