A novel digitally-actuated shaped micromirror for on-off optical switch applications is described. Reflective static spherical mirrors were designed and fabricated using conventional surface micromachining and the MultiPoly process, a technique for depositing multilayers of LPCVD polysilicon in order to control the overall stress and stress gradient. The resulting mirrors were measured to have radii of curvature of approximately 9 mm in agreement with design predictions. Based upon these static mirrors, an actuatable micromirror (diameter = 500 m, static radius of curvature = 6 4 mm) was designed for snap action. This mirror was simulated using an electromechanical coupled-field model and fabricated using the MultiPoly process. Its performance was measured dynamically using an interferometer. A curved-to-flat digital actuation of the mirror was successfully achieved with a pull-in voltage of 38 V.[1211]Index Terms-Curvature modulation, microelectromechanical systems (MEMS), micromirror, multilayer, optical switch.
This paper presents a tri-axis MEMS gyroscope design with novel tetra-pendulum proof masses for X-, Y-axis and regular proof masses for Z-axis rate sensing, which are all coupled with and embedded in a conventional tuning fork driving frame. The four pendulum proof masses are suspended via the torsional springs to a common center anchor and can be driven to swing around the anchor via the tilted transforming springs as the driving frame is oscillated in an anti-phase mode. As an X-, Y-axis angular rate is applied, the tetra-pendulum proof masses will rotate around the torsional springs in pairs for X- and Y-axis differential sensing, respectively. In particular, we investigated the relationship between the tilting angle of the transforming spring and its transforming efficiency, i.e. the amplitude ratio of the pendulum's swing to the driving oscillation, which shows a straight impact on the sensitivity. By theoretical analysis and Ansys simulation, we achieved an optimal tilting angle of 22.5°, which extends along the angular bisector of the pendulum's and driving mass’ moving direction and demonstrates a significant increase in transforming efficiency by about 40%, compared with the trivial tilting angle of 45°. By employing an SOI-based bulk micromachining process, the prototype device with the optimal design of the transforming spring (type I) and that with the trivial design (type II) for reference have been successfully fabricated. As expected, the testing results indicate an increase of more than 20% in the X- and Y- sensitivities, which is mainly from the enhanced sensitive transforming springs.
Integrated optical rotation sensor(IORS) is a new type of optical sensors. In this paper, an integrated acoustooplic frequency shifter (AOFS) with surface acoustic wave (SAW) is developed as one of key integrated elements of IORS. The design, fabrication and test of acoustooptic frequency shifter with SAW are presented. The wedge of zinc oxide film on glass substrate is designed as new structure for using in JORS. Experimental results show that the performance of zinc oxide film is stable, the linearity of zinc oxide wedge is suitable for improving Bragg diffraction efficiency. and some good mono-mode performances of planar waveguide are obtained. The frequency shift of 198MHz±O.75MHz, diffraction efficiency of 8% (at optical wavelength of O.63m). and 3-5% (at optical wavelength of 1.O6m) are obtained at I Watt of electrical power. These experimental results satisfy the main requirements of IORS. High frequency stability is the main specification of RF driving circuits for using SAW AOFS in IORS. In this paper, a new digital scheme based on direct digital synthesis is presented for improving frequency stability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.