Scientech 372 Laser Power Meter @ JWC.blog
This is a copy of the post on my blog about the power meter I got from Laser_Ben this weekend. I apologize for any errors during copying.
This meter has a thermopile detector (as opposed to the photoelectric sensor on my Liconix 45PM) and can measure up to 10W. Last spring, I purchased a large-aperture (100mm!) calorimeter that can tolerate up to 50W; that unit will work with this meter as well. Thermopiles are becoming very difficult to find nowadays, so I was more than happy to shell out $150 for the unit. Prices on eBay range dramatically (the meter alone sells for about $150 sometimes, but I’ve seen them for as low as $50).
My Liconix 45PM (top) uses a photoelectric detector and reads up to 100mW. It is pretty effective for watching how power output fluctuates as the laser warms up.
L: 50W thermopile, T: photoelectric detector, R: 10W thermopile
Anyways, after verifying that the meter worked, I started to investigate the meter’s output for an analog recorder (this thing is old…). I hooked up a multimeter to the output terminals (okay, I didn’t have any banana plugs on me, so I made some with tinfoil).
This meter has a thermopile detector (as opposed to the photoelectric sensor on my Liconix 45PM) and can measure up to 10W. Last spring, I purchased a large-aperture (100mm!) calorimeter that can tolerate up to 50W; that unit will work with this meter as well. Thermopiles are becoming very difficult to find nowadays, so I was more than happy to shell out $150 for the unit. Prices on eBay range dramatically (the meter alone sells for about $150 sometimes, but I’ve seen them for as low as $50).
My Liconix 45PM (top) uses a photoelectric detector and reads up to 100mW. It is pretty effective for watching how power output fluctuates as the laser warms up.
L: 50W thermopile, T: photoelectric detector, R: 10W thermopile
Then, I could read the voltage drop across the terminals (which was in the 0-100mV range). I then (manually…) tried to establish a relation between this voltage drop and the reading on my meter. After taking a bunch of samples, I had data with some pretty decent correlation.
I suspect that the error is the result of an inability to accurately read the meter. However, the R value is pretty high, so I’m happy with the estimate. After that, it was just a matter of testing a few lasers.
I’m quite happy with the results. The green module I purchased for my Triple Play laser set was originally rated to be 50-60mW; I’m glad it exceeded the rating consistently. The PHR is also doing quite well at around 95mW.
I’m a little curious as to why the readings all have a sharp drop at about 30 seconds in. Also, the Scientech meters try to compensate for calorimeter warm-up time by overshooting in the very beginning, but this gives very inaccurate readings (my greenie started at like 150mW at one point); so I cut that part out of the readings.
I’m going to test my lasers more thoroughly when I get a chance; I’m excited to see how my SKY operates (my batteries were almost empty when I tried, so I didn’t get very good stability).
You can also see all those pictures (some with more descriptive captions) in my growing Laser Pictures album.
