Fabry–Perot Interferometric Pressure Sensor With Thermally Stretched Ridged Metal Diaphragm for 0–1000-mbar Range

A method of achieving a pre-stressed pressure-sensitive diaphragm is discussed in this article. A design is developed, implemented, and demonstrated for a Fabry–Perot interferometer (FPI) based pressure sensor of range 0–1000 mbar. The diaphragm is designed as a ridged structure made of SS316L. It is thermally expanded and mounted on flange (sensor body). During cooling, diaphragm’s contraction gets ceased by the flange, resulting in pre-stressed diaphragm. The amount of pre-stress is governed by the diametric deficit between the diaphragm and the flange. The developed sensor is tested using white light interferometry (WLI) scheme and the experimental results are compared with the finite-element analysis (FEA) results. The repeatability and accuracy are found to be 1.22% and 1.56% of full scale, respectively. To the best of our knowledge, such design and method of achieving pre-stressed diaphragm in FPI pressure sensor is reported for the first time.