# US 7,609,381 B2 · Compact, high-throughput spectrometer apparatus for hyperspectral remote sensing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,381 B2 - Document ID: US7609381B2 - Status: Granted - Kind: B2 - Application number: 12/052,705 - Filed: 2008-03-20 - Published: 2009-09-24 - Granted: 2009-10-27 - Earliest claimed: 2008-03-20 - Assignees: The Aerospace Corporation - Inventors: David Wheeler Warren - Web page: https://patentgrep.com/patent/US7609381B2 ## CPC - G01J 3/02: Details - 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 3/18: using diffraction elements, e.g. grating (gratings per se G02B) - 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 spectrometer apparatus includes a refractor element, a slit, a detector, a diffraction grating, and a corrector lens. The refractor element includes a rear surface and a front surface. The slit provides an optical path to the rear surface of the refractor element, and is configured to transmit an image incident thereupon along the optical path. The detector is positioned facing the rear surface of the refractor element. The diffraction grating faces the front surface of the refractor element, and is configured to spectrally disperse and reimage the image of the slit toward the front surface of the refractor element. The corrector lens is positioned between the refractor element and the diffraction grating such that the image is provided to the detector corrected for a spherical aberration caused by a separation distance between the detector and the rear surface of the refractor element. ## Claims ### Claim 1 A spectrometer apparatus comprising: a refractor element including a rear surface and a front surface; a slit configured to transmit an image incident thereupon along an optical path to the rear surface of the refractor element; a detector positioned facing the rear surface of the refractor element; a diffraction grating facing the front surface of the refractor element, the diffraction grating being configured to spectrally disperse and reimage the image of the slit toward the front surface of the refractor element; and a corrector lens positioned between the refractor element and the diffraction grating such that the image is provided to the detector corrected for a spherical aberration caused by a separation distance between the detector and the rear surface of the refractor element. ### Claim 2 (depends on 1) The spectrometer apparatus of claim 1, wherein the refractor element is a modified Dyson lens. ### Claim 3 (depends on 1) The spectrometer apparatus of claim 1, wherein the refractor element is a truncated modified Dyson lens. ### Claim 4 (depends on 1) The spectrometer apparatus of claim 1, wherein the front surface of the refractor element is not concentric in relation to the slit. ### Claim 5 (depends on 1) The spectrometer apparatus of claim 1, wherein the front surface of the refractor element is convex and spherical. ### Claim 6 (depends on 5) The spectrometer apparatus of claim 5, wherein the rear surface of the refractor element is plano or convex and spherical. ### Claim 7 (depends on 1) The spectrometer apparatus of claim 1, wherein the diffraction grating is concave and spherical. ### Claim 8 (depends on 1) The spectrometer apparatus of claim 1, wherein the corrector lens includes an aspheric surface facing the diffraction grating. ### Claim 9 (depends on 1) The spectrometer apparatus of claim 1, wherein the refractor element and corrector lens are made from ZnSe. ### Claim 10 (depends on 1) The spectrometer apparatus of claim 1, wherein the refractor element is made from sodium chloride (NaCl). ### Claim 11 (depends on 1) The spectrometer apparatus of claim 1, wherein the refractor element and corrector lens are made from fused silica. ### Claim 12 (depends on 1) The spectrometer apparatus of claim 1, wherein the detector is tilted in relation to the rear surface of the refractor element. ### Claim 13 (depends on 1) The spectrometer apparatus of claim 1, further including: a mirror between the slit and the rear surface of the refractor element. ### Claim 14 (depends on 1) The spectrometer apparatus of claim 1, further including: an imager section configured to provide a telecentric image to the slit. ### Claim 15 (depends on 14) The spectrometer apparatus of claim 14, wherein the imager section includes an imaging objective. ### Claim 16 (depends on 15) The spectrometer apparatus of claim 15, wherein the imager section includes a fold mirror positioned between the imaging objective and the slit. ### Claim 17 A spectrometer apparatus comprising: a refractor element including a rear surface and a front surface; a slit configured to transmit an image incident thereupon along an optical path to the rear surface of the refractor element; a detector positioned facing the rear surface of the refractor element; and a diffraction grating facing the front surface of the refractor element, the diffraction grating being configured to spectrally disperse and reimage the image of the slit toward the front surface of the refractor element such that the image is provided to the detector corrected for a spherical aberration caused by a separation distance between the detector and the rear surface of the refractor element. ### Claim 18 (depends on 17) The spectrometer apparatus of claim 17, wherein the diffraction grating is radially aspheric. ### Claim 19 (depends on 17) The spectrometer apparatus of claim 17, wherein the diffraction grating is a mechanical ruling. ### Claim 20 (depends on 17) The spectrometer apparatus of claim 17, wherein the diffraction grating is a non-mechanical ruling. ### Claim 21 (depends on 17) The spectrometer apparatus of claim 17, wherein the diffraction grating is produced by electron beam or x-ray lithography. ### Claim 22 (depends on 17) The spectrometer apparatus of claim 17, wherein the diffraction grating is holographic. ### Claim 23 (depends on 17) The spectrometer apparatus of claim 17, wherein the refractor element is a truncated modified Dyson lens. ### Claim 24 (depends on 17) The spectrometer apparatus of claim 17, wherein the front surface of the refractor element is not concentric in relation to the slit. ### Claim 25 (depends on 17) The spectrometer apparatus of claim 17, wherein the front surface of the refractor element is convex and spherical.