How I tried to measure laser power.

[Robert Silvers]

I once heated a known quantity of water in a microwave to calculate how much wattage was going into the water. This has been done to measure the power of lasers, and was suggested by Steve Hardy to heat 100 grams of water for 10 minutes in a vacuum flask (Thermos) and then the wattage is the temp rise * 0.7.

http://imageshack.com/scaled/1280x1024/842/98es.jpg
http://imageshack.com/scaled/1280x1024/191/o6hq.jpg

My water went from 19.83 to 37.78C in 10 minutes while the laser was at 26.5 mA.

So that is 12.5 watts.

This does not seem to be working. Maybe the water is reflecting much of that beam. Or maybe water vapor is absorbing the beam.

Has anyone compared these $100 meters to an expensive laser power meter?

[Dan Hintz]

This is a woefully inaccurate experimental setup. Calorimeters are highly controlled devices, typically with double-walled vacuum insulation, small entry areas, etc. You're basically bleeding off your heat to the environment before you can measure it.

[Robert Silvers]

This is a woefully inaccurate experimental setup. Calorimeters are highly controlled devices, typically with double-walled vacuum insulation, small entry areas, etc. You're basically bleeding off your heat to the environment before you can measure it.

Really, because this one has no insulation at all:

http://www.macken.com/laser1.shtml

It works because it is calibrated to compensate for the losses.

If I had an actual laser power meter I could adjust the formula to work as well as the Macken.

[Dan Hintz]

Really, because this one has no insulation at all:

http://www.macken.com/laser1.shtml

You also don't run them for 10 minutes, all of the while energy is slipping back into the environment. They're also calibrated (within reason) to handle a certain amount of energy loss to the environment.

I'll be honest with you, Robert... it seems like no matter what the topic is, you argue against whatever I tell you. I can understand a certain level of skepticism, but your responses go beyond that and right into complete challenges. I have better ways to spend my time...

[Robert Silvers]

You also don't run them for 10 minutes, all of the while energy is slipping back into the environment. They're also calibrated (within reason) to handle a certain amount of energy loss to the environment.

I'll be honest with you, Robert... it seems like no matter what the topic is, you argue against whatever I tell you. I can understand a certain level of skepticism, but your responses go beyond that and right into complete challenges. I have better ways to spend my time...

Actually you are the one who argued against what I said by calling my setup "woefully inaccurate" due to heat losses (that is not a challenge?)

So yes, I just had to point out that the professional setups also had heat losses, and that the difference was the calibration (time of measure and multiplier).

[Dan Hintz]

Actually you are the one who argued against what I said by calling my setup "woefully inaccurate" due to heat losses (that is not a challenge?)

So yes, I just had to point out that the professional setups also had heat losses, and that the difference was the calibration (time of measure and multiplier).

Okay, if that's how you wish to approach these things. I wish you luck, but as I mentioned last week, I'm tired of my hand getting bitten every time I try to feed you. Time to look for handouts elsewhere as I will no longer be offering bread.

[Rodne Gold]

I think you should use your laser to do stuff rather than try reinvent the wheel and show us your testing methodology - all of us really know what the lasers are capable of and have given advice to you on how to run them. What actual purpose is there to this test ? You got what you got and it is what it is ...If you think you have been done in by Reci re power or with your chiller re maintaining a temp or your supplier regarding the optic or whatever , perhaps take it up with them...

[Robert Silvers]

Okay, if that's how you wish to approach these things. I wish you luck, but as I mentioned last week, I'm tired of my hand getting bitten every time I try to feed you. Time to look for handouts elsewhere as I will no longer be offering bread.

You still don't see what you did. Your initial reply was condescending. Because it was also incorrect, I replied back in a challenging way. Had you just been incorrect and not also condescending, I would not have replied with a challenge.

[Robert Silvers]

What actual purpose is there to this test ?

To see how many watts my laser is emitting. It didn't do that, but that was the purpose.

[Rodne Gold]

How exactly will that help you? As I said , you got what you got and it is what it is.... do you think you have been the victim of fraudulent misrepresentation?

[Dave Sheldrake]

Robert,

You seem to constantly be looking for verification of erroneous statements then disagree with those who respond with factual data.

Why do you think Ophir etc DON'T use tubs of water in their meters? (and that's not a question as I have little to no interest in the response)

The bottom line is you have owned a laser for a matter of weeks, are trying to reinvent the wheel,disagreeing with what people who have decades in the industry are saying and have no formal qualification in the subject matter you are so forthright about. It's akin to posting "I know the earth is flat" then arguing with anybody who says otherwise because the answers don't fit your pre-defined expectations.

I don't post in the wood turning section, you know why that is? because I don't know anything about it past what I see, I'm not a wood turner, I don't own a wood lathe and am not in the turning market or business.

It comes across as arrogant!

It would be like me trying to tell Keith Outten he knows nothing about sign making or telling Dyson (not the guy that makes vacuum cleaners either)he knows nothing about nuclear propulsion or Teller (RIP Edward) his silly bomb design will never work. You even went so far as stating all the worlds Laser manufacturers are using the WRONG terminology for PPI.

Take this


To see how many watts my laser is emitting. It didn't do that, but that was the purpose.

The most bassist of physics understanding would tell you it WILL NOT WORK for a number of reasons and yet your argue physics with people eminently qualified IN Physics based on belief.

I'm totally with Dan on this, I'm not wasting any more of my time trying to educate somebody incapable of understanding.

David

[Mike Null]

I don't know whether I should agree or delete a couple of these posts but I have to say that my impression is the same as Dave's and Dan's and I think it's time to say so. My boss may disagree but he closed the salt mines a while back.

[Robert Silvers]

How exactly will that help you? As I said , you got what you got and it is what it is.... do you think you have been the victim of fraudulent misrepresentation?

I am an experimenter and like to make charts. I tried this with a microwave. I like hour meters. No, I don't have any feeling that I am a victim of anything.

[Robert Silvers]

If I get a laser power meter, and this experiment with a calibrated formula is within 10% of what it indicates at both 50% and 100% power in a reproducible way by someone else, would you change your mind about this not working?

[Mark Sipes]

I think I will go engrave some sugar cookies for Halloween. They were a hit last year!

[Robert Silvers]

I put my dog's name on a stack of Milkbones - it was a good way to try the matrix engraving feature.