An external electromagnet plus moving PM (permanent magnet) FPCB (flexible printed circuit board) micromirror is proposed in this paper that can overcome two limitations associated with the previous FPCB micromirror with a configuration of an external PM plus moving coil, i.e., (1) it reduces the overall width beyond the mirror plate, and (2) increases the maximum rotation angle. The micromirror has two external electromagnets underneath an FPCB structure (two torsion beams and a middle seat) with two moving PM discs attached to the back and a metal-coated mirror plate bonded to the front of the FPCB middle seat. Modeling and simulation were introduced, and the prototype was fabricated and tested to verify the design. The achieved performance was better than that of the previous design: a maximum resonant rotation angle of 62° (optical) at a driving voltage of ±3 V with a frequency of 191 Hz, the required extra width beyond the mirror plate was 6 mm, and an aperture of 8 mm × 5.5 mm with a roughness of <10 nm and a flatness of >10 m (ROC, radius of curvature). The previous FPCB micromirror’s performance was: strain limited maximum rotation angle was 40° (optical), the extra width beyond the mirror plate was 14.7 mm, and had an aperture of 4 mm × 4 mm with a similar roughness and flatness.
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.
<p>This thesis presents an electromagnetic FPCB (Flexible Printed Circuit Board) micromirror based scanning triangulation laser rangefinder (LRF). Two configuration designs of the electromagnetic FPCB micromirror have been developed and tested. The FPCB micromirror has a large aperture (8 mm x 5.5 mm) and high flatness (ROC, radius of curvature, ~ 15m), that overcomes conventional MEMS micromirrors’ limitation of small aperture (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 thesis 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 FOV, field of view) 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 1.2 billion scanning cycles have been reached.</p>
<p>This thesis presents an electromagnetic FPCB (Flexible Printed Circuit Board) micromirror based scanning triangulation laser rangefinder (LRF). Two configuration designs of the electromagnetic FPCB micromirror have been developed and tested. The FPCB micromirror has a large aperture (8 mm x 5.5 mm) and high flatness (ROC, radius of curvature, ~ 15m), that overcomes conventional MEMS micromirrors’ limitation of small aperture (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 thesis 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 FOV, field of view) 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 1.2 billion scanning cycles have been reached.</p>
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