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How can i determine the power of a greel laser pointer without expensive equipment?

Radovsky

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I just bought a Chineese green laser pointer, it cost about 8 bucks. It has 3 labels: one thet says >5000 mW (obviously fake), one that says <5mW, and one that says <1mW. It's clearly more than 1 mW and i think it's moe than 5 mW but then how powerful is it? How can I find out whitout buying specialised tools?
 



smallfreak

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You can't. It does not cost you a fortune, but compared to your new posession everything is expensive.

These instruments are not rocket science (other than the Laser itself). It boils down to absorb the entire light (i.e the surface has to be mighty black) and to transform this energy into heat or electricity (for really low power and defined wavelength) that can be measured. There are DIY recipes here how to build a Laser Power Meter (LPM). But in the end, you will still have to calibrate them against a known sample or you can throw dices again.

I throw my dice and it says:
Your Laser is between 50 and 70mW.
Wild guess, but many of the "cheap Chinese <5mW class IIIb burning torches" Lasers fall within this range. It is unlikely to be lower than 30mW and similarly unlikely it will exceed 100mW.

You can do a quick test. Paint a match black and point at it with the Laser. If it lights quickly, you are certainly in the >1W range (highly unlikely). If you can focus the beam and even then the match won't light, no matter how long you try, then you are certainly below 10mW.

Would you need more precise numbers? Would that change anything? Keep the ray (even reflected) off your eyes and the eyes of every other living creature and everything should be fine.

If you get the impression that it is "damned bright" and you can't easily look at the spot on a light surface - get a pair of proper Laser Safety Goggles soon. Chances are, that the beam IS dangerous to the eye and you have just two of them.
 

paul1598419

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Those 301 or 303 pointers all end up somewhere between 50 mW and 90 mW, but most of mine run very close to 80 mW. The only way you can know for certain is to measure the power with a calibrated laser power meter. I have four of these and would gladly measure it for you, but the cost of shipping it both ways would be more than you paid for it.
 

Nexgen

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Everything that lights a match with focused beam is >50mw

“My experience”

I own many pens that are measured with my LPM and none of them being 30-40mw lights a match with loupe.
 
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paul1598419

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You got your sign wrong, Nexgen. I think you meat to say >50 mW. It's okay as I know what you meant to say, but others may not.
 

Nexgen

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You got your sign wrong, Nexgen. I think you meat to say >50 mW. It's okay as I know what you meant to say, but others may not.
My bad, corrected.
To burn matches without focusing, you will need at least 180-250mw
 

brendon7358

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Where do you live? If you live in the US you can send it to me and I will test it for free. You just have to pay shipping ($3-5 each way). If you don't trust me I'm sure many other members would be willing to do the same. Personally I think it is very important to know the true power of your laser.

It would be difficult to test the power just by seeing if it can burn something due to the following. Based on the fact that you bought the laser for $8 I assume you don't have laser safety goggles, and therefore it would be very dangerous to try and point it at something (especially something reflective) right in front of your face to see if it burns or not.

It would be much safer to just assume it's >100mW and take the proper safety precautions. Alternatively you can get safety goggles (I sell some fairly cheap), or have someone test it for you. They could also check the IR which is another hazard you should be aware of with 532nm lasers.
 
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hakzaw1

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From Brendon "Where do you live? If you live in the US you can send it to me and I will test it for free. You just have to pay shipping ($3-5 each way). If you don't trust me I'm sure many other members would be willing to do the same. Personally I think it is very important to know the true power of your laser. "


