Development of a Miniature Two-Dimensional Optical Scanner. 1st Report. Scanning Principle and Fundamental Performances.

Abstract

A new miniature two-dimensional optical scanner is proposed as part of the work to reduce the size of conventional scanners and to realize two-dimensional optical scanning of a large area. The proposed miniature optical scanner is composed of a small two-dimensional resonator made of a single-crystal silicon plate 0.2 mm thick and a 5 mm×5 mm×10 mm multilayer piezoelectric actuator to excite the resonator; the size of the external form is 15 mm×15 mm×10 mm. The resonator can vibrate in two orthogonal directions due to the bending and torsional vibrations of a small plate spring which supports the resonator, and can then reflect a laser beam two-dimensionally onto a mirror surface which is fabricated on the resonator. The natural frequencies of bending and torsional vibrations are greatly different from each other, namelys 288 Hz and 121Hz, respectively, and the Q-values of those vibrations are also very high, about 200 and 150, respectively. The horizontal, vertical or two-dimensional directions of the optical scan can thereby be easily switched by selecting and controlling the driving frequency of the piezoelectric actuator, and a large optical scanning area, 10 degrees and 16 degrees in horizontal and vertical directions, respectively, is obtained.