# US 2014/0152993 A1 · Interferometer and spectrometer including same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152993 A1 - Document ID: US20140152993A1 - Status: Published application - Kind: A1 - Application number: 14/131,828 - Filed: 2012-06-14 - Published: 2014-06-05 - Earliest claimed: 2011-07-13 - Assignees: Konica Minolta, Inc. - Inventors: Yusuke Hirao - Web page: https://patentgrep.com/patent/US20140152993A1 ## CPC - G01J 3/4532: {Devices of compact or symmetric construction (G01J3/4531 takes precedence)} - G01J 3/027: {Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation} - G01J 3/0289: {Field-of-view determination; Aiming or pointing of a spectrometer; Adjusting alignment; Encoding angular position; Size of measurement area; Position tracking} - G01J 3/45: Interferometric spectrometry - G01J 3/4535: {Devices with moving mirror (G01J3/4532 takes precedence)} - G01J 9/02: by interferometric methods (using interferometers for measuring optically the linear dimensions of objects G01B9/02) - 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) ## Abstract An optical path of measurement light emitted from a measurement light source is overlaid by a beam combiner on an optical path of reference light emitted from a reference light source. The measurement light emitted from the measurement light source includes light in the sensitivity wavelength range (S1) of a measurement light detector and light in the sensitivity wavelength range (S2) of a reference light detector. An interferometer includes a wavelength separation filter that cuts light in at least a part of the sensitivity wavelength range (S2) of the reference light detector, of light included in the wavelength range of the measurement light. ## Claims ### Claim 1 An interferometer comprising: a measurement light source that emits measurement light; a measurement light detector that detects the measurement light; a reference light source that emits, as reference light, laser light whose wavelength is shorter than a sensitivity wavelength range of the measurement light detector; a reference light detector that detects the reference light; a beam combiner that overlays an optical path of the measurement light and an optical path of the reference light; a first beam splitter that separates, into two light beams, each of the measurement light and the reference light entering through the beam combiner; a first reflective member that is arranged on an optical path of one of the two light beams separated by the first beam splitter and that reflects and makes each of the measurement light and the reference light enter the first beam splitter again; a second reflective member that is arranged on an optical path of the other of the two light beams separated by the first beam splitter and that reflects and makes each of the measurement light and the reference light enter the first beam splitter again; and a second beam splitter that separates, into two light beams, light which is subjected to interference in the first beam splitter and emitted by the first beam splitter, and that guides the light beams to the measurement light detector and the reference light detector, respectively, wherein, based on a result of detection by the reference light detector when the first reflective member and the second reflective member are relatively moved, the interferometer measures the measurement light while detecting an optical path difference of the two light beams separated by the first beam splitter, the measurement light emitted from the measurement light source includes light in a sensitivity wavelength range of the measurement light detector and light in a sensitivity wavelength range of the reference light detector and the interferometer further includes a wavelength separation filter that cuts light in at least a part of the sensitivity wavelength range of the reference light detector, of light included in a wavelength range of the measurement light. ### Claim 2 (depends on 1) The interferometer of claim 1, wherein the wavelength separation filter cuts, of the light included in the wavelength range of the measurement light, light in a range that is within the sensitivity wavelength range of the reference light detector and that is separate from a wavelength range which includes the wavelength of the laser light and which is narrower than the sensitivity wavelength range. ### Claim 3 (depends on 2) The interferometer of claim 2, wherein the wavelength separation filter is arranged in an optical path between the second beam splitter and the reference light detector. ### Claim 4 (depends on 3) The interferometer of claim 3, wherein the wavelength separation filter transmits light in the wavelength range including the wavelength of the laser light, within the sensitivity wavelength range of the reference light detector, of the light entering from the second beam splitter. ### Claim 5 (depends on 1) The interferometer of claim 1, wherein the wavelength separation filter is formed with: a first optical filter that is arranged in an optical path between the measurement light source and the beam combiner; and a second optical filter that is arranged in an optical path between the second beam splitter and the reference light detector, the first optical filter cuts light in a part of the sensitivity wavelength range of the reference light detector including the wavelength of the laser light, of the light included in the wavelength range of the measurement light and the second optical filter cuts remaining light in the sensitivity wavelength range of the reference light detector, of the light included in the wavelength range of the measurement light. ### Claim 6 (depends on 5) The interferometer of claim 5, wherein the first optical filter cuts, of the light included in the wavelength range of the measurement light, light from a wavelength shorter than a shortest wavelength in the sensitivity wavelength range of the reference light detector to a wavelength longer than the wavelength of the laser light but shorter than a longest wavelength in the sensitivity wavelength range of the reference light detector, and the second optical filter cuts, of the light included in the wavelength range of the measurement light, light from a wavelength longer than the wavelength of the laser light but shorter than the longest wavelength in the wavelength range cut by the first optical filter to a wavelength longer than the longest wavelength in the sensitivity wavelength range of the reference light detector. ### Claim 7 (depends on 1) The interferometer of claim 1, wherein the wavelength separation filter is arranged in an optical path between the measurement light source and the beam combiner, and cuts light in at least a part of the sensitivity wavelength range of the reference light detector, of the light included in the wavelength range of the measurement light. ### Claim 8 (depends on 7) The interferometer of claim 7, wherein the wavelength separation filter cuts, of the light included in the wavelength range of the measurement light, light from a wavelength shorter than a shortest wavelength in the sensitivity wavelength range of the reference light detector to a wavelength longer than a longest wavelength in the sensitivity wavelength range of the reference light detector but shorter than a shortest wavelength in the sensitivity wavelength range of the measurement light detector. ### Claim 9 (depends on 1) The interferometer of claim 1, wherein the reference light detector is formed with a silicon photodiode, and the wavelength of the laser light is equal to or less than 1100 nm. ### Claim 10 (depends on 1) The interferometer of claim 1, wherein the reference light source is formed with an end surface on a light emission side of a light guide member that takes in and guides light emitted from a light emission surface. ### Claim 11 (depends on 1) A spectrometer comprising: the interferometer of claim 1; a signal processing portion that generates, based on a result of detection by the reference light detector of the interferometer, a signal indicating timing at which an output from the measurement light detector is sampled; and a spectrum generation portion that samples the output from the measurement light detector in synchronization with the signal, and that generates a spectrum indicating an intensity of light per wavelength.