^^ that fits with my suggestions.. please go to the welcome section where we have many 'sticky' posts-- give those a look--they will help you a lot here.
ALSO you will see many fine posts from brand new (and sometimes even old) something like this "Hello from Tenn.' This is not only proper and shows respect .. it can be a 'game-changer'...... ?how?
IF you had finished your profile and placed a nice 'intro' a bit about you--where you are ATM... you might already know the mW of your green pen-pointer --- HOW?
The WELCOME section is seen by a lot of members....and gets a lot of 'greets' to the new members...and one of those very well could be a member with a meter.
And by putting your location in your thread title AND in your profile--IF WANTED-- you could meet other members and it a great time when you can 'talk' laser to another person WHO UNDERSTANDS and will not be asking you____ Why Lasers? Why do you have so many? What are they good for??-- being new that may not be happening (YET) HOWEVER I must tell you that lasers are highly addictive.. one or more will never be enough..symptoms include 'Empty Wallet/Low Bank Account Balance ' and staying up all night reading the laser forums. and moar.
This forum is addictive and all the various LEMs are highly addictive.. search 'SELEM Lasers' the YTube vids are OK, but nothing like seeing in person..
IF I knew where you are- I would have told you about the next LEM near you.....
hope to see you at SELEM 13 ( in N.C. mid august)
BTW
I drive 17 hours each way (4 times ) to attend SELEM. ( & flew one time-hated it!).
 

defy

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Those 301 or 303 pointers all end up somewhere between 50 mW and 90 mW, but most of mine run very close to 80 mW. The only way you can know for certain is to measure the power with a calibrated laser power meter. I have four of these and would gladly measure it for you, but the cost of shipping it both ways would be more than you paid for it.
somewhere i read that thoe ebay 301/303 lasers are fake/rubbish quality. so they are actually good? shld i get one of those?
 

GSS

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For $8 they are great, and it's usually best to get 2 or more because pretty much %50 of the time one will be alot stronger than the other. The rubbish name comes from them being mass produced very quick and cheaply.
They are great starter laser's and like everyone said they will do from 40mw to 80mw+ They are actually a nice host for the money, and can focus. They are hard to mod and work on as there's tons of glue inside, but again for the money they have the potential to last.
They are also the laser that starts you into needing saftey glasses even more. You can get complete kits with cheap glasses and cheap charger for around $15.
 

paul1598419

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Yes, you can get a crapfire 18650 battery, and cheap charger and cheap safety goggles with a 303 laser for ~$15.00 for all of it. Often the goggles are enough to protect you from an accidental laser strike to your eyes, but wouldn't be adequate for 1 watt or higher power lasers. For the money, it is better than nothing at all and can be a good way to get acquainted with rechargeable batteries and safety eyewear.
 

hakzaw1

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^^^ great advice from Paul.. I bought the cheapest when I started.. later bought better, then much better (EAGLES) my old googles are now 'guest' eyewear.
 

defy

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Yes, you can get a crapfire 18650 battery, and cheap charger and cheap safety goggles with a 303 laser for ~$15.00 for all of it. Often the goggles are enough to protect you from an accidental laser strike to your eyes, but wouldn't be adequate for 1 watt or higher power lasers. For the money, it is better than nothing at all and can be a good way to get acquainted with rechargeable batteries and safety eyewear.
are rechargable lasers any good, cos id rather have something easily replaceable in terms of battery/charge
 

Immo1282

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are rechargable lasers any good, cos id rather have something easily replaceable in terms of battery/charge
The batteries in cheap lasers are always removable. They tend to use 18650 or similar rechargeable 3.7v lithium-ion cells, like the ones used in high-powered torches and vape units. You will need a charger to use these, but the cheap offerings often come with this too.

Easily replaceable is easy - just buy a few batteries of the same size, charge them all up and swap the battery when it runs out.
 

defy

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The batteries in cheap lasers are always removable. They tend to use 18650 or similar rechargeable 3.7v lithium-ion cells, like the ones used in high-powered torches and vape units. You will need a charger to use these, but the cheap offerings often come with this too.

Easily replaceable is easy - just buy a few batteries of the same size, charge them all up and swap the battery when it runs out.
and the lasers themselves are good? powerful? good qualityish?
 

GSS

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and the lasers themselves are good? powerful? good qualityish?
Again for even as low as $6 minus the glasses and battery yes they are good and powerful enough to blind you..
You might even be surprised how nice a 301 host is for $6 to $8 or $12 to $15 for a kit. It even has a nice focus knob and even there are some 301's with the option of having a star pattern add on cap..
If you are talking about rechargeable laser's with a built in battery, "I" have yet to see one that lasts. Plus if there is an issue with the battery you might not be able to take it out without possibly destroying the host. So it's just better in my opinion to be able to swap battery's.
If you see a rechargeable built in battery laser for $5 than try it as it's only $5...
 




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