I had an idea for a project the other day. For my job, I have to test lasers on a power meter to see if they're strong enough to sell. But I'm wondering if the lasers are shoddy enough that the power reading goes down over time. Since I don't want to sit down for half an hour and write down the reading on the power meter every 10 seconds, I thought, I should write a program that can do this!

My problem is, I don't exactly know where to start. I've thought through a few options - I can buy some kind of power meter that connects to a usb port and write some code in C# or Python that can easily take a reading from the power meter (easiest option); I could use my Arduino to set up something like what leafy did, and interface to it with C# or Python (coolest option); or, I could do something else I haven't thought of.

Any ideas?

Check to see if the power meter manufacturer has any documentation on computer interfacing, that would give you a good start.

The power meter you have may have some sort of interface already-take a look at the back to see if there's a interface there.

Are the lasers supposed to work continuously? There might be thermal issues to keep it turned off most of the time.

Excellent points and questions from rfdave. Do you mean beam intensity (what I assume you mean) or power consumption (probably not the issue)? An Arduino piping serial data to a simple Python program generating a CSV you can display in GNUPlot or Excel is the easiest option, particularly if you already have an Arduino on hand.

Yeah, I'm talking about beam intensity. And the power meter I have is just a portable device - it can't connect to a computer (read: without extensive modification)

I'm not entirely sure if the lasers are intended to be used continuously. But I do think the people who buy them will have them on for at least ten or fifteen minutes at a time. That's mainly my reason for testing this, to see if the beam intensity changes over that kind of a period of time.

On a related note, how do you connect a power meter to an Arduino?

Can you help us out with a manufacturer and model number, or a datasheet? Does it have any visible output/interfacing ports, or just a digital readout?

UUhhhh we're talking about a power meter that doesn't exist yet. This is the one I have: http://www.sperdirect.com/cgi-bin/item/840011/LaserPower/Sper-Scientific-Pocket-Laser-Power-Meter And I'm pretty sure it can't connect to an Arduino.

According to the user manual for that device, there are no external interfaces of any kind. I suppose you could mod the device by taking a look at the board and finding some places to pull out a serial signal or even just a 7-segment encoded signal you could decode with an Arduino, but you might not want to rip the device apart. Another horribly over-engineered solution would be to use a webcam to take a picture of the screen every N seconds and use image processing to figure out what the numbers say. I definitely don't recommend that one. That leaves us with looking for an intensity sensor you could connect to your Arduino.

Hahaha that webcam one sounds fun but there is no way in heck I'm spending that much time on a dinky project like this And I'm not really supposed to tear apart the power meter. But if anyone has any suggestions on a power meter I can buy, let me know.

For a quick and dirty solution, you could grab one of these intensity sensors and interface it to your Arduino:

https://www.sparkfun.com/products/9768

Throw together an FFT (or basically even a simple pulse counter), calibrate it against your real meter, and voila.