A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain. The structure works only in resonant mode without requiring any offset in the comb fingers, keeping the silicon-on-insulator-based process quite simple. The design intent is to improve actuator efficiency by removing the high-drag fingers from the high-velocity scanning mirror. Placing them on the lower velocity drive frame reduces their contribution to the damping torque. Furthermore, placement on the drive frame allows an increase of the number of fingers and their capacity to impart torque. The microscanner exhibits a parametric response, and as such, the maximum deflection is found when actuated at twice its natural frequency. Analytical formulas are given for the coupled-mode equations and frame deflections. A simple formula is derived for the mechanical-gain factor. For a 1-mm × 1.5-mm oblong scanning mirror, a 76 • total optical scan angle is achieved at 21.8 kHz with 196-V peak-to-peak excitation voltages.[2009-0304]
This paper presents a new method for the CMOS compatible fabrication of microchannels integrated into a silicon substrate. In a single-step DRIE process (Deep Reactive Ion Etching) a network of microchannels with High Aspect Ratio (HAR) up to 10, can be etched in a silicon substrate through a mesh mask. In the same single etching step, multidimensional microchannels with various dimensions (width, length, and depth) can be obtained by tuning the process and design parameters. These fully embedded structures enable further wafer processing and integration of electronic components like sensors and actuators in wafers with microchannels.
625 nm thick a-Si layer was crystallized by using microsecond pulsed green laser with wavelength of 515 nm. At least 8 μm size grains were formed using location controlled single grain technique at room temperature. Energy density window for crystallization and ablation were compared for pulse durations of 300 ns, 1000 ns and 1200 ns.
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