| 摘要 |
A dual-mode resonant scanning system comprising an electronic control circuit and a dual-mode resonant mechanical scanner to produce an essentially triangular scan pattern. The dual-mode mechanical scanner is mechanically tuned to simultaneously oscillate at a predetermined fundamental frequency and a free running third harmonic thereof. The electronic control circuit drives the mechanical scanner to oscillate at the exact third harmonic of the predetermined fundamental frequency and phase locks the harmonic oscillation to the fundamental oscillation. The dual-mode resonant mechanical scanner includes an optical scanning element having a first mass, a second mass, at least one torsion rod, a rotational actuator and a mechanical ground designed and integrated together such that the mechanical scanner is self resonant at the predetermined fundamental frequency and at or within a few hertz of the exact third harmonic of the predetermined fundamental frequency. The electronic control circuit includes a mirror-position sensing subsystem, a bandpass filter tuned to the predetermined fundamental frequency, a multiplier circuit, a summing circuit, a manual phase and amplitude adjustment, a scan angle automatic gain control circuit and a driving circuit. The exact third harmonic oscillation in combination with the fundamental oscillation produces an essentially constant scan rate through a predetermined scan angle.
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