Very high power pulsed laser diode array prototype :)

Last week, I have assembled a 20 W pulsed laser diode array for PIV with PIVlab. I just finished the first test and successfully measured velocities in air of up to 20 m/s with a small field of view (47x47 mm) and with the pco.panda 26 DS. The interframe time was 10 microseconds with a pulse length of 10 microseconds. Images with 25 megapixels (= no pixel binning) were captured. As the light intensity is pretty low at these short pulses, pixel binning is recommended however.

In water, this will give really awesome results, I will test it the coming week.

I was using a third-party laser driver for this test which isn't very good for such short pulses (laser light takes 2 microseconds to ramp up with this driver). So some light will be lost with this third-party driver.

With my own circuit, which uses the iC-HGP laser driver chip, this will become much better (only 150 nanoseconds ramp up time). But I'll need to use several of these chips to drive groups of laser diodes because they can't handle voltages about 12 V. I accidentally burnt one already because I forgot about this pretty important fact...

It seems also feasible to combine two 20 W systems to get 40 W in total. Lasers with this power output are totally dangerous, especially if the duty cycle increases above 10% and if the pulse length increases above 100 µs. So I am taking measures to limit these numbers with hardware watchdogs.

The 20 W pulsed laser prototype

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