Any experience with a Ophir 150C-A OEM Head

[matratzki]

Hi,
I bought myself an Ophir 150C-A-.1/ERB Powersensor to build a LPM.
Today I tested the head with one of my Multimeters and found out, that it displays 0,1mV per 1mW.
Would it be possible to change it to 1mV per 1mW with one of the build in trimmers?
Did anybody make any experience about accuracy or tried to hook it to an arduino board?

Mathias

[-bart-]

Hi,
Would it be possible to change it to 1mV per 1mW with one of the build in trimmers?
Did anybody make any experience about accuracy or tried to hook it to an arduino board?
Mathias

I wouldn't touch the pots, as it voids the factory calibration.
These are factory calibrated for 1064 as recall. Although not for visible, it *is* a calibration, that lets you compare it to other identical heads.

I recall this member made his own power meter with a microcontroller and lc display.
Don't know if he visits the forum these days.

When integrating it in your own development you'll have to add an analog gain/bias circuitry and external quality ADC to achieve anything decent.
Also, as I have stated before, don't underestimate the usefulness of an analog readout by moving coil meter.

This sensor is as linear as any pro-device. Adding your own controller allows you you make all kinds of calibration tables if you have access to calibrated meters and/or standards.

[matratzki]

Hi,
I found out, that it was calibrated to a custom desiered wavelength of a CO2 Laser, up to more than 20W. But my first tests showed that the displayed data matches quite well with my second powermeter, also with visible wavelength.
I will try to contact him, propably he can give me some advieses. My plan is, to build just a small powermeter with LCD and datalogging function... Yesterday I did some research and found some very interesting projects based on arduino boards in the laserpointerforum.

Propably I try to add an op Amp with an amplification factor of 5. So I get 0,5mV /mW ... I do not need to measure more then 10W, so the outputpower of the ophir head would be in the range of 0-5V and this would perfectly fit to the input range of the analog input of an Arduino board.

[-bart-]

Maybe you can make the aduino switch the gain-stage for increased resolution.
0-100mW 0-1W 0-10W or even add auto-ranging.

[Picasso]

I found this one. Never built it, but the csshih guy has one. ignore the batt charge section to keep it simple.

[Robin]

I added some basic instructions on using these meters to the wiki.

[chad]

I added some basic instructions on using these meters to the wiki.

Thanks for adding that to the wiki. I tried in vain to get people to add some stuff.
chad

[ARGLaser]

You can use a 16-bit ADC with a low reference voltage (1.024) to get a digital read out from these without modification or using OP amps.