# US 2021/0333148 A1 · Measurement apparatus and measurement method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0333148 A1 - Document ID: US20210333148A1 - Status: Published application - Kind: A1 - Application number: 17/238,165 - Filed: 2021-04-22 - Published: 2021-10-28 - Earliest claimed: 2020-04-24 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Tomonori MATSUSHITA - Web page: https://patentgrep.com/patent/US20210333148A1 ## CPC - G01J 1/4257: {applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam (monitoring arrangements for lasers in general H01S3/0014)} - G01J 3/26: using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters - G01B 9/02004: using frequency scans - G01B 11/2441: {using interferometry} - G01J 1/0242: {Control or determination of height or angle information of sensors or receivers; Goniophotometry} - G01J 3/10: Arrangements of light sources specially adapted for spectrometry or colorimetry - G01B 2290/25: Fabry-Perot in interferometer, e.g. etalon, cavity - G01B 2290/35: Mechanical variable delay line - 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) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract A measurement apparatus includes a light source that emits light, a spectroscopic element that is configured to transmit light of a predetermined wavelength out of the light emitted from the light source portion, and capable of changing the predetermined wavelength of the light to be transmitted within a predetermined wavelength range, an interference optical system which separates light emitted from the spectroscopic element into measurement light irradiated on a measurement target and reference light reflected by a reference body, and generates interference light obtained by combining the measurement light reflected by the measurement target and the reference light reflected by the reference body, an image sensor that receives the interference light, and one or more processors configured to calculate a position of the measurement target based on spectrum information indicating a change in a received light quantity at the light receiving portion when the predetermined wavelength of the light transmitted through the spectroscopic element is changed. ## Claims ### Claim 1 A measurement apparatus comprising: a light source that emits light; a spectroscopic element that is configured to transmit light of a predetermined wavelength out of the light emitted from the light source portion, and capable of changing the predetermined wavelength of the light to be transmitted within a predetermined wavelength range; an interference optical system which separates light emitted from the spectroscopic element into measurement light irradiated on a measurement target and reference light reflected by a reference body, and generates interference light obtained by combining the measurement light reflected by the measurement target and the reference light reflected by the reference body; an image sensor that receives the interference light; and one or more processors configured to calculate a position of the measurement target based on spectrum information indicating a change in a received light quantity at the light receiving portion when the predetermined wavelength of the light transmitted through the spectroscopic element is changed. ### Claim 2 (depends on 1) The measurement apparatus according to claim 1, further comprising: an optical path length adjusting unit that adjusts an optical path length difference between the measurement light and the reference light, wherein the optical path length adjusting unit adjusts the optical path length difference such that a number of peak wavelengths included in the wavelength range of the spectrum information is minimized. ### Claim 3 (depends on 2) The measurement apparatus according to claim 2, wherein the optical path length adjusting unit changes an optical path length of the measurement light. ### Claim 4 (depends on 2) The measurement apparatus according to claim 2, wherein the optical path length adjusting unit changes an optical path length of the reference light. ### Claim 5 (depends on 2) The measurement apparatus according to any one of claim 2, wherein the light receiving portion has a plurality of pixels, and the optical path length adjusting unit changes the optical path length difference to a position where the received light quantity reaches a peak when one of a plurality of the pixels is set to a reference pixel and light of a predetermined reference wavelength is received at the reference pixel. ### Claim 6 A measurement method in a measurement apparatus including a light source that emits light, a spectroscopic element that is configured to transmit light of a predetermined wavelength out of the light emitted from the light source portion, and capable of changing the predetermined wavelength of the light to be transmitted within a predetermined wavelength range, an interference optical system which separates light emitted from the spectroscopic element into measurement light irradiated on a measurement target and reference light reflected by a reference body, and generates interference light obtained by combining the measurement light reflected by the measurement target and the reference light reflected by the reference body, and an image sensor that receives the interference light, the measurement method comprising: acquiring spectrum information indicating a change in a received light quantity at the light receiving portion when the predetermined wavelength of the light transmitted through the spectroscopic element is changed; and calculating a position of the measurement target based on the spectrum information.