Estimate the mW of my laser?

[trencheel303]

Focus it, and burn through black thin CD case. Then use formula:

Power(mw) = 1000/time(sec)

It's VERY rough, of course. From your description it sounds stronger then 70mW. Also 400mA is quite a lot ..

I have a feeling that formula is rather optimistic. I just tested with my 445 and I'd say it took about 2 seconds for the dot to appear on the beamstop. It probably only took a second or so for the beam to poke through (safety glasses, couldn't see) but that still places mine 600W underspec... possible, but I think unlikely.

Having said that, I've got my focus locked about 3-4 feet in front of the laser, so the beam at that point is probably a touch more divergent than if I'd focussed a mere foot in front of the laser. Still, I can't see it making that much of a difference, so maybe 2000/time is a slightly closer bet, or even 2500/time.

(but really, there are far too many variables to make it anything over than a wild guess)...

 

[DrSid]

I have a feeling that formula is rather optimistic. I just tested with my 445 and I'd say it took about 2 seconds for the dot to appear on the beamstop. It probably only took a second or so for the beam to poke through (safety glasses, couldn't see) but that still places mine 600W underspec... possible, but I think unlikely.

Having said that, I've got my focus locked about 3-4 feet in front of the laser, so the beam at that point is probably a touch more divergent than if I'd focussed a mere foot in front of the laser. Still, I can't see it making that much of a difference, so maybe 2000/time is a slightly closer bet, or even 2500/time.

(but really, there are far too many variables to make it anything over than a wild guess)...

Oh, you are actually right. I made the math wrong. I remember this cause my 200mW red does that in 10 seconds, and my other lasers according to this formula with about 10% error.

So it is indeed more like 2000/time.

I guess it also depends on the case, but I came over 5 different brands and the all acted the same.

It also not meant to 'measure' the power, but to give you very rough estimate. If you buy green 200mW which won't even smoke the plastic, you know something is wrong. Same if you buy 50mW which will blast through in 8 seconds. Both happened to me.