Hmmm... Well I'm looking for a laser that can work continuously for an hour or so at a time at as low of a power as possible so I can use batteries. Any recommendations?

 

You may refer to the pwm circuit as below, it can be adjust the output current, I used 5mA for zener diode and 20 mA for Laser diode, the total current is 25mA, so it won't exceed the laser diode needed.

You can measure the current of Zd1 and Laser diode, and adjust the R2 value to get the properly current and also not exceed the rating current 25 mA of Laser diode, I used 20mA, because it was 80% of 25mA.

You can also using the 555 Astable Circuit Calculator to calculate the frequency.


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You could squeeze a bit more power out of that by using pulse operation.

Find out the LD peak pulse current and recalculate the 30R resistor to drop 0.7V at that current, then feed that volt drop to the B/E of a transistor who's collector switches the 555 reset pin.

 

You could squeeze a bit more power out of that by using pulse operation.

I thought about that, but since this is a pwm and it can be adjust close to 100% that it will exceed the rating current of LD, if limiting to 50% then it will match what you mentioned.

Find out the LD peak pulse current and recalculate the 30R resistor to drop 0.7V at that current, then feed that volt drop to the B/E of a transistor who's collector switches the 555 reset pin.

Thanks, that is a good idea.