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.