Fabry–Perot Interferometer Used to Measure Very Low Static Pressure Measurements

Abstract

This paper describes the use of an optical instrument, the Fabry–Perot interferometer, adapted to measure very low pressures. The interferometer consists of two high-reflectance flat mirrors placed one in front of another. In addition, a metallic chamber contains air or a gas. In one of the faces of the chamber, a flexible thin silicone membrane is attached and, over it, one of the mirrors is glued. The other mirror rests in a fixed mechanical mounting. Light crosses both mirrors and, when it leaves them, forms an interference pattern consisting of concentric circular fringes. When the pressure is increased/decreased within the chamber, a displacement of the fringes is observed due to the movement of the glued mirror. By measuring the fringe displacement and knowing the pressure, a calibration plot can be made. Minimum pressure measurements of about tens of Pascals were achieved.

Keywords

• sensor devices
• pressure sensor
• physical sensor
• optical sensor
• Fabry–Perot interferometer
• polydimethyl siloxane