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Laser pointer power dissipation


New member
Feb 1, 2021

I was wondering if the power drops as the laser is on. I have a green laser pen that’s probably around 50 - 100 mW and I’m trying to find out how much power it does have without a power meter.
So I was popping black balloons and gradually increasing the distance fro balloon to laser. After a few minutes the laser seemed to lose most of its power and I couldn’t even pop a balloon from inches away.

the 18650 battery still reads 4volts so the battery has not gone down much at all.

is the power lost as the laser remains on from heat or anything else?

also with my safety goggles I can’t even see the laser beam or dot when on something dark like a black balloon. If i take the goggles off to see the dot on the balloon am I at risk?

thanks for any info. I’m a newb pretty much when it comes to lasers.