anyone made a lpm?

any one made a laser power meter? curious what sensor i can shoot a laser beam at, read its value, print it to a lcd. needs be pretty accurate say 10mw to 1w(maybe lessb

found sensor... a thermopile but which one can handle this range?

Hmm, Would you have to measure power in a very very cold dark room though with one of those?#

I would also be interested in a way to measure the output power, just out of curiosity as to what the ones I have areā€¦

Mowcius

No, somehow you'd have to tie it to a heatsink and shoot the beam against it but the surface must be coated black and can handle a high temp that wont burn through

I am currently working on a laser power meter based on the Arduino.

To measure laser power accurately you need to purchase a thermopile head specifically designed for lasers. They typically output around 1mv/mW, which is easy enough to read with the Arduino.

Depending on the thermopile and lasers you want to meter, you will loose resolution running it up to max power (5W laser power), so I have been using the ATMega's internal 1.1V reference as a low power mode, which reads 0-1.1W laser power at about 1mv resolution, and then once it reads over 1.1W it automatically switches the voltage reference to 5V.

How good would a thermopile be for low power lasers? I suppose you need a different method. I presume you need to measure the light output then rather than the temp becuase a laser less than 5mW wouldn't provide much heat!

Mowcius

If you get a thermopile head specifically designed for laser power metering, then it should be good right down to 1mW. The problem with using light is that ambient light will effect your readings, and most light cells aren't all that linear.

I too have wondered how it could measure below 5mW, but it seems to work somehow ..

Yeah I am looking to measure accurately >5mw, mainly measuring less then 1mw...

I could do it in a completely dark room. I will have to have a fiddle with some photodetectors and LDRs etc to see what I can get. If I can compare between a good 1mw laser and a cheap 1mw laser then I can get an idea of power difference at least.

Mowcius

maybe a tapered hole inside the heatsink etc and focus the beam of light in it. then it would have enough darkness area to read it? what setup you using?