Scanning method for uniform, normal-incidence imaging of spherical surface with a single beam

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;
• the spherical imaging system is constructed such that a sample having a spherical outer surface and a center of curvature defining a field of view is disposed in the optical path between the first off-axis parabolic mirror and the detector,
• the spherical imaging system is constructed such that with the sample so disposed, the center of curvature of the sample is disposed at the objective focal point of the first off-axis parabolic mirror,
• the spherical imaging system including the first off-axis parabolic mirror is constructed such that the first off-axis parabolic mirror geometrically transforms the spherical surface of the sample to be imaged as a flat rectilinear image located at a plane above the clear aperture of the first off-axis parabolic mirror, the flat rectilinear image is then remapped by the spherical imaging system into a coordinate grid, and
• the spherical imaging system is constructed 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 between the illumination source and the first off-axis parabolic mirror to scan the single beam of illumination energy along the clear aperture of the off-axis parabolic mirror as the single beam of illumination energy impinges on the clear aperture of the first off-axis parabolic mirror such that the single beam of illumination scans different portions of the sample and such that the single beam of illumination energy remains parallel to the optical axis of the first off-axis parabolic mirror.