Thought I would provide an update on the PWM to laser output testing.

Lasers
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1

Thought I would provide an update on the PWM to laser output testing.
As you know I embarked on a task to measure the K40 dynamically at the lasers output.

I built a PWM generator and that works fine as an adjustable source.

I also built a laser output sensor unit that used standard IR sensors like used in remotes.

As you know CO2 lasers operate at 10600 nm the high end of the IR spectrum. I had foolishly hoped that standard semiconductor optical devices (like those in remotes) would have SOME output at this wavelength and if I got the laser power attenuated, I would have a cheap way of measuring the light dynamics.

Nope… no output at the CO2 wavelength. Although one can purchase a lab sensor at this wavelength for lots of money nothing in the available semiconductor technologies have any response this high up.

I haven’t given up. I am now experimenting with some pyroelectric devices which I am not confident will have fast enough response, we will see.

Figured you were wondering what was taking so long :).

Suggestions are always welcome.

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I can’t say I understand most of what is in your article, but it is well written & presented. Glad to see someone doing some solid scientific analysis of the issues for the PWM. Keep up the good work Don :slight_smile:

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I currently ditched the 2 pin setup in favor of the 1 pin, pwm at the L pin. Why? Because at 21-23 deg Celsius my laser won’t fire under 5ma. At 4ma it fires but LPS screams weirdly. So I can safely set the pot at 5ma and use 50% power in LPS and guess what, I get lower output power, like 2.5ma, better for engraving at normal speeds which wont shake the machine apart.