Patent ID: 7832276

Claim:
A device to measure a fluid pressure comprises a pressure sensing element and a pressure readout element, wherein: the pressure sensing element comprises a cavity capped by a flexible membrane, the cavity having a length (d) that varies with the fluid pressure (P 1 ) applied on the flexible membrane, and the pressure readout element comprises a light source for providing an incident beam of a determined wavelength range directed towards the cavity and an optical spectral analyzer for measuring a power spectrum of a return beam reflected by the cavity, and processing means for determining the cavity length (d) and the fluid pressure (P 1 ) based on the power spectrum, wherein the pressure readout element further comprises a fiber optic collimator accommodated in the hole behind the reference window, the fiber optic collimator being coupled to the light source and the optical spectral analyzer through an optical fibre and an optical coupler, the optical spectral analyzer being coupled to the processing means.