Oscillation FPCB micromirror based triangulation laser rangefinder

Abstract

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 × 5.5 mm) and high flatness (radius of curvature, ∼ 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° to 10°, error ≤ 4%; with Laser 2, distance of 15–130 cm and FOV of −15° to 15°, error ≤ 5%; with Laser 3, distance 15–200 cm and FOV of −15° to (5 ∼ 9°), error ≤ 5%. Fatigue test indicates 0.8 billion scanning cycles have been reached.