How is power measured in mW?

Is it by laser heat or the laser brightness?
And what about beam diameter? As it gets bigger power decreases. All lasers have different beam diameters.

Would you be able to make a meter with a photoresistor? (including some other parts)

Well, laser heat and brightness are proportional. So same thing You get meters measuring power in brightness and heat.

Beam diameter doesn't change anything. As the beam diameter increases the power doesn't decrease. It stays the same. However the power per area decreases. Power per area is something important for burning, more power per unit area the more burning power you can do, that's why you need focused lasers for that.

No ones come up with an easy DIY meter yet, and we've been trying Either buy one for a few hundred or send it to a member who can test it for you

You could make a DIY devise that will display a reading that may be helpful in comparisons between various lasers.
Say you bought two DX200mW & wanted to keep the more powerful one.
Or you built two blue ray lasers & set the driver current at 150mA on both, you could take a reading to establish
which one had the more powerful diode.

Murudai said:

No ones come up with an easy DIY meter yet, and we've been trying Either buy one for a few hundred or send it to a member who can test it for you

Click to expand...

i was wondering about this....do you recommend someone on here you can trust and who is willing to test for free?

Well I can test it for one, there are plenty of people who are trusted and will test things for you.

But you should always find someone close to where you live, saves on shipping costs and time. So... where do you live in this big wide world of ours?