Patent ID: 7282697

Claim:
A vibration sensing device comprising a flexible disk having a first surface and a second surface, said first and second surfaces lying on either side of a radial plane; a mounting means arranged to mount the disk centrally and substantially symmetrically about said radial plane, such that a central portion of said first and said second surfaces of said disk are constrained from moving while the circumferential edge of said disk is free to move; a mass located on said disk substantially symmetrically about said radial plane such that the mass contacts only the outer circumferential edge of said disk, and extends toward the radially inner portion of the disk and exerts a force on said disk which is greater towards said circumferential edge of said disk than it is towards said central portion; an optical fibre mounted on said first surface of said disk, such that flexion of said disk produces a strain in said optical fibre which imposes a variation in at least one predetermined property of an optical signal transmitted through said optical fibre, said optical fibre being mounted such that at least one end is accessible for optical coupling to an optical device comprising a detector for detecting said changes in said at least one predetermined property of said transmitted optical signal.