# US 10,481,084 B2 · Advanced reference detector for infrared spectroscopy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,084 B2 - Document ID: US10481084B2 - Status: Granted - Kind: B2 - Application number: 16/034,417 - Filed: 2018-07-13 - Published: 2019-01-17 - Granted: 2019-11-19 - Earliest claimed: 2017-07-14 - Assignees: Thermo Electron Scientific Instruments LLC - Applicants: Thermo Electron Scientific Instruments LLC - Inventors: John Magie Coffin - Web page: https://patentgrep.com/patent/US10481084B2 ## CPC - G01N 21/3577: for analysing liquids, e.g. polluted water - G01J 3/0208: {using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction} - G01J 3/021: {using plane or convex mirrors, parallel phase plates, or particular reflectors} - G01J 3/0229: {using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters} - G01J 3/108: {for measurement in the infrared range} - G01J 3/26: using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters - G01J 3/28: Investigating the spectrum (using colour filters G01J3/51) - G01J 3/45: Interferometric spectrometry - G01N 21/3504: for analysing gases, e.g. multi-gas analysis - G01J 2003/2869: {Background correcting} - G01N 2021/3595: {using FTIR} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - 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 A spectroscopy system and method in which the optical path following the interferometer includes a Jacquinot stop having an aperture disposed substantially at its focal point. The Jacquinot stop includes a reflective surface substantially non-orthogonal to the longitudinal axis of the path and facing the source of the IR signal containing an interferogram. The aperture passes an inner portion of the incident IR signal, while the reflective surface reflects an outer portion. The reflected outer portion of the incident IR signal, which contains erroneous spectral information due to inherent flaws in the interferometer optics, is thereby effectively removed from the original incident IR signal ultimately used to irradiate the sample, and yet still be made available for use in monitoring background spectra of the sampling optics. ## Claims ### Claim 1 A spectroscopy system, comprising: an interferogram source to provide an IR signal containing an interferogram; a source path including a focal point along a path axis of a first portion of an optical path extending from said interferogram source; a Jacquinot stop including an aperture disposed substantially at said focal point, and a reflective surface substantially non-orthogonal to said path axis and facing said interferogram source, wherein said aperture passes an inner portion of said IR signal as an incident portion of said IR signal, and said reflective surface reflects an outer portion of said IR signal as a reflected portion of said IR signal; and a reference detection device to detect said reflected portion of said IR signal. ### Claim 2 (depends on 1) The spectroscopy system of claim 1, wherein: said aperture comprises an optical opening to pass a radially inward portion of said IR signal; and said reflective surface reflects a radially outward portion of said IR signal. ### Claim 3 (depends on 1) The spectroscopy system of claim 1, wherein: said reflective surface comprises a curved surface; and said aperture is disposed near a vertex of said curved surface. ### Claim 4 (depends on 1) The spectroscopy system of claim 1, wherein said interferogram source comprises: an infrared (IR) source to emit IR energy; an interferometer to produce and combine fixed and variable reflections of said IR energy; and a mirror disposed to reflect said combined fixed and variable reflections of said IR energy. ### Claim 5 (depends on 1) The spectroscopy system of claim 1, wherein said interferogram source comprises a Michelson interferometer. ### Claim 6 (depends on 1) The spectroscopy system of claim 1, wherein said reference detection device comprises an infrared detector. ### Claim 7 (depends on 1) The spectroscopy system of claim 1, wherein said reference detection device comprises: a mirror disposed to further reflect said reflected portion of said IR signal; and an infrared detector to receive said further reflected portion of said IR signal. ### Claim 8 (depends on 1) The spectroscopy system of claim 1, further comprising a sample detection device to detect at least a portion of said IR signal. ### Claim 9 (depends on 8) The spectroscopy system of claim 8, wherein said sample detection device comprises an infrared detector. ### Claim 10 (depends on 8) The spectroscopy system of claim 8, wherein said sample detection device comprises: a mirror disposed to reflect said at least a portion of said IR signal; and an infrared detector to receive said reflected at least a portion of said IR signal. ### Claim 11 A spectroscopy method, comprising: generating, with an interferogram source, an IR signal containing an interferogram; conveying said IR signal via a light path including a focal point along a path axis of a first portion of an optical path extending from said interferogram source; passing an inner portion of said IR signal as an incident portion of said IR signal via an aperture of a Jacquinot stop disposed substantially at said focal point and including a reflective surface substantially non-orthogonal to said path axis and facing said interferogram source; reflecting, via said reflective surface, an outer portion of said IR signal as a reflected portion of said IR signal; and detecting said reflected portion of said IR signal. ### Claim 12 (depends on 11) The spectroscopy method of claim 11, wherein: said passing an inner portion of said IR signal via an aperture passing a radially inward portion of said IR signal via an optical opening; and said reflecting, via said reflective surface, an outer portion of said IR signal comprises reflecting a radially outward portion of said IR signal. ### Claim 13 (depends on 12) The spectroscopy method of claim 12, wherein: said reflecting a radially outward portion of said IR signal comprises reflecting said radially outward portion of said IR signal via a curved surface; and said passing a radially inward portion of said IR signal via an optical opening comprises passing a radially inward portion of said IR signal at a vertex of said curved surface. ### Claim 14 (depends on 11) The spectroscopy method of claim 11, wherein said generating, with an interferogram source, an IR signal containing an interferogram comprises: generating IR energy; producing and combining fixed and variable reflections of said IR energy; and reflecting said combined fixed and variable reflections of said IR energy. ### Claim 15 (depends on 11) The spectroscopy method of claim 11, wherein said generating, with an interferogram source, an IR signal containing an interferogram comprises generating said IR signal with a Michelson interferometer. ### Claim 16 (depends on 11) The spectroscopy method of claim 11, wherein said detecting said reflected portion of said interferogram comprises receiving said reflected portion of said interferogram with an infrared detector. ### Claim 17 (depends on 11) The spectroscopy method of claim 11, wherein said detecting said reflected portion of said IR signal comprises: further reflecting said reflected portion of said IR signal; and receiving said further reflected portion of said IR signal with an infrared detector. ### Claim 18 (depends on 11) The spectroscopy method of claim 11, further comprising detecting at least a portion of said IR signal. ### Claim 19 (depends on 18) The spectroscopy method of claim 18, wherein said detecting at least a portion of said IR signal comprises receiving said at least a portion of said IR signal with an infrared detector. ### Claim 20 (depends on 18) The spectroscopy method of claim 18, wherein said detecting at least a portion of said IR signal comprises: reflecting said at least a portion of said IR signal; and receiving said reflected at least a portion of said IR signal with an infrared detector.