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No access to any LPM owner; what's the most accurate and easiest to make DIY LPM?

Sepehr

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Lol. Or have a few set up in a way that triggering one causes another mounted on a servo to wiggle and lead to the next. Cat crosses beam, wiggly laser turns on, stuff ensues, entertained cat :p
LOL when I imagine a cute cat entertained and confused meanwhile playing with that! :D
 

astralist

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I see that you are an EE student, well then i'm sure you can build a TEC based LPM easily ;)

you could build a high powered LPM for only a few $$$
arduino based or something that can read the voltage and display it on PC or LCD
don't worry with the calibration though, there is many ways to calibrate your sensor ;)
 

Sepehr

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I see that you are an EE student, well then i'm sure you can build a TEC based LPM easily ;)

you could build a high powered LPM for only a few $$$
arduino based or something that can read the voltage and display it on PC or LCD
don't worry with the calibration though, there is many ways to calibrate your sensor ;)
Thanks! However I'm a freshman ;) so I don't know what "TEC" is?
 

CurtisOliver

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TEC stands for Thermoelectric cooler. They transfer heat from one side to another using the peltier effect. Depending on polarity, they can be used to heat up or cool down an object.
They are used in refrigerators.
 

Sepehr

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TEC stands for Thermoelectric cooler. They transfer heat from one side to another using the peltier effect. Depending on polarity, they can be used to heat up or cool down an object.
They are used in refrigerators.
Thank you :)
 

astralist

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Thanks! However I'm a freshman ;) so I don't know what "TEC" is?
TEC, or peltier, just like CurtisOliver said, it can be used to pump heat from one side to another.

And i might want to add something:
if one side of TEC/peltier fixed/glued (using thermal glue of course) then the other side can be used as a temperature sensor, thus it can be used as laser power meter.

long story short, if TEC supplied by voltage, it will pum heat from one side to another, producing one hot surface and one cold surface, on the other hand, if you exposed one side of the TEC to a heat source e.g laser, it will produce a small amount of voltage (Seebeck effect).
 

CurtisOliver

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TEC, or peltier, just like CurtisOliver said, it can be used to pump heat from one side to another.

And i might want to add something:
if one side of TEC/peltier fixed/glued (using thermal glue of course) then the other side can be used as a temperature sensor, thus it can be used as laser power meter.

long story short, if TEC supplied by voltage, it will pum heat from one side to another, producing one hot surface and one cold surface, on the other hand, if you exposed one side of the TEC to a heat source e.g laser, it will produce a small amount of voltage (Seebeck effect).
Precisely Astralist. Just need to calibrate it to work out how much power your laser is emitting using a already tested source.

http://laserpointerforums.com/f42/possible-just-possible-cheap-lpm-using-small-tec-s-first-experiments-43716.html

Edit: Just added an old thread from 2009.
 
Last edited:

Sepehr

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TEC, or peltier, just like CurtisOliver said, it can be used to pump heat from one side to another.

And i might want to add something:
if one side of TEC/peltier fixed/glued (using thermal glue of course) then the other side can be used as a temperature sensor, thus it can be used as laser power meter.

long story short, if TEC supplied by voltage, it will pum heat from one side to another, producing one hot surface and one cold surface, on the other hand, if you exposed one side of the TEC to a heat source e.g laser, it will produce a small amount of voltage (Seebeck effect).
What about low-powered lasers with no sensible heat?
 

CurtisOliver

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Ah, not good I forgot that yours are low powered. This method won't allow the measurement of lasers as low as 5mW unfortunately. Even a well built hobbyist lpm listed above won't read lasers accurately below 15mW.
 

Sepehr

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No problem. Very interesting project. Thank you guys for introducing it.
I'll definitely try to build one as soon as I'd have time for it.
 

astralist

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What about low-powered lasers with no sensible heat?
It depends, with right type of TEC, signal processing, and good environment, you can read down to sub miliwatt.
TEC with many PN junction (or small box if you see it from the side) has a higher output voltage per units of heat.

Just for example, i have these peltier which outputs about 300mV per watt laser (when coated with black matte surface).
I also have this one with fewer PN junction which outputs about 170mW per watt laser.

If you want to measure tiny powered laser, you should choose the one with higher output, and you might need to amplify it using high precision zero drift chopper amplifier
only then you can easily read the voltage using ADC from the microcontroller like arduino, etc.
 

CurtisOliver

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Could a hobbyist put together one that sensitive? If so, that would be super impressive.
 

astralist

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Could a hobbyist put together one that sensitive? If so, that would be super impressive.
My Hyperion LPMs are able to read down to 1 microwatt :eg:
the 22-bit ADC and signal processing allows it to happen :shhh:

still, when in doubt, i can always ignore something below 1mW :whistle:
 

CurtisOliver

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That is a very good reading accuracy. You've impressed. :p
 

lasersbee

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And i might want to add something:
if one side of TEC/peltier fixed/glued (using thermal glue of course) then the other side can be used as a temperature sensor, thus it can be used as laser power meter.
Actually the TEC/peltier in the seebeck configuration
is not used as a temperature sensor for LPMs.
It is used as a differential voltage sensor between the
front and rear plate's differential temperatures. :)

Jerry
 




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