The measurement of absolute strain (or stress) in the small quarts crystal resonators by a single slit method - observation of vibratory character of a small NS-GT cut resonator

摘要

From the necessity of downsizing devices, the size of quarts crystal resonators has made smaller these days. If we make quarts crystal resonator's size smaller small external effects will change frequencies or quality factors of the resonator. And those changing make it more difficult to measure accurate stress distributions. In the vibrating diffraction of the single slit method, by making a single slit (or a pin point hale) and letting a laser beam into the slit, a diffraction pattern is changed a little bit. The diffraction pattern is dynamic but change itself is very small, therefore we need to detect the changes of diffractions using optical fibers. The searched optical signals are converted to the electric signal by a photomultiplier. The patterns of diffractions tell us the changes of a single slit width and the vibrating shift of the resonator. From those results, we can get the absolute values of strain (or stress) and the absolute vibrating shit value of the resonator. This time, I measured the internal strain and the vibrating shift value of a small NS-GT cuts by this method, experimentally. Knowing the absolute values, such as strains and vibrating shifts of a small quarts crystal is very useful to control the thickness of vacuum evaporation electrodes and improve mounting of resonators.