Nonsymmetric optical system and design method for nonsymmetric optical system

A nonsymmetric optical system, comprising:

• three optical components each having a respective optical surface n (n=1, 2, 3), optically coupled in a folded configuration,
• wherein each surface n has a center of curvature Cn,
• further wherein, in an unfolded configuration Cn are off-axis, and
• further wherein at least two of the optical surfaces are φ-polynomial surfaces.

A method for designing a nonsymmetric optical system, comprising:

• a) generating a well-corrected, on-axis, obscured optical system having rotationally symmetric optical surfaces and a field of view;
• b) tilting at least one of the optical surfaces to provide an unobscured form of the optical system;
• c) determining an aberration performance including one or more dominant aberrations of the unobscured optical system over the field of view, and further determining whether the one or more dominant aberrations are field constant or field dependent;
• and
• if the one or more dominant aberrations are field constant, then
• i) adding a phi (φ)-polynomial corresponding to the one or more dominant aberrations as a variable to an optical surface at or adjacent the aperture stop of the system;
• ii) optimizing the optical design;
• iii) evaluating an image quality metric;
• and
• iv) determining whether the optical system meets a performance specification and, if not, then reiterating steps (c-iv);
• or
• if the one or more dominant aberrations are field dependent, then
• v) adding a phi (φ)-polynomial corresponding to a radial order higher than the one or more dominant aberrations as variable to an optical surface that is away from the aperture stop of the system;
• vi) optimizing the optical design;
• vii) evaluating an image quality metric;
• and
• viii) determining whether the optical system meets a performance
• specification and, if not, then reiterating steps (c and v-viii).