Self-oscillating FR4 laser scanner with integrated dynamic focus and extended imaging range

Abstract

A self-oscillating scanned beam imaging device is presented, with variable focusing mechanism and extended imaging range. The focusing and imaging optics, as well as the die level laser diode and photodiode are integrated on the same platform, and scanned synchronously to extend the imaging range of the system. More than 600mm imaging range is achieved with 52° total optical scan angle. An integrated back-emf coil both enables the self-starting of the oscillations of the scanner, and also provides the velocity feedback for running the system in closed-loop. A special circuit is implemented to decrease the time to reach 80% of the full amplitude self-oscillations from 970ms down to 60ms.