A catadioptric optical system in sequence of ray tracing comprises a first mirrors group of Ritchey-Chrtien type hyperbolic mirrors with positive diopter including a concave primary mirror having a central through hole and a convex secondary mirror, a second corrector lens group with negative diopter positioned at the image-side of the first mirrors group including a first meniscus lens element having positive refractive power and a convex object-side surface, a second lens element having negative refractive power and biconcave surfaces, a third meniscus lens element having negative refractive power and a concave object-side surface, and a fourth lens element having positive refractive power and biconvex surfaces. The infinite conjugate beams of incident light within field of view pass through the catadioptric optical system to become a corrected beam having a small CRA angle.

A projection optical system that enlarges and projects an image displayed on an image display includes: a first optical system; and a second optical system. The projection optical system is a monofocal lens or a zoom lens. The first optical system and the second optical system are arranged, in order starting with the first optical system, from an enlargement side of the projection optical system. The second optical system forms an intermediate image of the image between the first optical system and the second optical system. The first optical system enlarges and projects the intermediate image. The first optical system includes: a first-A optical system and a first-B optical system in order from the enlargement side; and a reflecting optical element that bends a light path between the first-A optical system and the first-B optical system.

An optical system in which an aggressively compact reflective front end is combined with beam splitting elements and refractive relay optics to allow several imaging systems working in widely different wavelength bands to share a common aperture. The aggressively compact design results in significant field curvature at the uncorrected intermediate or virtual focus, which is corrected in the refractive relay optics for each band's imaging path.

A beam expander including a partial reflector, a reflective polarizer curved about two orthogonal axes and a quarter wave retarder disposed between the reflective polarizer and the partial reflector is described. The beam expander is adapted to receive an input light beam incident on the partial reflector and transmit an expanded output light beam. Illuminators and projection systems including the beam expander are described.

Eye-tracked head-mounted displays are provide which, in one aspect, may utilize the same optics for eyetracking and image viewing, with a selected portion of the optics used for an eyetracking optical path and a selected portion of the display optics used for an image viewing optical path.

A projection optical system (2) projects from a DMD (7) on a reducing side onto a screen (9) on an enlargement side, and includes: a first refractive optical system (10) that forms a first intermediate image (51) on the enlargement side using light incident from the reducing side; a second refractive optical system (20) that forms the first intermediate image (51) on the reducing side into a second intermediate image (52) on the enlargement side; and a first reflective optical system (30) including a first reflective surface (31a) with positive refractive power that is positioned on the enlargement side of the second intermediate image (52), wherein the second refractive optical system (20) includes a first focus lens group (61) that moves when focusing is carried out, and the first focus lens group (61) includes at least one lens (L13) included in the second refractive optical system (20).

An optical system (e.g., a telescope) comprising an optical assembly that reflects and refracts light rays through a single window about an optical path to a detector. A field-of-view switch assembly comprises a mount, having a pair of diverter mirrors, movably coupled to the optical assembly and being selectively movable between a non-bypass position and a bypass position. The diverter mirrors bypass a first field-of-view and translate a second field-of-view (both through the single window) when moved from the non-bypass position to the bypass position to redirect the optical path. The diverter mirrors straddle the optical path in the non-bypass position. A dynamic shutter shields the second diverter mirror and exposes the second diverter mirror when moved between non-bypass and bypass positions. A four-bar linkage mechanism rotates the mount with an on-board motor and a torsional shaft to absorb impact forces. Associated methods are provided for facilitating switching between fields-of-view.

Optical systems including an image surface, a stop surface, a partial reflector disposed between the image surface and the stop surface, a reflective polarizer disposed between the stop surface and the partial reflector, and a quarter wave retarder disposed between the reflective polarizer and the partial reflector are described. The reflective polarizer is convex along two orthogonal axes. The reflective polarizer may be a thermoformed multilayer reflective polarizer.

A compact, uniaxially-aligned series of lenses are shaped and coated to allow coaxial viewing of two different fields of view on the same focal-plane array by selecting a type of light. The selection can be, for example, by spectrum or polarization. Zonal coatings on the lens surfaces permit for a catadioptric narrow field-of-view light path. The lens assembly accomplishes simultaneous dual field-of-view in a durable package without respective motion of optical elements, without substantial gaps between the lenses, and at lower cost than other assemblies.

Optical systems including an image surface and an exit surface are described. First second and third optical lenses, a partial reflector, a multilayer reflective polarizer and a retarder are disposed between the image surface and the exit surface. At least one location on at least one layer of the multilayer reflective polarizer is substantially uniaxially oriented. Each chief light ray that passes from the image surface to the exit surface is incident on the multilayer reflective polarizer with an angle of incidence less than about 30 degrees. The optical system may include a plurality of major surfaces disposed between the image surface and the exit surface where each major surface is convex toward the image surface and where at least six different major surfaces have six different convexities.