8 September 2011 Design of a MOEMS-based electromagnetic driven high efficacious phase grating with angle sensor
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A novel design for fabricating the high efficacious rectangular phase grating with angle sensor by MOEMS fabrication process is presented in this paper. The purpose of this design is for increasing the Signal-to-Noise of output signal and reducing the size of near infrared spectrometer by using MOEMS grating. Diffraction efficiency is designed and optimizing at first. We used Fourier optical theory and diffraction optical theory analyzed the diffraction efficiency of the rectangular phase grating, and used the PCgrate simulated the design. After analysis and calculation, we found the best parameter of this grating. According the former design of infrared spectrometer by ZEMAX, the angle resolution of angle sensor is 60mV/°, maximal angle is ±4.7° and the size of grating is 5x6mm2. Because of the large deflection angle, the electromagnetic force is used for driving this grating. For sensing the grating deflexion angle, we design the angle sensor in the torsion bar of this grating. This sensor is P-type piezoresistive sensor and fabricated on n-(100) high-resistance silicon wafer by boron ion implantation. Analyses stress of torsion bar and piezoresistive angle sensor with Wheatstone bridge theory, the scanning angle θ in a linear relation with output voltages (Vout) of Wheatstone bridge. The size of torsion bar is 2100μmx220μmx75μm, the frequency of first step model is 550Hz. The size of the sensor is 100μmx15μmx0.5μm. Finally, the compatible fabrication process of this device is given. The results of experiments and theory analyzing demonstrate that MOEMS phase grating could work effectively, and angle sensor achieve the real time need. This MOEMS grating is suitable for infrared spectrometer.
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Biao Luo, Biao Luo, Zhi Yu Wen, Zhi Yu Wen, Li Chen, Li Chen, } "Design of a MOEMS-based electromagnetic driven high efficacious phase grating with angle sensor", Proc. SPIE 8191, International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies, 819122 (8 September 2011); doi: 10.1117/12.900955; https://doi.org/10.1117/12.900955

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