![]() ![]() Next we study the possibility to replace the PSD sensor with an embedded capacitive phase-angle sensor. Using an external position sensitive device (PSD) the proper working of the PLL is demonstrated. The design is based upon a thorough understanding of the (non-linear) dynamical behavior of the mirror. Keywords: MEMS micromirror laser display raster scanning, capacitive tilt-angle sensor PLLĪB - This paper describes the design and realization of an electrostatic actuated MEMS mirror operating at a resonance frequency of 23.5 KHz with a PLL feedback loop. This demonstrates the feasibility of a fully embedded control for a resonant scanning MEMS mirror. We show measurements of capacitance changes with large parasitic influences while actuating the mirror in a feed forward mode. N2 - This paper describes the design and realization of an electrostatic actuated MEMS mirror operating at a resonance frequency of 23.5 KHz with a PLL feedback loop. Proceedings of the Eurosensors XXIII conference Hosako, “Active THz imaging using MEMS resonator-based bolometer and quantum cascade laser,” th International Conference on Infrared, Millimeter, and Terahertz Waves, We-POS-35 (2018).T1 - Towards embedded control for resonant scanning MEMS micromirror Hirakawa, “Fast and sensitive bolometric terahertz detection at room temperature through thermomechanical transduction,” J. Hirakawa, “Effect of buckling on the thermal response of microelectromechanical beam resonators,” Appl. Hirakawa, “Room temperature, very sensitive thermometer using a doubly clamped microelectromechanical beam resonator for bolometer applications,” Appl. Sasaki, “Microbolometer terahertz focal plane array and camera with improved sensitivity in the sub-terahertz region,” J. Enz, “A low-noise CMOS THz imager based on source modulation and an in-pixel high-Q passive switched-capacitor N-path filter,” Sensors 16, 325 (2016). “Active terahertz imaging using Schottky diodes in CMOS: array and 860-GHz pixel,” IEEE J. Ishibashi, “Low noise homodyne detection of terahertz waves by zero-biased InP/InGaAs Fermi-level managed barrier diode,” IEICE Electron. Ishibashi, “InP/InGaAs Fermi-level managed barrier diode for broadband and low-noise terahertz-wave detection,” Jpn. Mittleman, “Twenty years of terahertz imaging,” Opt. Davies, “Terahertz imaging using quantum cascade lasers – a review of system and applications,” J. Tonouchi, "Cutting-edge terahertz technology," Nat. In the case of the PED, the resolution gradually degraded with increasing stage speed. When the images were acquired using the MEMS bolometer with a stage speed of 25 mm/s, fine structures of a metal bookmark were clearly observed and no degradation in the resolution was observed with changing stage speed. For the PED, there was a decrease in the peak intensity and delay in the peak positions with increasing stage speed due to the insufficient response speed. In the measurement of the response characteristics using a 100-μm pinhole, the peak intensity was almost constant against the stage speed in the case of the MEMS bolometer. The frequency shifts in the resonant peak due to the irradiation of the THz waves were tracked using the phase-locked loop system built in the lock-in amplifier. The MEMS bolometer had a beam resonator with a resonant peak of 422 kHz, and it was operated in the frequency modulation detection mode. The scanning process of the imaging system consisted of continuous scans in the X direction and step scans in the Z direction. The imaging system was an active imaging composed of the MEMS bolometer, THz quantum cascade laser, and two-dimensional translation stage. The impact of the response speed of a microelectromechanical system (MEMS) bolometer on the quality of terahertz (THz) imaging with rapid scan has been investigated and compared with a pyroelectric detector (PED). ![]()
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