Oscillation FPCB micromirror based triangulation laser rangefinder

摘要

This paper reports an electromagnetic oscillation flexible printed circuit board (FPCB) micromirror based scanning triangulation laser rangefinder (LRF). The FPCB micromirror has a large aperture (8 mm x 5.5 mm) and high flatness (radius of curvature, similar to 15 m), that overcomes conventional MEMS micromirrors' limitation of a small aperture size (less than 5 mm). Subsequently high power lasers with large beam sizes and good collimation can be used in micromirror based scanning LRF for better performance. As a result, the LRF in this paper achieved a larger scanning angle and longer detecting distance than those in literature. Both modelling and prototyping are presented. Three lasers (Laser 1: 2 mW; Laser 2: 20 mW; and Laser 3: 100 mW) are used to characterise the LRF. Eye-safety calculation is presented for the three lasers. Achieved performance (measurement distance and field of view (FOV)) is: with Laser 1, distance of 15-70 cm and FOV of -15 degrees to 10 degrees, error <= 4%; with Laser 2, distance of 15-130 cm and FOV of -15 degrees to 15 degrees, error <= 5%; with Laser 3, distance 15-200 cm and FOV of -15 degrees to (5 similar to 9 degrees), error <= 5%. Fatigue test indicates 0.8 billion scanning cycles have been reached.