DIY Laser Power Meter

[drlava]

Hi, my first post.
What do you think about a single supply op-amp like the OPA344?

You should choose an amplifier with an extremely low offset voltage. The one in his schem. has 0.5 microvolt, where the OPA344 has an offset of 0.2mV (500x greater) If you find a single supply op amp with such a low offset and drift you should be OK.

Both the on-board preamp and the amp used in this design use sample-and-hold input op amps, which is what you should shoot for.

 

[knimrod]

Hi, my first post.
What do you think about a single supply op-amp like the OPA344?

The LTC1050 can also run with a single supply. It was just a simpler design to make everything work with a dual supply. I experimented with several op-amps. With these thermopiles, we are working with very high gains and nothing else I tested performed as well as the LTC1050. Drift was a real problem. The LTC1050 is ideal because of its low or "zero" drift characteristics and its low input offset voltage of 500nV.

 

[amkdeath]

good news: I ordered the thermopile, meaning I have no more parts left to buy!

bad news: I have $4 left in my checking account :-/

regards,

amk

cant wait to get this baby all hooked up and ready to go!

 

[YAGman]

Hi,
Wow, you people are good! Now you got me thinking about the MAX4209, not so bad on the drift (0.5uv/c). Interesting fixed gain (1000 +/- 0.03%). I may have to try one as I wait for the detector.
Next time I will read more of the data sheet before I respond.
bye,

 

[dkelley]

Yahooo!!!. I got my thermopile last night. Today I have a working laser power meter. I used the Radio Shak #270-1806
(6x4x2) box and put the thermopile and all electronics in the same box. Seems to work very well. Thanks for the putting
together the project with parts. Also thanks for the idea of reusing the connector from the original board. I too am interested
in the PC interface board. I think I have room in my current box to accomodate another outside connector or two. I'm
very pleased with the entire experience.

Thanks again
dkelley

 

[knimrod]

Pictures.. Must have pictures..

 

[amkdeath]

Pictures.. Must have pictures..

ditto

 

[TheMonk]

Knimrod,

I got the thermo senor + board no DPM yet.
How do I power up the sensor and use my MultiMeter (2v with 1mV increment, 1mV=1mW) to measure Laser power?

thanks
TheMonk

 

[roSSco]

Unless your meter reads micro amps you will have to build the circuit.

 

[TheMonk]

I have DX BT9205A, I can set it to 2m.

 

[amkdeath]

I got the PCB today, YAY!!! looks nice, good job man! just waiting for the components, thermal meter, and DPM...

I cant wait to measure my open can's output...

 

[TheMonk]

I have DX BT9205A, I can set it to 2m.

Yes, it can measure 1 micro amp.

 

[amkdeath]

[quote author=TheMonk link=1200112201/195#201 date=1203043685]I have DX BT9205A, I can set it to 2m.

Yes, it can measure 1 micro amp.[/quote]

not amps, you need volts. can it measure microvolts?

 

[roSSco]

Damnit, I meant to say volts.

 

[TheMonk]

The resolution is 100 micro volt. :'(

 

[knimrod]

Knimrod,

I got the thermo senor + board no DPM yet.
How do I power up the sensor and use my MultiMeter (2v with 1mV increment, 1mV=1mW) to measure Laser power?

thanks
TheMonk

Why not just build the board up and use your multimeter with the amp board until our DPM arrives?