An optical stack includes first and second lenses, a partial reflector, a reflective polarizer, and a retarder. The reflective polarizer is curved about two orthogonal axes and includes at least one layer that is substantially optically uniaxial at at least one location. An optical system includes the optical stack disposed between an image surface and an exit surface. The optical system is configured such that substantially any chief ray transmitted from the image surface to the exit surface is first incident on the reflective polarizer at an angle of incidence less than 30 degrees.

A variable magnification optical system consists of, in order from an object side, a first optical system remaining stationary during changing magnification and a second optical system including a plurality of lens groups moving during changing magnification. The first optical system includes a first mirror and a second mirror having reflective surfaces arranged to face each other. The first mirror has a reflective surface concave toward the object side. The second mirror has a reflective surface convex toward the image side. An intermediate image is formed between the second mirror and the second optical system. Predetermined conditional expressions relating to the partial dispersion ratios of the lenses included in the second optical system are satisfied.

An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, disposed in order from an object side, and a first reflection member and a second reflection member, disposed on an object side of the first lens, each having a freeform surface.

An optical lens assembly includes a first optical lens having opposing first and second major surfaces and facing a second lens having opposing third and fourth major surfaces. The second and third major surfaces face each other. The first through fourth major surfaces having respective sags, S1-S4, wherein each of the sags is defined by: (1) where c is 1/radius of curvature of the major surface, k is the conic constant of the surface, r is a distance from an optical axis, and a is an aspheric deformation constant. The first major surface includes a convex central portion surrounded by an annular concave outer portion, the second major surface is convex, the third major surface is substantially planar, and the fourth major surface is convex, wherein for r extending from about 1 mm to at least about 25 mm: ?0.7?S1/S2?1-0.2?S1/S4?0.4.

[00001]$\begin{array}{cc}S=\frac{{\mathrm{cr}}^2}{1+\sqrt{1-\left(1+k\right)c^2{r}^2}}+{?}_2{r}^4+{?}_3{r}^6+{?}_4{r}^8& \mathrm{Formula}\left(i\right)\end{array}$

An optical system includes a reflective surface, a display adapted to emit image light toward the reflective surface, and a multilayer reflective polarizer disposed proximate the reflective surface. The multilayer reflective polarizer is curved about two orthogonal axes and includes at least one layer that is substantially optically uniaxial at at least one location. The image light is transmitted by the multilayer reflective polarizer after it is first reflected by the multilayer reflective polarizer. A head-mounted display includes a first optical system and a second optical system disposed proximate the first optical system.

Integral optical stacks and optical systems including the integral optical stack are described. The integral optical stack may include first and second lenses, a partial reflector, a reflective polarizer curved about two orthogonal axes, and a quarter wave retarder. The reflective polarizer is curved about two orthogonal axes and includes at least one layer that is substantially optically biaxial at at least one first location on the at least one layer away from an optical axis of the optical stack and substantially optically uniaxial at at least one second location away from the optical axis.

An optical system and a magnifying device including the optical system are described. The optical system includes an exit pupil, a reflective polarizer proximate the exit pupil, a partial reflector disposed adjacent the reflective polarizer opposite the exit pupil, and a quarter wave retarder disposed between the reflective polarizer and the partial reflector. The reflective polarizer is curved about two orthogonal axes and the partial reflector is spaced apart from the reflective polarizer.

Disclosed are an image acquisition compound lens and application thereof. The image acquisition compound lens includes a camera lens and two or more convex mirrors having a same shape, wherein, the camera lens has a predetermined front field of view; the two or more convex mirrors having the same shape are symmetrically disposed with respect to an optical axis (c) of the camera lens within the predetermined front field of view of the camera lens, and configured to reflect partial views beside and behind the camera lens to the camera lens respectively; a mirror gap is formed between the convex mirrors symmetrically disposed, allowing the mirror lens to directly acquire views within a first front field of view right in front of the mirror lens.

Optical systems including a partial reflector, a reflective polarizer, and a quarter wave retarder disposed between the partial reflector and the reflective polarizer are described. The reflective polarizer is curved about two orthogonal axes and has at least one location having a radial distance r1 from an optical axis passing through an apex of the reflective polarizer and a displacement s1 from a plane perpendicular to the optical axis at an apex of the reflective polarizer, where s1/r1 is at least 0.1. The optical system is adapted to provide an adjustable dioptric correction.

A scope observing a scene, the scope includes a first optical sub-assembly, called the afocal module, and a second optical sub-assembly, called the display module, the afocal module comprising: a removable and switchable linear polarizer, a first polarization-splitting element, an afocal optical system the first polarization-splitting element the display module comprising: a half-wave plate, called the distribution plate, a display, an optical objective configured to collimate the display light; a second polarization-splitting element arranged after the distribution half-wave plate.