About the quartz thermometers
The quartz thermometer makes use of the principle that the resonant frequency of a material such as quartz is a function of temperature, thus enabling temperature changes to be translated into frequency changes. The temperature-sensing element consists of a quartz crystal enclosed within a probe (sheath). The crystal is connected electrically so as to form the resonant element within an electronic oscillator. Measurement of the oscillator frequency therefore allows the measured temperature to be calculated.