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05-10-2012, 12:35 PM #1
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netiks
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Simple way to measure laser power

Simple way to measure laser power
If you have a multimeter with temperature function just drill a hole in the cpu aluminum radiatior and glue multimeter termocouple inside it ..after that you just need to calibrate it to show mw instead temperature with some resistor pot on termocouple

Last edited by netiks; 05-10-2012 at 12:43 PM.

05-10-2012, 02:08 PM #2
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Cyparagon
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Re: Simple way to measure laser power

Except... Y'know... the temperature rise isn't linear, but quadratic or maybe some higher-order polynomial. Good luck correcting that with a DMM.
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05-10-2012, 02:56 PM #3
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netiks
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Re: Simple way to measure laser power

Its simple You just need to know power temperature dissipation for particular cpu radiator. It will not be 100 percent correct because of room temperature is not always the same but this should work for some basic power measurement

Last edited by netiks; 05-10-2012 at 03:01 PM.

05-10-2012, 03:54 PM #4
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sinner
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Re: Simple way to measure laser power

With due respect, if that was the case lpf would have seen it way before 2007.

There is already a bunch of threads regarding DIY LPM's , IR Thermometer Based LPM's and much more.. Please "search" arround you'll find some interesting threads which will give you some basic idea on what people arround here "been there done that"
EDIT: And for your kind information sir, what you describe as a simple way to measure optical output of a laser is mistaken with the idea of Guesstimation, which is what we dont accept as an authentic way! So if myself or yourself needs to sell a laser, lets suppose we have the output in our DMM thermometer.. We just cannot say the output of my 445nm laser is 60Degrees Celcius..
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Last edited by sinner; 05-10-2012 at 03:59 PM.

05-10-2012, 09:37 PM #5
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netiks
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Re: Simple way to measure laser power

I was talking about temperature dissipation via cpu radiator but ok if you dont like this way you use another sir

05-10-2012, 11:12 PM #6
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Cyparagon
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Re: Simple way to measure laser power

Let me get this straight...

netiks: *pseudo-science drivel*
others: "won't work at all for reasons X, Y, and Z"
netiks: "If you don't like this way, fine"

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05-10-2012, 11:50 PM #7
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lasersbee
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Re: Simple way to measure laser power

Quote:
 Originally Posted by netiks Simple way to measure laser power If you have a multimeter with temperature function just drill a hole in the cpu aluminum radiatior and glue multimeter termocouple inside it ..after that you just need to calibrate it to show mw instead temperature with some resistor pot on termocouple
If you do a little research and reading on the Forum you will
see that a lot of effort has been out into finding a zero cost
LPM by some very knowledgeable Members in the Past...

You method of testing the temperature of a Laser's beam to
get a rational and usable Power reading is akin to sticking a
wet finger into the wind to test for wind speed in MPH...

Jerry
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05-13-2012, 12:55 PM #8
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netiks
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Re: Simple way to measure laser power

Cyparagon I'ts not your fault because Your to Dumb to understand how this works
Fnd some professional help!

05-13-2012, 12:58 PM #9
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cilegray
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Re: Simple way to measure laser power

Quote:
 Originally Posted by netiks ...
Not the best way to make friends around here... -rep

Last edited by cilegray; 05-13-2012 at 12:59 PM.

05-14-2012, 08:10 AM #10
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Fiddy
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Re: Simple way to measure laser power

Quote:
 Originally Posted by netiks Cyparagon I'ts not your fault because Your to Dumb to understand how this works Fnd some professional help!
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05-14-2012, 04:08 PM #11
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TheReddish
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Re: Simple way to measure laser power

I would not go so far as to call it pseudoscience, his concept is kinda right and with the right room temp and math, he could get a fairly good measurement, NO measurement is perfect, we don't have the ability to get a quantized measurement but what he suggests is not simple, you would need many different lasers at a known output and wavelength then you could start comparing data, the amount of work for me is not worth it and the prices on the entry level ones by members of this forum are insanely good for the accuracy, time = money so I would rather just buy one. but laser helmets and ion bracelets and astrology are pseudoscience and his idea is based in real physics.

to the OP don't get so upset though they sound mean, they are helping you even if you don't agree with way they are doing it, and its pointless to get mad online.

05-14-2012, 05:44 PM #12
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Cyparagon
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Re: Simple way to measure laser power

Uh huh, and I can measure current with a thermocouple. The current drives a fan which pushes air which hits the thermocouple which results in friction which creates heat.

Are we building a measurement device, or a Rube Goldberg machine?

It only works in theory if you ignore all the math associated with the theory.
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05-14-2012, 06:14 PM #13
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TheReddish
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Re: Simple way to measure laser power

"Using a thermopile sensor is a very robust and well established way to measure laser energy. The underlying principle is quite simple: it uses some thermocouples to measure the temperature gradient between the point where the laser beam hit the thermopile and the periphery where the heat is dissipated using a heatsink. It is then easy to calculate the incident laser power."

pretty close to what he is saying, not prefect and he does have a design flaw. If your going to pull the math card how bout showing me the equation that proves him wrong instead of just saying I got the maths smarts and you don't.

He never said he was a electrical engineer or a that he has mastered QED theory, so I see know reason to say anything to him but what he did wrong. I think a certain person that commented on this thread could tell him all he needs to know to fix his idea and get it working, but did they? You could shine a laser at coffee and measure the temp of the water change to give power of a laser with the right math. The best why to criticize him would be to show him whats wrong and how to fix it. Not call his idea pseudoscience.

anyway I should not be defending him after his little comment about you, so I will quit now, knowing we don't know is half the battle, go Joe!

05-14-2012, 06:22 PM #14
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sinner
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Re: Simple way to measure laser power

@TR: If supposedly we know The math associated, and variable's to consider would make it somehow possible..
But it will not be Practically used by a hobbyist, because we will need a whole Controlled Environment system just so we can get "close to original" measurement and those equations would make a normal guy go nuts..
I will again emphasize on the term measurement because when you talk about measuring a certain characteristic you must know it is correct..
I will prefer the IR thermometer or the OpenSource LPM project by trevor instead..
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05-14-2012, 06:43 PM #15
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TheReddish
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Re: Simple way to measure laser power

wow did he get banned just for that insult to you Cyparagon? or did I miss the real fun :P His comment about being dumb if directed at me would have produced chuckles, its like saying "I am not immature, you are, you poo poo head".
=

05-14-2012, 09:02 PM #16
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Cyparagon
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Re: Simple way to measure laser power

You know as much as I do about the ban.

Are we seriously still discussing this? Like I said in my first post, it's not linear. Therefore, you cannot use a DMM.

Think about this from an experience perspective. Point a 5mW laser at a CPU heat sink. What happens? Nothing. No detectable change in temperature. You might see 1C difference if you point a couple watts at it for a few minutes, but good luck finding equipment that has temperature resolution that low for less than a top-notch power meter anyway. Besides, with a response time that long, ambient light, ambient temperature, minor changes in air flow, laser instability, and who knows what else will make the reading useless.

Can we be done now?
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