A translation micromirror with large quasi-static displacement and high surface quality

Abstract

A large displacement with high surface quality translation micromirror is presented. The micromirror consists of a magnetic actuator and a mirror plate. The actuator and the mirror plate are fabricated separately using two processes and then bonded together. The actuator consists of a moving film which is a 20 µm thick nickel film fabricated by MetalMUMPs and a solenoid located underneath the moving film. The moving film is designed to curve up through the residual stress gradient in the nickel film and a curve-up mechanism which includes four trapezoidal plates and anchoring springs. The mirror plate is simply diced from a polished silicon wafer and coated with a metal thin film. The mirror plate is bonded onto the central ring of the moving film. A solenoid attracts the moving film along with the mirror plate downwards to realize translation. A quasi-static displacement of 123 µm is achieved at a driving current of 400 mA. A high mirror surface quality is realized, e.g. 15.6 m of curvature radius and 2 nm surface roughness.

A tilt compensation system for translation micromirror

“…By comparing with other compensating systems, it has smaller size, simpler structure, and lower cost. The proposed tilting compensation technology can be used not only for the translation micromirror developed by our group 6 but also for other translation micromirrors as long as the micromirror's tilting is about one fixed axis. The compensation micromirror rotates the angle of the same magnitude and same direction of the translation micromirror's tilt.…”

“…The compensation micromirror rotates the angle of the same magnitude and same direction of the translation micromirror's tilt. In the experiment, a translation micromirror, 6 a 1D Lorenz force magnetic rotation micromirror, 36 and a reflecting mirror form the compensation system. And its performance in a Michelson interferometer is tested.…”

“…The tilt can be caused by multiple reasons, for example, the fabrication process variation leads to discrepancies between actuators; 16 and the manufacturing/ assembly error lead to the uneven magnetic fields applied to micromirror's symmetric part. 6,8 Since those undesired tilt causes are normally constant/unchanged during the translation of the mirror, the tilt is normally about a fixed axis. This article proposes a tilt compensation system to compensate for the translation micromirror's tilt, which is about a fixed axis.…”

Development of an Electromagnetic Actuator based Translation Micromirror as a Movable Mirror in a Miniaturized FTIR Spectrometer

“…The magnetic actuator takes advantage of the magnetic field to generate force or torque to drive the micromirror. Lorentz force [78]- [89] and magnetostatic force [90]- [114] based magnetic actuators are most common. Lorentz force actuator is based on the interaction between the current carrying conductor and the external magnetic field, as shown in Figure 1.14a.…”

Review of MEMS Based Fourier Transform Spectrometers

“…The mirror achieved a high surface quality with 15.6 nm curvature radius and 2 nm surface roughness. Xue et al introduced a large displacement with high surface quality in-plane electromagnetically actuated translation micromirror for FTS in 2016 [46]. The actuator comprised a nickel film (see Figure 23a) fabricated by MetalMUMPs [47], and a solenoid located underneath the film.…”