# US 2018/0020913 A1 · Scanning Method for Uniform, Normal-Incidence Imaging of Spherical Surface with a Single Beam > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0020913 A1 - Document ID: US20180020913A1 - Status: Published application - Kind: A1 - Application number: 15/549,973 - Filed: 2016-02-16 - Published: 2018-01-25 - Earliest claimed: 2015-02-13 - Assignees: The Regents of the University of California - Applicants: The Regents of the University of California - Inventors: Warren S. Grundfest; Shijun Sung; Zachary Taylor - Web page: https://patentgrep.com/patent/US20180020913A1 ## CPC - A61B 3/1025: {for confocal scanning} - A61B 3/0008: {provided with illuminating means (A61B3/117, A61B3/14 take precedence)} - A61B 3/107: for determining the shape or measuring the curvature of the cornea - A61B 3/14: Arrangements specially adapted for eye photography - G01B 11/2518: {Projection by scanning of the object} - G02B 5/10: with curved faces - G02B 17/0832: {off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements} - G02B 26/10: Scanning systems - G02B 26/101: {with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129)} - G03B 17/17: with reflectors arranged in beam forming the photographic image, e.g. for reducing dimensions of camera - G03B 37/06: involving anamorphosis (G03B37/02, G03B37/04 take precedence) - G03B 42/00: Obtaining records using waves other than optical waves; Visualisation of such records by using optical means - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) ## Abstract Methods and systems for single beam scanning capable of imaging the surface of a spherical body of arbitrary radius of curvature are provided. The spherical imaging methods and systems utilize one or more off-axis parabolic (OAP) mirror to perform a geometrical transformation of the spherical surface to a flat rectilinear imaging coordinate grid such that the single scanning beam maintains a normal incidence across the curved field of view of the spherical body. The imaging methods and systems project the spherical surface to a Cartesian plane and then the remapped surface is rapidly imaged by raster-scanning an illumination beam in the rectangular coordinate such that the OAP mirror produces a rectilinear image of the target. The imaging of the spherical surface is accomplished while maintaining the target, illumination source, and detector in a stationary position. The imaging systems and methods may utilize a single source and a single detector, and may incorporate a THz illumination source. The beam scanning imaging systems and methods may be applied to corneal tissue imaging. ## Claims ### Claim 1 An spherical imaging system comprising: an illumination source for producing a single beam of illumination energy, and a detector for detecting a reflected beam of illumination energy, the illumination source and detector defining an optical path along which the illumination energy travels between the illumination source and the detector; a first off-axis parabolic mirror having an optical axis, an effective focal point and a clear aperture, the first off-axis parabolic mirror being disposed in the optical path; a sample having a spherical outer surface and a center of curvature defining a field of view, the sample being disposed in the optical path between the first off-axis parabolic mirror and the detector such that the center of curvature of the sample is disposed at the objective focal point of the first off-axis parabolic mirror, such that the first off-axis parabolic mirror geometrically transforms the spherical surface of the sample to a flat rectilinear imaging coordinate grid at the clear aperture of the first off-axis parabolic mirror, and such that the single beam of illumination energy maintains a normal incidence to the spherical surface of the sample across the field of view; and a scanning optic disposed in the optical path at least between the illumination source and the first off-axis parabolic mirror for modulating the single beam of illumination energy impinging on the first off-axis parabolic mirror along the clear aperture thereof such that the single beam of illumination energy samples different portions of the target and such that the single beam of illumination energy remains parallel to the optical axis of the first off-axis parabolic mirror. ### Claim 2 (depends on 1) The imaging system of claim 1, wherein the beam of illuminating energy incident on the first off-axis parabolic mirror and the illuminating energy reflected from the first off-axis parabolic mirror are coextensive, the optical path being arranged in a split beam path. ### Claim 3 (depends on 2) The imaging system of claim 2, further comprising a beam splitter disposed between the illumination source and the detector. ### Claim 4 (depends on 1) The imaging system of claim 1, further comprising at least a second off-axis parabolic mirror disposed in the optical path between the illumination source and the scanning optic and oriented to eliminate off-axis and geometric distortions in the single beam of illuminating energy. ### Claim 5 (depends on 1) The imaging system of claim 1, further comprising at least a third off-axis parabolic mirror disposed in the optical path between the detector and the first off-axis parabolic mirror and being oriented to eliminate off-axis and geometric distortions in the detected single beam of illuminating energy. ### Claim 6 (depends on 1) The imaging system of claim 1, wherein the illumination source produces a single beam of illumination energy having a THz wavelength, and wherein the sample is a cornea. ### Claim 7 (depends on 1) The imaging system of claim 1, wherein the off-axis parabolic mirror is a 90° off-axis parabolic mirror. ### Claim 8 (depends on 1) The imaging system of claim 1, wherein the illumination energy from the illumination source is collimated. ### Claim 9 (depends on 1) The imaging system of claim 1, wherein the sample is not in contact with any element of the spherical imaging system. ### Claim 10 (depends on 1) The imaging system of claim 1, wherein the source, detector, and the target are in configured to remain in static positions relative to each other. ### Claim 11 A method of imaging a spherical object comprising: providing a first off-axis parabolic mirror having an optical axis, an effective focal point and a clear aperture; disposing a sample having a spherical outer surface and a center of curvature defining a field of view in relation to the first off-axis parabolic mirror such that the center of curvature of the sample is disposed at the first focal point of the first off-axis parabolic mirror, such that the first off-axis parabolic mirror geometrically transforms the spherical surface of the sample to a flat rectilinear imaging coordinate grid at the clear aperture of the first off-axis parabolic mirror; illuminating and scanning the first off-axis parabolic mirror with a single beam of illumination energy along the clear aperture thereof such that the single beam of illumination energy samples different portions of the target, such that the single beam of illumination energy remains parallel to the optical axis of the first off-axis parabolic mirror, and such that the single beam of illumination energy maintains a normal incidence to the spherical surface of the sample across the field of view; and detecting the single beam of illuminating energy reflected off the surface of the first off-axis parabolic mirror. ### Claim 12 (depends on 11) The method of claim 11, wherein the beam of illuminating energy incident on the objective off-axis parabolic mirror and the illuminating energy reflected from the objective off-axis parabolic mirror are coextensive. ### Claim 13 (depends on 12) The method of claim 12, further comprising disposing a beam splitter between the illumination source and the detector. ### Claim 14 (depends on 11) The method of claim 11, further comprising disposing at least a second off-axis parabolic mirror adjacent the illumination source oriented to eliminate off-axis and geometric distortions in the single beam of illuminating energy. ### Claim 15 (depends on 11) The method of claim 11, further comprising disposing at least a third off-axis parabolic mirror adjacent the detector oriented to eliminate off-axis and geometric distortions in the detected single beam of illuminating energy. ### Claim 16 (depends on 11) The method of claim 11, wherein the illumination energy has a THz wavelength, and wherein the sample is a cornea. ### Claim 17 (depends on 11) The method of claim 11, wherein the off-axis parabolic mirror is a 90° off-axis parabolic mirror. ### Claim 18 (depends on 11) The method of claim 11, wherein the illumination energy is collimated. ### Claim 19 (depends on 11) The method of claim 11, wherein the sample is disposed in a non-contact position relative to any element of the spherical imaging system. ### Claim 20 (depends on 11) The method of claim 11, wherein the sample, a source of the illumination energy and a detector for the detecting are held stationary relative to each other during the imaging.