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My DIY laser powah meter

Hiemal

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Hey all.

I recently made a laser power meter, since today my voltmeter came in from eBay.

I got the peltier device from my electronics teacher, and it seems to work pretty well. I made it so that you can choose between 10x gain or 100x gain, so you get a more or less accurate reading, depending on how much power you're attempting to meter. Circuit is just a basic op amp voltage amplifier... Can choose between a 10k ohm resistor (10 gain) or 100k ohm resistor (100 gain).

Here's da video; DIY Laser Power Meter - YouTube


Though, 273 mW seems a lot overspec for a laser that's only supposed to be 200 mW.... :p

I measured my blue before, and it was around 550 - 600 mW or so. It's running at around 500 mA, so it seems pretty efficient!


Thanks for watching! :D
 
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Hiemal

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I haven't really got anything to go off of calibration to be frank. :/ I just zero'ed the meter, and tested it out....

I got nothing to go off of in regards to calibration.
 

Wolfman29

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My recommendation - once you get the 405nm laser working, send both your 405nm laser and your 650nm laser off to someone with a calibrated LPM (there are tons of 'em in the NE). Then, calibrate your LPM based off of those two readings.
 

Hiemal

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I probably will, actually. Just gotta find someone, and finish my builds. :p
 
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rhd

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My recommendation - once you get the 405nm laser working, send both your 405nm laser and your 650nm laser off to someone with a calibrated LPM (there are tons of 'em in the NE). Then, calibrate your LPM based off of those two readings.
Oh gosh. I'm not sure I'd take that approach. That's dangerous.

A portable diode based laser, even two, shouldn't be used to calibrate an LPM that you're going to then use in the future.

Portables can vary by quite a bit depending on all sorts of things. Batteries, temperature, lens cleanliness. Even the shipping process can disrupt a portable build. If ANYTHING, send your _LPM_ to someone with a known stable calibration source. Have them calibrate your _LPM_ and send it back to you.
 

Wolfman29

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Well, obviously a DIY LPM is never going to be perfect. However, if you try to control as much as you can, it can be pretty accurate. My DIY LPM is calibrated nearly exactly as a Laserbee is just after numerous trials of calibration (using a bunch of known, but DIODE-based lasers).
 

lasersbee

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Hey all.

I recently made a laser power meter, since today my voltmeter came in from eBay.

I got the peltier device from my electronics teacher, and it seems to work pretty well. I made it so that you can choose between 10x gain or 100x gain, so you get a more or less accurate reading, depending on how much power you're attempting to meter. Circuit is just a basic op amp voltage amplifier... Can choose between a 10k ohm resistor (10 gain) or 100k ohm resistor (100 gain).

Here's da video; DIY Laser Power Meter - YouTube


Though, 273 mW seems a lot overspec for a laser that's only supposed to be 200 mW.... :p

I measured my blue before, and it was around 550 - 600 mW or so. It's running at around 500 mA, so it seems pretty efficient!


Thanks for watching! :D
Did you get a power certificate from Lazerer for your 200mW
rifle Laser....:thinking:
If so what does the certificate show as output of that Laser...:thinking:

I'm fairly sure that Lazerer tests all the Lasers he sends out with
and without certificates since he knows that a lot of LPF members
own a Laser Power Meter.

I would adjust your LPM closer to 200mW or to what your power
certificate states. As I see on the Video... I would estimate that
your LPM reads ~35% too high..

I assume you used the single rail DIY LPM circuit that MM posted.

You can not pre- select the Gain as 10X and 100X if you don't have
a fixed.. calibrated and known input. The Gain is what is used to
calibrate your LPM. Then once it is calibrated you can use the zero
control to zero out your display

You may also get erroneous readings using different wavelengths
if your coating in not close to broadband.


Jerry

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

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Yeah, I thought about that for a little while before I realize that the gain was something that calibrates the reading... (though, the meter itself has a calibration pot, so I can turn that for some calibration)

I'll be modifying the circuit when I get home to add some potentiometers to allow adjusting of gain. I'll then find someone to *hopefully* calibrate it against a known and decent laser power meter such as a laserbee.

The Lazerer rifle I got didn't come with a power certificate, unfortunately. I really wish I had something to calibrate it off of. :p
 

offroadfreak8582

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Did you get a power certificate from Lazerer for your 200mW
rifle Laser....:thinking:
If so what does the certificate show as output of that Laser...:thinking:

I'm fairly sure that Lazerer tests all the Lasers he sends out with
and without certificates since he knows that a lot of LPF members
own a Laser Power Meter.

I would adjust your LPM closer to 200mW or to what your power
certificate states. As I see on the Video... I would estimate that
your LPM reads ~35% too high..

I assume you used the single rail DIY LPM circuit that MM posted.

You can not pre- select the Gain as 10X and 100X if you don't have
a fixed.. calibrated and known input. The Gain is what is used to
calibrate your LPM. Then once it is calibrated you can use the zero
control to zero out your display

You may also get erroneous readings using different wavelengths
if your coating in not close to broadband.


Jerry
Well i find lazerer's certificate not allways acurate enough to calibrate your lpm on. I have heard a couple of people whom retested there lasers and got different readings then the powercertificate from lazerer.

I suggest you send your lpm to a member called "bluefan" He recoats and recalibrates lpm's all the time so i guess that if he has enough time and you pay him you wil get youself a calibrated lpm :whistle:

He has a stable source of 447nM 1.0002W

For example he calibrated my basic lpm so that when he applied that power my lpm showed the 1W reading. ( calibrated for spectral range of 400nM to 1100nM)

greetings,,
 
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lasersbee

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Well i find lazerer's certificate not allways acurate enough to calibrate your lpm on. I have heard a couple of people whom retested there lasers and got different readings then the powercertificate from lazerer.

I suggest you send your lpm to a member called "bluefan" He recoats and recalibrates lpm's all the time so i guess that if he has enough time and you pay him you wil get youself a calibrated lpm :whistle:

He has a stable source of 447nM 1.0002W

For example he calibrated my basic lpm so that when he applied that power my lpm showed the 1W reading. ( calibrated for spectral range of 400nM to 1100nM)

greetings,,
Hmmmm that's funny I bought a 1Watt Rifle with certificate and it
was within 1% of the certificate when I Measured it on our Lab
Newport 1825c that we use to calibrate all our LaserBee products.
In fact is was 1% higher that the certificate when we measured it.

That would be more than good enough to calibrate a DIY LPM...

It would also cost more to ship to a member in Europe round trip
than to find a member in the same country.


Jerry
 
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