Patent ID: 6567173
Filing Date: 2003-05-20
Classification: A61B,G01L

Abstract:
Optical pressure sensor comprising an optical fibre (1) having a well defined end part (1A) and a casing (3) having a cylindrically shaped cavity with essentially the same diameter as the optical fibre (1), the end (1A) of the optical fibre being positioned at a chosen axial position inside the cavity thus to close one end of the cavity, characterized in a body (2) positioned in the cavity having a first at least partially reflective surface (2A), said partially reflective surface (2A), fibre (1) and casing (3) defining a chamber (5), said chamber containing a compressible fluid, said chamber (5) being at least partially sealed by a liquid (4), and whereby the position of said partially reflecting surface (2A) depends on the hydrostatic pressure within the chamber (5), and where at least one of said body (2) and the optical fibre (1) being movably connected to the casing in the axial direction in that at least a part of the said liquid (4) forms a lubricating layer in the connection with said casing (3) by at least partially filling the space (2B) between the body (2) and the casing (3), thus to provide a pressure coupling between the chamber (5) and the environment.