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FrozenGate by Avery

Simple Laser Power Meter Using IR Thermometer

Yea, it makes a good comparator and can tell you % IR.
I needed one for draft finding since we've been doing outside remodeling.
Just make sure the "target" blocks the opening to the sensor.
If you had a piece of aluminum sheet stock .010 or a soda can cutout painted black the worst that 445 could do is fry the paint.

Just used as a comparator, I don't see the need for keeping the target size. It will take longer to heat and low mw like that 5mw red may not register for a long time or at all.
With the 3.13 multiplier, the 5mw 660nm raised the target 1*.

I have done some with 3 of my 532nm pointers and it's easy to see which one has the best output. 405nm pointers too. I was amazed the 532nm's were so high in IR. I expected abt 30%.

Like I said it was fun and informative.
If you have no LPM at all it can tell you quite a bit.
Someone with a calibrated LPM and a low and high mw laser would be interesting to see how it fairs out.
My guess is you'll have a different multiplier do to all the variances to hit the on spot output number.
 





Good Job on the build and Testing criteria Vaporizer...
Logical and well presented...:beer:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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Thanks Jerry.
I tried to get as much out of it in a methodical manner as possible.
You actually need 2 calibrated lasers, a calibrated LPM, or both to verify it as even considering using the "mw" for any reporting purposes. As a comparator, it will do for %'s just as it will for % of IR.
It was interesting though. I did read a filter test abt using 2 to indicate the loss due to the filter element itself. Adsorption & reflectivity. So I need to repeat the IR and do that. It could be the IR isn't as bad as indicated.
I'll post that retest result when I do it.
 
I tried this last night. My results with a 445 at 1000mA yielded only 212VmW (Vaporizer milli-watts). The paint was burning off.
 
dnar, did you read the thread? Those should be "Warske mw's". :crackup: He did the work.
There was mention if the paint wasn't thoroughly dry or having a focused beam could fry the paint. Of course this is also dependent on if the paint can take the heat level to start with. :whistle: With 1W of 445nm that's gonna be hot. :gun: :eg: Sounds like you might need header or barbecue paint and then you may still need that larger target I mentioned so you can defocus the beam enough to not fry it. The magic 3.13 number would need recalculated though if the target size is changed. If you have a real LPM, easy enough to create the number for you target.

You are basically reading the heat of the target difference after 30 seconds and using his number. A change of 1* = 3.13mw. At 20 seconds with a smaller "standardized" target it was usually stabilized in temp.
So you could possibly defocus the dot to near full target and still use the 3.13 if you can keep the paint on. :crackup: Also, I think he used 20cm as the firing distance.
 
could this work as a rough calibration, if u set ur laser diode to just above threshold and used the datasheet for the expected mW output to get the multiplier for the thermometer.
 
I thought abt that using a 635nm diode set to 30ma which should be 5mw.
Since it can vary from the manufacturer tolerances, lens loss, meter, the target size thickness, paint, drafts, on and on... I can still see room for errors if calling it an actual number in power. Comparison in a % value, I have no problem as they all see the same errors.
If the 5mw setup read 4mw you make a new number so it calculates out to 5mw. You just corrected 20% even though it was only 1mw. 20% error on 100mw is 20mw and 200mw on a 1W.
Without a standard/s for reference I just don't see it as "this is what it really is".

Edit: Also, I wonder abt the target size per mw max. For low power tries and comparison I can see this, but in a case like dnar's I would question if the target that size & thickness can even handle 1W of heat even if the paint survived. That is a tremendous amount of heat on a .500sq/in target. Mine was .002 thick, the authors was .007. LPMs use a heat sinked target. I would have to conclude just by reasoning that this target has a heat saturation point and will have losses or errors. If a person had a calibrated laser at 10, 50, 100, 200, 500, 1000mw you could possibly see if the target had a saturation point by % accuracy of a known.
I still think its a great experiment though!
 
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Just thinking aloud, how about using a photographic lux meter with low power lasers? Can the power be correlated to LUX? If so, could the actual power of a moderate power laser then be determined and then used to determine the calibration value for the IR meter?
 
From what I've read in the past.. LUX meters are not suitable
since they measure full spectrum light.. I'm not sure if any readings
of different wavelengths would even be the same...


Jerry
(8200-318-28398)

You can contact us at any time on our Website: J.BAUER Electronics
 
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I'm pretty sure that lux meters will also give different readings for 5mW green or read light. They're compensated along some kind of curve IIRC.
 
Good question dnar. I thought I had a light meter in my camera bag. Hmmm...maybe my daughter "borrowed" it. I was wondering if it could read a laser output without damaging the sensor or maybe even set in side a box to block ambient light with the inside box reflective so the laser would be the only illumination in the box. The light meter could read the inside via a hole for the sensor and the indicator be outside so you could see the reading.
 
It seems you are running around in circles....

You want to calibrate the IR thermometer DIY LPM with a calibrated
LPM but you don't have one.... so you will use a lux meter as the
calibrator but you need a calibrated LPM to calibrate the lux meter
but you don't have one....and so on and so on...

I'm not trying to shoot down your theory or be a PITA but it seems
like you will need a calibrated LPM to be sure of your findings one way
or another...IMO..:yh:

That's the way I see it... maybe I missed something...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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LOL, that seems to be the conclusion with any use other than a comparator Jerry.
One of those, "you can't get there from here". At some point if you want to try to use the readings, you have to have a known standard to calibrate it and then you still don't know the upper limits of accurate readings without testing it against a known unit.

Pretty much a tail chaser for anything other than a low cost comparator.IMHO
 
lasersbee said:
It seems you are running around in circles....

You want to calibrate the IR thermometer DIY LPM with a calibrated
LPM but you don't have one.... so you will use a lux meter as the
calibrator but you need a calibrated LPM to calibrate the lux meter
but you don't have one....and so on and so on...

I'm not trying to shoot down your theory or be a PITA but it seems
like you will need a calibrated LPM to be sure of your findings one way
or another...IMO..:yh:

That's the way I see it... maybe I missed something...


Jerry
Click to expand...

Not quite.

What I mean is this, if someone with a LPM can confirm what xyz mW confirmed by LPM relates to in lux then perhaps we could have a method that is reliable...

In the end, I am sure me and others will just admit defeat and buy an LPM.

Care to offer me a good deal?

Wayne.
 
Any updates on this project? Has anyone compared it to a real LPM and checked how close the power value comes out to be to the actual value? I have all the parts to build this thing, but I was hoping someone would be able to calibrate it and tweak that magical number to yield more accurate power readings.
 
dnar said:
Not quite.

What I mean is this, if someone with a LPM can confirm what xyz mW confirmed by LPM relates to in lux then perhaps we could have a method that is reliable...

In the end, I am sure me and others will just admit defeat and buy an LPM.

Care to offer me a good deal?

Wayne.
Click to expand...

Hey Wayne....

The best deal on any Laserbee product is right here on the
Forum.. Check the links in my Sig..
There is a LPF Memers Discount on selected products...
Sometimes we also put an LaserBee up on eBay but the LPF
discount can't be used on eBay...

I would offer you a used one but we haven't had any returns
since we started selling the LaserBee...
The last used ones we sold on the Forum were Shop Prototypes
and were sold with that understanding..

Keep a lookout for a Xmas Special....;)


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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