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Optical Direct Detection Of Thermal Vibrations Of Ultralow Stiffness Micro-Nano Structures., Sri Sukanta Chowdhury
Optical Direct Detection Of Thermal Vibrations Of Ultralow Stiffness Micro-Nano Structures., Sri Sukanta Chowdhury
Electronic Theses and Dissertations
A direct detection optical vibrometer is constructed around an 850 nm laser and a quadrant photodetector (QPD). The limit of detection is 0.2 fW which corresponds to a minimum amplitude of 0.1 Å. The vibrometer is used to measure the thermal vibration spectra of low stiffness micromechanical structures have nanometer features. One structure measured is a cantilevered 30 μm diameter glass fiber. Vibration amplitudes as low as 1.1 Å are measured. The thermal vibration spectra show fundamental resonances at 80-250 Hz and a signal to noise ratio (SNR) of 23-55 dB. Young’s modulus of glass in the cantilevers, estimated from …