Displacement and strain measurement up to 1000 °C using a hollow coaxial cable Fabry-Perot resonator

A hollow coaxial cable Fabry-Perot resonator for displacement and strain measurement up to 1000 °C is presented here. Inspired by optical fiber Fabry-Perot interferometers, a Fabry-Perot resonator is implemented on a homemade hollow coaxial cable by introducing two highly-reflective reflectors along the cable. By tracking the shift of the amplitude reflection spectrum of the microwave resonator, the displacement and strain can be determined. The displacement measurement experiment showed the sensor could function properly up to 1000 °C. The sensor was also employed to measure the thermal strain of a steel plate during the heating process from 100 to 900 °C.