In-line laser scanning unit with multiple light beams

An in-line laser scanning unit (LSU) with multiple light beams comprising a semiconductor laser set, a collimator lens set, a micro electronic mechanic system (MEMS) oscillatory mirror set, and a F-sin θ linear scanning lens set;

• the semiconductor laser set emits a plurality of laser beams and respectively emitted onto the collimator lens set;
• the collimator lens set receives laser beams from the semiconductor laser set and form parallel light beams respectively being emitted to the MEMS oscillatory mirror set;
• axis of each laser beam corresponds to oscillatory axis of the MEMS oscillatory mirror set;
• the micro electronic mechanic system (MEMS) oscillatory mirror set having a plurality of MEMS oscillatory mirror that stacked vertically into a MEMS array structure;
• by the MEMS oscillatory structure oscillating in harmonic motion at regular oscillating amplitude, the incident laser beams are reflected from each oscillatory mirror onto the F-sin θ linear scanning lens set;
• and
• the F-sin θ linear scanning lens set having a plurality of F-sin θ lens stacked into an array structure and each of the F-sin θ lens corresponds to a laser beam being reflected by the MEMS oscillatory mirror;
• the F-sin θ lens corrects the variation of reflective angle sinusoidal in time of the MEMS oscillatory mirror so as to make the scanning speed of laser beam on the image plane to be constant;
• thereby a plurality of laser beams emitted from the semiconductor laser set respectively passes through the collimator lens to form parallel beams, each of which is emitted to the MEMS oscillatory mirror;
• then each of the laser beams is reflected onto the F-sin θ lens by the oscillatory mirror oscillating in harmonic motion at regular oscillating amplitude;
• the F-sin θ lens corrects the variation of reflective angle of the MEMS harmonic moved oscillatory mirror that is sinusoidal in time as to make the scanning speed of multiple laser beams on the image plane to be constant for achieving requirement of scanning linearity.