ednisley
April 3, 2023, 12:33pm
16
Depending on how the controller generates the analog output, it may have a lower bandwidth than the PWM output, which translates into slower response for small features. Unless you know for sure the controller uses an actual DAC with a proper reconstruction filter, use the PWM output.
I blathered on about that a while ago:
In principle, it makes no difference: the HV laser power supply will accept either analog or PWM signals. It has an internal low-pass filter to demodulate the PWM into the analog control signal it uses to set the tube current.
However, the controller generates its analog output by filtering its PWM signal, so feeding that to the power supply means it gets filtered twice and has a lower bandwidth.
This might begin to matter when engraving dithered photographs at high speed, where the laser must…
It works pretty much like you’d think:
[IMG_20221108_162508_HDR - Sine bars - acrylic - 100 mm-s 25pct]
That’s from a sine-wave test target with 1 mm cycles:
[Sine bars - 10 cycles]
The target image is inverted to burn the white bars (invisible on a white screen background) on either side at maximum power.
But grayscale mode comes with another gotcha: the power supply uses a 200-ish Hz lowpass filter to demodulate the PWM into the tube current value. A crisp “dot” image requires fairly st…
Definitely more than you really want to know …
