Fiber-optic pressure sensor, variants and method for producing a resilient membrane

Abstract

The inventions relate to measurements of a hydrostatic and/or fast-changing pressure by optical means, and are suitable for aerodynamic investigations of aircraft and small spacecraft, in robotics, including small force micro-clamps, in remote pressure monitoring (in wells, vessels, cylinders), in medicine and medical and biological investigations, hydroacoustics, security systems. The object is to improve the sensitivity and enhance the temperature and vibration stability of a pressure sensor. The pressure sensor is a low Q-factor Fabry-Perot cavity/interferometer at the end of a single-mode optical fiber with the 4% Fresnel reflection from the silica glass/air interface. Another movable mirror of the cavity is formed by an end face of a short (1-3 mm) optical fiber length having a small inertial mass and inserted into the center of a flexible membrane of 500-700 &mgr;m in diameter, tightly sealing a small air volume of about 1-3 mm inside a second capillary with the external diameter of 0.5 to 0.9 mm. End faces and of the optical fibers and forming the Fabry-Perot cavity with a gap of about 50 &mgr;m are placed inside the capillary with the internal diameter of about 145 &mgr;m. The temperature stability of the sensor is &Dgr;P/&Dgr;T≈0.001 atm/° C.