Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Laser Pointer Store

Green laser acting up...

Seldovia

New member
Joined
Nov 10, 2013
Messages
23
Likes
2
Points
0
Without a LPM you would most definately not know the power of it. My two $5 405nm ebay pens are doing 84mW and 95mW each. A $5 "toy" is doing almost 100mW and to the eye it looks weak as heck but that's due to the wavelength charateristics. Sorry but w/o a LPM you can't tell me what power they are doing because its physically impossible to know
You're right. Without an LPM I won't be able to find the power. But there is still an obvious difference between 10mw a 100mw.
 

Livinloud

New member
Joined
Feb 21, 2013
Messages
5,047
Likes
231
Points
0
Ok we are talking about a 405nm here. You do realize that's like 30nm away from UV........invisible! Its not supposed to be super bright. Its actually one of the dimmest laser per mW available. I'm sorry but you don't know what you are talking about and we are only trying to help you out. Ignorance is not going to solve anything.
 

Seldovia

New member
Joined
Nov 10, 2013
Messages
23
Likes
2
Points
0
Ok we are talking about a 405nm here. You do realize that's like 30nm away from UV........invisible! Its not supposed to be super bright. Its actually one of the dimmest laser per mW available. I'm sorry but you don't know what you are talking about and we are only trying to help you out. Ignorance is not going to solve anything.
I am the one who doesn't know what he's talking about? I'm the one with the laser in my hands. I'm not talking about brightness. If this was "100mw" l would feel something when it hit my skin. Just because your ebay laser was overpowered, doesn't mean everyone else who buys one is going to have a 100mw.





100mw you say? Interesting.
 
Last edited:

Livinloud

New member
Joined
Feb 21, 2013
Messages
5,047
Likes
231
Points
0
Well considering im not the only one who has experienced this; there is a thread on this site with hundreds of people who have experienced the same results. You can shine a 200mW laser on your skin and it doesnt mean you are going to "feel" something. Everyone skin reacts differently. I am sorry but you can ask anyone else, who knows what they are talking about, and they will tell you the same thing.

It is very obvious that you think you know what you are talking about. That is fine but when you are wrong, you are wrong. Happens to all of us. Its how you react to being wrong that separates everyone. If all you are going to do is push back on me and say im wrong then you will get no help what so ever. BTW a picture doesnt mean a single thing. No one has a special talent were they can be like "oh thats a 56mW 405nm laser"

405nm "cheap" lasers, EVEN IF LABELED AS 5mW, WILL 99% OF THE TIME BE 80-120mW. You do know the reason why they label them as 5mW right? Search ebay for "5mW laser" and you will get ~3,838 results. About 3,700 of those will be over 5mW and most likely 3,600 of them are 300% over spec or more
 

Livinloud

New member
Joined
Feb 21, 2013
Messages
5,047
Likes
231
Points
0
Thats not what im saying.......Im saying you cant say its a 10mW 405nm without metering it. I cant tell you its a 100mW 405nm without metering it myself. Thats why i gave you a ballpark of what other members have metered out of their cheap 405nm lasers; 80-120mW. METER IT OR YOU CANT CLAIM AN OUTPUT, simple rules that the forum runs on. Go check out other build threads and if the owner claims its xxx mW without a power graph or photo, i bet you there is a member who posted "how do you know the power of the lasers, did you meter it?"

All i was trying to prove is, you dont know the power so you cant claim it as something. Also you dont know the power so you dont know how dangerous it is.

Also something that hasnt been mentioned; your 532nm could have a crystal knocked out of place this causing low green output but there could be a ton of IR output. iirc it takes like a 1W 808nm diode to produce 300mW of 532nm. Could be off on that but thats whats ringing a bell in my head. So you have no idea how much IR is coming out of that laser. Most cheap 532nm lasers are 75% IR anyways. Thats how they hit the 100mW mark. My cheap 532nm pen did like 20mW of green and 40mW of IR. Another 532nm pen did 60mW of green and 5mW of IR. Both bought from the same seller but WAY different results
 
Joined
Aug 14, 2013
Messages
2,655
Likes
150
Points
0
It also depends on the laser, wavelength, and how fine the beam is. I have had >200mW 660nm diode
lasers in the past which would light matches, and could never feel anything. Now my 100mW argon is
another thing entirely. For one thing, there are 6 lines from 455-515nm, so shorter wavelengths and
more chances of an interaction. Then being a recently refurbed argon, of course the beam quality is
excellent. I can most definitely feel it when this laser hits my skin, and if left in one place it would
cause a very painful and probably very easily infected burn.

So perhaps now you may begin to see why the feel of a laser on the skin is in no way an indication of
its actual power.
 

NO4H99

New member
Joined
Sep 9, 2013
Messages
553
Likes
45
Points
0
Nah LivinLoud, the OP is right on this one.

The stinging fingers test is quite accurate, if you know how to do it.
Just shine the laser from precisely 14cm away onto the back of your RIGHT ring finger. Holding both your finger and the laser very still, time exactly how long it takes to feel heat. Then just multiply the number of seconds by 16.853 and add 7. Subtract the answer from 400 and the number you come up with will be the exact power in mw!

Just a disclaimer, you might want to do this 3 or 4 times and average the result (due to fluctuations in your body temperature). Also, this only work for lasers between 2 and 400mw.

Good Luck :beer:
 
Last edited:

Livinloud

New member
Joined
Feb 21, 2013
Messages
5,047
Likes
231
Points
0
Nah LivinLoud, the OP is right on this one.

The stinging fingers test is quite accurate, if you know how to do it.
Just shine the laser from precisely 14cm away onto the back of your RIGHT ring finger. Holding both your finger and the laser very still, time exactly how long it takes to feel heat. Then just multiply the number of seconds by 16.853 and add 7. Subtract the answer from 400 and the number you come up with will be the exact power in mw!

Just a disclaimer, you might want to do this 3 or 4 times and average the result (due to fluctuations in your body temperature). Also, this only work for lasers between 2 and 400mw.

Good Luck :beer:
:crackup: :shhh: I wont tell ;)
 
Joined
Nov 2, 2012
Messages
617
Likes
104
Points
0
You can gauge the relative power of lasers (don't do this with class IV lasers) by putting on your safety glasses, drying your lips, and aiming the laser at your lips. They are sensitive enough that I can feel a slight warmth from my Skylaser 520nm, which is probably very close to 50mW, as rated. The 405nm feels warmer than that, but not as warm as the Lazerer 450nm, which LPM'ed at 127mW when it was new.

Don't do this without putting on your safety glasses. I usually aim the laser at a slight downward angle to keep it away from my eyes.

I don't know what the exact output of the 405nm is but it's a probably safe bet to say more than 70mW, but less than 120mW. If I had thought it was a 10mW I probably wouldn't think so now.

Red and IR lasers won't be absorbed as much as <520nm so this test won't give accurate "readings" if comparing these lasers to green/blue/violet. Probably not accurate with an un-IR-filtered 532nm either. I wouldn't bother.

Bad idea to try this with class IV lasers since you'll probably just burn yourself. Also, excessive eye hazard even with glasses.

Again, never do this without wearing the wavelength-appropriate safety glasses. If anyone thinks this idea is bad because it involves aiming a laser at your face, I'm not going to disagree with you.
 




Top