Pockels cell modulation via look-up tables

The Scanbox card keeps the laser power per pixel constant across the imaging field despite variations in dwell time during the resonant scanning cycle.  It also blanks the laser entirely near the edges of each line.  The shape of the modulation signal is fully programmable, although each change requires a firmware update to the board. We achieve this by having a pixel counter for the line as an input to a look-up table which, in turn, drives a digital-to-analog converter.

We use a Conoptics system which accepts a 2Vp-p maximum modulation signal into a 1kOhm (unipolar) termination leading to 750Vp-p output modulation on the Pockels cell.  The oscilloscope snapshot below show the line synchronization of the resonant mirror controller along with the Pockels cell modulation during bidirectional scanning.






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