# US 2018/0321085 A1 · Optical sensor system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321085 A1 - Document ID: US20180321085A1 - Status: Published application - Kind: A1 - Application number: 15/773,108 - Filed: 2016-11-07 - Published: 2018-11-08 - Earliest claimed: 2015-11-06 - Assignees: Optics11 B.V. - Applicants: Optics11 - Inventors: Grzegorz GRUCA; Niek RIJNVELD - Web page: https://patentgrep.com/patent/US20180321085A1 ## CPC - G01J 3/26: using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters - G01J 3/0218: {using optical fibers} - G01L 1/242: {the material being an optical fibre} - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract An optical sensor system includes an optical sensor arrangement that includes a Fabry-Perot structure having two reflective surfaces spaced apart at a distance from each other. A spectral acquisition arrangement acquires successive spectral responses from the optical sensor arrangement during successive time intervals. A spectral analysis arrangement detects a periodicity in at least one of the successive spectral responses that have been acquired. The spectral analysis arrangement further detects a phase evolution of the periodicity throughout the successive spectral responses. The phase evolution of the periodicity provides a relatively precise measurement of a variation in an optical path length between the two reflective surfaces of the Fabry-Perot structure. A variation in a physical quantity can cause the variation in the optical path length. Accordingly, a relatively precise measurement of the physical quantity can be achieved. ## Claims ### Claim 1 An optical sensor system (100) comprising: an optical sensor arrangement (101) comprising a Fabry-Perot structure (104) having two reflective surfaces spaced apart at a distance from each other, a spectral acquisition arrangement (102) coupled to optical sensor arrangement and adapted to acquire successive spectral responses from the optical sensor arrangement during successive time intervals, a spectral analysis arrangement (103) adapted to detect a periodicity in at least one of the successive spectral responses that have been acquired and to detect a phase evolution of the periodicity throughout the successive spectral responses. ### Claim 2 (depends on 1) An optical sensor system according to claim 1, wherein: the spectral analysis arrangement (103) is adapted to apply a transform of the time-to-frequency type to the successive spectral responses that have been acquired, so as to obtain, for a spectral response, an amplitude representation and a phase representation of the transform of the spectral response, the spectral analysis arrangement is adapted to identify a location where a peak occurs in an amplitude representation and to extract, from successive phase representations, local phase data at a location corresponding to the location where the peak occurs, so as to obtain a series of successive local phase data representing a local phase evolution in the successive phase representations. ### Claim 3 (depends on 2) An optical sensor system according to claim 2, wherein the transform of the time-to-frequency type comprises a Fourier transform. ### Claim 4 (depends on 2, 3) An optical sensor system according to any of claims 2 and 3, wherein the transform of the time-to-frequency type comprises a transform based on a Goertzel algorithm. ### Claim 5 (depends on 1, 2, 3, 4) An optical sensor system according to any of claims 1 to 4, wherein the spectral analysis arrangement (103) is adapted to detect a periodicity in a first spectral response of the successive spectral responses that have been required, and is adapted to update data on the periodicity on the basis of further successive spectral responses that follow. ### Claim 6 (depends on 1) An optical sensor system according to claim 1 comprising a plurality of Fabry-Perot structures, whereby respective Fabry-Perot structures have respective distances at which their two reflective surfaces are spaced apart, the spectral analysis arrangement (103) being adapted to detect respective periodicities in at least one of the successive spectral responses that have been acquired and to detect respective phase evolutions of the respective periodicities throughout the successive spectral responses. ### Claim 7 An optical sensing method that makes use of an optical sensor arrangement (101) comprising a Fabry-Perot structure (104) having two reflective surfaces spaced apart at a distance from each other, the optical sensing method comprising: a spectral acquisition step in which successive spectral responses are acquired from the optical sensor arrangement during successive time intervals, a spectral analysis step in which a periodicity is detected in at least one of the successive spectral responses that have been acquired, and in which a phase evolution of the periodicity throughout the successive spectral responses is detected. ### Claim 8 (depends on 7) A computer program product for an optical sensor system comprising an optical sensor arrangement (101) that includes a Fabry-Perot structure (104) having two reflective surfaces spaced apart at a distance from each other, the computer program product enabling a processor in the optical sensor system to carry out the optical sensing method according to claim 7.