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Characteristc of Quartz Crystal |
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| Quartz is the standard for frequencies |
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 Quartz has a high Q value. To draw an example from Buddhist temple bells, the Q value is the duration of the reverberation of the bell. If you strike the bell once, the reverberation continues for a long time: the longer the duration of this vibration, the higher the Q value. Quartz has a high Q value --- several million --- and has the property of emitting a given frequency, stably.
Quartz crystal units only vibrate when connected to an electrical circuit.
Tuning fork oscillators for clocks work on the same principle as the tuning fork used to tune a guitar. A tuning fork is made to vibrate by tapping it on something. Tuning fork oscillators are made to vibrate by giving them an electric shock.
If a stable frequency is required, the quartz crystal unit and the electronic circuit are placed together in a constant temperature oven, which keeps the temperature at a set level. With this type of temperature control, quartz crystal oscillators play a key role in a wide range of basic infrastructure, being used in broadcasting station and base station equipment for wireless communications, as standards for measuring instruments.
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| Optical characteristics of quartz |
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Quartz is transparent over a wide range of wavelengths from ultraviolet to infrared. It also has the property that its refraction index and coefficient of linear expansion change very little with temperature.
Taking advantage of these properties, quartz is widely used as an optical material in birefringent plates, wavelength plates and rotation plate, etc.
Birefringent plates (optical low-pass filters) are typically used to prevent moire in digital still cameras and video cameras, while wavelength plates are used to modify the polarization and enhance the efficiency with which optical engines use light in optical pickups and projectors. Quartz also offers outstanding laser resistance and for this reason is used in a wide range of industrial equipment.
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