How to make LPM?

[deltawars]

Hi i'm new to the forms and laser making so i'm sorry if this has already been asked or if i have posted it in the wrong section.

Does anyone know how to make a LPM on the cheap?
I don't really care about the accuracy as long as is fairly accurate like in a 200mw range as i'm going to use it to measure high power lasers.
I also have a arduino and i am familiar with the code(not sure if that helps?).
and one of my hobbies is electronics so i'm not a total noob lol.

P.S sorry if i made some spelling mistakes or wrote anything back to front i posted this just after midnight

 

[Livinloud]

send a message to ARG......he can help you out and FYI 200mW is not high powered

 

[deltawars]

thanks for the info ow and sorry i meant it can be 200mw off like say the laser is 2500mw it would register 2300mw

 

[Livinloud]

oh yeah that makes sense now that i re-read it. if you buy or build a LPM that can be 200mW off then you have a piece of junk LPM......an ophir at 2.5W at most should be 125mW off if its 5% off. anything more than 5% is junk and not worth the time or money. Most ophir should be within 1% if not spot on.

 

[Cyparagon]

Any metrology enthusiasts will tell you there is a big difference between 1% and spot-on . I think the ophir heads are 3%-class devices.

 

[Livinloud]

you got my point though

 

[ARG]

DIY Ophir setups can run you around $200-300 which is really good considering the surplus heads are around $700 new. Best deal going IMO. Plus you can always expand later on.

If that is too much, try this DIY thermal LPM for under 50$
http://laserpointerforums.com/f42/diy-thermal-lpm-under-50-a-51129.html#post704325

 

[Bionic-Badger]

Note that the "$50 LPM" is nothing more than an amp that provides a reading. You'll need to get calibration data about your sensor so that you know what that reading actually corresponds to (e.g. the power). Once you've bought on a sensor maybe you can get someone on the forum to perform tests on it to get you that calibration data.

 

[ARG]

A stable laser with a known power can be used as well.

 

[Bionic-Badger]

I think you'd need two, or a tunable laser to have at least two datapoints.

 

[ARG]

It would be a good idea, to account for any non-linearity.