Application of the photo-elastic method to measurement of dynamic stress distribution for NS-GT cut quartz crystal resonators
NS-GT cut quartz crystal resonators are widely used as a frequency standard element in consumer products and communication equipment. The vibration mode of the resonators was analyzed by the finite element method (FEM) because they have a complicated shape. As a result, an asymmetrical vibration mode at the main resonant frequency has been obtained by the FEM simulation. But, it is necessary to confirm the asymmetrical vibration mode experimentally because it is just a simulation. In this paper, stress distributions of the NS-GT cut quartz crystal resonators are measured experimentally by using a dynamic photo-elastic method when the resonators are vibrating in the resonant frequency; thereafter, vibration modes of the NS-GT cut resonators are estimated with the experimental data of the stress distributions. This experiment for the NS-GT cut quartz crystal resonators exposes the existence of a twisted asymmetrical vibration mode at the main resonant frequency, with the magnitude of the twisted vibration in proportion to thickness of the resonators.
New Frequency Temperature Characteristics of Miniaturized GT-Cut Quartz Resonators
Summary This paper describes the shape, size and frequency-temperature characteristics c.f a miniaturized GT cut quartz resonator. We have developed a ne.w GT cut quartz resonator, which is greatly miniaturized, highly shock resistant and has excellent frequency-temperature characteristics cver a wide temperature range. In order to obtain sufficient processing accuracy, this quartz resonator is u.anufactured by a lithographic process, and, by means of a one-body formation of a vibrational portion and supporting portions of the quartz resonator, it can be made small. To describe it in still more detail, in order to minimize the energy losses caused by vibrations of the supporting portions, the quartz resonator has been designed such that the amplitude of vibrations, derived from the vibrational portion and transmitted to the supporting portions, which have the function of changing the length-extensioral vibration derived from the vibrational. portion into a flexural mode vibration, is minimized at the end of the sc.pporting portions and thus there is h.ardly any distortion.
Defects in Synthetic Quartz
The defects in hydrothermally grown synthetic quartz have been studied by x‐ray diffraction topography. Linear defects which are apparently associated with the growth of the crystal are the predominant defects in z‐growth material. These defects which originate at inclusions or other defect sites on the seed surface are believed to be areas of high impurity content. If there are dislocations associated with the defects, their effect on the diffracted x‐ray intensity is affected by a surrounding cloud of impurity atoms. Defect densities range from 10 to 104 lines per square cm and the crystals with high densities of defects exhibit high acoustic loss at 5 Mc/sec and 300°K. The defects observed in synthetic quartz by etch, γ‐ray coloration, and polarized light are compared to those observed by x‐ray diffraction topography.