Abstract
This study proposes a miniature and highly sensitive Fabry-Perot interferometer (FPI) based on aluminum - polyimide diaphragm integrated with a mass block for acceleration sensing. The composite diaphragms with a radius and thickness of 3.5 mm and 630 nm are manufactured by Micro-Electro-Mechanical System (MEMS) technology. To increase the adhesion of the polyimide diaphragm to silicon wafer and improve the quality of deflectable diaphragm, a 30-nm-thick aluminum diaphragm is first coated on the silicon wafer by magnetron sputtering; a silicon wafer in the intermediate diaphragm is reserved as a mass block to form an integrated structure. Air cavity of the FPI formed by this composite diaphragm is modulated via external vibration signals, leading to a variation in the length of the cavity. Three fiber optic Fabry–Perot accelerometers (FOFPAs) are fabricated with a measured average sensitivity and acceleration resolution of 2.6 V/g (100 Hz–3.2 kHz) and $4.12~\mu \text{g}$ /Hz $^{\mathrm {1/2}}$ respectively, which show high consistency and manufacturing reproducibility. Good heat resistance performance of the sensor below 280° can also be observed obviously. Thus, this proposed sensor is anticipated to have wide application prospects in micro vibration monitoring in high temperature.
Highlights
Fiber optic accelerometer (FOA) has led to remarkable developments during recent years, with its unique advantages [1]–[3], such as a low cost, immunity to electromagnetic interference, light weight, and small size compared with conventional electrical acceleration sensors
According to its mechanical structure, FOA can be divided into three types: cantilever structure [7]–[9], mandrel structure [10], [11], and diaphragm structure [12]; in particular, fiber optic Fabry– Perot accelerometers (FOFPAs) based on a deflectable
Li et al.: Fabry-Perot interferometer (FPI) Based on an Aluminum-Polyimide Composite Diaphragm Integrated With Mass for Acceleration Sensing a Fabry–Perot cavity, which is formed by placing the end face of a gradient-index lens in parallel with an inertial mass, with the resonant frequency and resolution of 393 Hz and 450 μg/Hz1/2
Summary
Fiber optic accelerometer (FOA) has led to remarkable developments during recent years, with its unique advantages [1]–[3], such as a low cost, immunity to electromagnetic interference, light weight, and small size compared with conventional electrical acceleration sensors. S. Li et al.: FPI Based on an Aluminum-Polyimide Composite Diaphragm Integrated With Mass for Acceleration Sensing a Fabry–Perot cavity, which is formed by placing the end face of a gradient-index lens in parallel with an inertial mass, with the resonant frequency and resolution of 393 Hz and 450 μg/Hz1/2. Li et al [16] reported a fiber optic extrinsic Fabry–Perot accelerometer on a polyethylene diaphragm with a diameter of 10.0 mm and an acceleration resolution of 24.4 μg/Hz1/2 over a frequency bandwidth of 20 Hz–1.5 kHz. to the best of our knowledge, FOFPAs with smaller size, higher sensitivity, and wider frequency band will have more future application prospects in the field of vibration detection in high temperature. Three acceleration sensors with same size are fabricated and evaluated, achieving excellent performance
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