Widefield catadioptric monolithic telescopes
View Patent ↗In one aspect, an apparatus includes a first aspheric refractive surface defined by a first polynomial and positioned to receive input light, and a first aspheric mirror surface comprising a first reflective coating, the first mirror surface defined by a second polynomial and positioned to receive light from the first aspheric refractive surface. The apparatus includes a second aspheric mirror surface comprising a second reflective coating, the second aspheric mirror surface defined by a third polynomial and positioned to receive light from the first aspheric mirror surface, and a second aspheric refractive surface defined by a fourth polynomial and positioned to receive light from the second aspheric mirror surface, wherein the first aspheric refractive surface, the first aspheric mirror surface, the second aspheric mirror surface, and the second aspheric refractive surface are arranged to have a fixed alignment with respect to each other as part of a monolithic structure.
1 . An optical apparatus, comprising:
a first aspheric refractive surface defined by a first polynomial and positioned to receive input light;
a first aspheric mirror surface comprising a first reflective coating, the first aspheric mirror surface defined by a second polynomial and positioned to receive light from the first aspheric refractive surface;
a second aspheric mirror surface comprising a second reflective coating, the second aspheric mirror surface defined by a third polynomial and positioned to receive light from the first aspheric mirror surface; and
a second aspheric refractive surface defined by a fourth polynomial and positioned to receive light from the second aspheric mirror surface, the fourth polynomial configuring the second aspheric refractive surface as a field corrector plate, wherein the first aspheric refractive surface, the first aspheric mirror surface, the second aspheric mirror surface, and the second aspheric refractive surface are arranged to have a fixed alignment with respect to each other as part of a monolithic structure, wherein the first polynomial configures a shape of the first aspheric refractive surface and the fourth polynomial configures a shape of the field corrector plate, the shape of the first aspheric refractive surface and the shape of the field corrector plate together compensating for one or more of spherical, comatic, field, or astigmatic aberrations introduced by at least the first aspheric mirror surface,
wherein the shape of the first aspheric refractive surface and the shape of the field corrector plate are configured to correct high-order off-axis aberrations including at least coma and astigmatism introduced by the first and second aspheric mirror surfaces, and
wherein correction of the high-order off-axis aberrations by the first aspheric refractive surface and the field corrector plate enables the optical apparatus to operate with a wide field of view at a fast focal ratio in the monolithic structure.
2 . The optical apparatus of claim 1 , wherein the first, second, third, and fourth polynomials each have non-zero coefficients for even order terms including at least a 4th order term, a 6th order term, and an 8th order term.
3 . The optical apparatus of claim 1 , wherein the first and second aspheric mirror surfaces are at least partially defined by conic sections.
4 . The optical apparatus of claim 1 , wherein the first, second, third, and fourth polynomials each have different coefficient values from each other.
5 . The optical apparatus of claim 1 , wherein the optical apparatus comprises zinc selenide (ZnSe).
6 . The optical apparatus of claim 1 , wherein the first aspheric mirror surface has an aspherical concave shape and the second aspheric mirror surface has an aspherical convex shape.
7 . The optical apparatus of claim 1 , wherein the optical apparatus is a Cassegrain telescope and the first aspheric mirror surface is a primary mirror of the Cassegrain telescope and the second aspheric mirror surface is a secondary mirror of the Cassegrain telescope.
8 . The optical apparatus of claim 1 , wherein the first and second aspheric mirror surfaces include a metallic coating or one or more dielectric layers to cause the first and second aspheric mirror surfaces to reflect light.
9 . The optical apparatus of claim 1 , wherein the first and second aspheric refractive surfaces are coated with one or more of an anti-reflective coating or a wavelength filter.
10 . A method of manufacturing an optical system, the method comprising:
shaping, in a plurality of first areas of a block of optical material, a first aspheric refractive surface and a second aspheric refractive surface according to a plurality of first prescriptions, wherein the second aspheric refractive surface is configured as a field corrector plate;
shaping, in one or more second areas of the block of optical material, a first aspheric mirror surface and a second aspheric mirror surface according to one or more second prescriptions, wherein the first aspheric refractive surface is positioned to receive input light, the first aspheric mirror surface is positioned to receive light from the first aspheric refractive surface, the second aspheric mirror surface is positioned to received light from the first aspheric mirror surface, and the second aspheric refractive surface is positioned to receive light from the second aspheric mirror surface;
applying one or more reflective coatings to each of the first aspheric mirror surface and the second aspheric mirror surface; and
applying one or more anti-reflective coatings or filters to each of the first aspheric refractive surface and the second aspheric refractive surface to produce one or more field correction surfaces including the field corrector plate, wherein the first aspheric refractive surface and the field corrector plate together are configured to compensate for one or more of spherical, comatic, field, or astigmatic aberrations introduced by at least the first aspheric mirror surface,
wherein the first aspheric refractive surface and the field corrector plate are shaped according to the plurality of first prescriptions to correct high-order off-axis aberrations including at least coma and astigmatism introduced by the first and second aspheric mirror surfaces, and
wherein correction of the high-order off-axis aberrations by the first aspheric refractive surface and the field corrector plate enables wide field of view operation at a fast focal ratio in a monolithic catadioptric optical system.
11 . The method of claim 10 , wherein each of the plurality of first prescriptions includes a polynomial, the polynomial defining a corresponding aspheric surface and having non-zero coefficients for even order terms including at least a 4th order term, a 6th order term, and an 8th order term.
12 . The method of claim 10 , wherein each of the one or more second prescriptions includes a polynomial, the polynomial defining a corresponding aspheric surface and having non-zero coefficients for even order terms including at least a 4th order term, a 6th order term, and an 8th order term.
13 . The method of claim 10 , wherein each of the first and second prescriptions is different from each other.
14 . The method of claim 10 , wherein the block comprises zinc selenide (ZnSe).
15 . The method of claim 10 , wherein the optical system is a Cassegrain telescope.