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طراحی و ساخت نمونه اولیه شتاب سنج با قرائت به روش اپتیکی
غلام زاده، رضا Gholamzadeh, Reza
Design and Fabrication of a Prototype Accelerometer Based on Optical Readout
Gholamzadeh, Reza | 2025
80
Viewed
- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 58761 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Salarieh, Hassan; Akbari, Javad; Parsanasab, Gholam Mohammad
- Abstract:
- Optical accelerometers, due to their inherent immunity to electromagnetic interference, capability of reading extremely small displacements, and simplicity of the readout circuitry, have emerged as a serious alternative to conventional electronic accelerometers. In this dissertation, the design, improvement, and fabrication of multiple generations of optical accelerometers are investigated with the aim of achieving high sensitivity while enabling domestic fabrication and integration into inertial systems. In the first stage, an optical accelerometer based on the SU-8 polymer was designed and fabricated. Owing to its low mechanical mass, this version exhibited a high resonance frequency (3.7 kHz), a relatively wide bandwidth (2 kHz), and a measurement range of up to 50 g. Although its mechanical sensitivity was low (2 µm/g), the optimized optical design resulted in a final sensitivity of 1.4 %/g, which is higher than that of comparable designs. This outcome demonstrates that, in optical architectures, low mechanical sensitivity does not necessarily imply poor overall performance. In the second stage, by modifying the fabrication process and increasing the proof mass, an enhanced version was developed that preserved the advantages of the previous design while significantly reducing mechanical noise. This result indicates that performance optimization can be achieved through fabrication engineering without increasing the device dimensions. In the final stage, an optical accelerometer based on an SOI wafer was designed and fabricated. By exploiting the higher material density, the mechanical sensitivity increased to 600 µm/g and the final sensitivity reached 9.6 %/g, accompanied by a reduction in mechanical noise. Although the resonance frequency and bandwidth decreased compared to the initial version due to the increased mass, this design demonstrates one of the best performances among existing optical accelerometers in terms of sensitivity-to-size ratio. As a complementary step, an optical gyroscope was also designed and simulated to enable the development of a fully optical inertial measurement unit. The designed gyroscope, with a resonance frequency of 20 kHz and a sensitivity of 1.6 %/(°/s), is approximately three times more sensitive than similar reported devices and is capable of measuring angular velocities up to 50 °/s. These results demonstrate that by combining precise optical design, optimal material selection, and reconfiguration of the fabrication process, high-performance optical inertial sensors with small dimensions and domestic fabrication capability can be developed
- Keywords:
- Microring Resonator ; Microoptoomechanical Accelerometer ; Optical Accelerometer ; Direct-Write Fabrication
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