Abstract: A polarizing beam splitting system is described. The polarizing beam splitting system may include first and second prisms where the volume of the first prism is no greater than half the volume of the second prism. The first prism includes first and second surfaces and a light source may be disposed adjacent the first surface and an image forming device may be disposed adjacent the second surface. The first prism has a first hypotenuse and the second prism has a second hypotenuse. A reflective polarizer is disposed between the first and second hypotenuses.

Abstract: 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.

Abstract: A head-mounted display including a first optical system is described. The first optical system includes a partial reflector and a multilayer reflective polarizer disposed adjacent to and spaced apart from the partial reflector. The multilayer reflective polarizer is curved about orthogonal first and second axes and includes at least one layer that is substantially optically uniaxial at at least one location. Each chief ray that passes through the first optical system is first incident on the multilayer reflective polarizer at an angle of incidence less than 30 degrees.

Abstract: Methods of making optical films and optical stacks are described. A method of making an optical lens molded to a first curved optical film includes providing a first optical film including alternating first and second polymeric layers; providing a thermoform tool having a curved surface; heating and conforming the first optical film to the curved surface to form a first curved optical film; and molding an optical lens onto the first curved optical film.

Abstract: Optical systems including an image surface and a stop surface are described. First second and third optical lenses, a partial reflector, a multilayer reflective polarizer and a quarter wave retarder are disposed between the image surface and the stop surface. A plurality of major surfaces are disposed between the image surface and the stop surface with each major surface convex toward the image surface along orthogonal first and second axes. At least six different major surfaces have six different convexities.

Abstract: 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.

Abstract: 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.

Abstract: A multilayer reflective polarizer convex along orthogonal first and second axes orthogonal to an optical axis passing thorough an apex of the multilayer reflective polarizer is described. The multilayer reflective polarizer has at least one first location having a radial distance r1 from the optical axis and a displacement s1 from a plane perpendicular to the optical axis at the apex, where s1/r1 is in a range of about 0.2 to about 0.8. The multilayer reflective polarizer may have at least one inner layer substantially optically uniaxial at at least one first location away from the apex. For an area of the reflective polarizer defined by s1 and r1, a maximum variation of a transmission axis of the reflective polarizer may be less than about 2 degrees.

Abstract: 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.

Abstract: A folded light path illuminator is provided. The illuminator may include a polarizing beam splitter having an input face, an output face and an imager face, a light source disposed adjacent the input face and defining an input active area on the input face, and an image forming device disposed adjacent the imager face for receiving light emitted from the light source and emitting a patterned light, which may be a converging patterned light. The image forming device may have a largest image area which defines an output active area on the output face. One or both of the input active area and the output active area may be less than about half the largest image area. The polarizing beam splitter may include first and second prisms and the volume of the first prism may be no greater than half the volume of the second prism.

Abstract: Methods of making optical films and optical stacks are described. A method of making an optical stack includes providing a thermoform tool centered on a tool axis and having an external surface rotationally asymmetric about the tool axis; heating an optical film resulting in a softened optical film; conforming the softened optical film to the external surface while stretching the softened film along at least orthogonal first and second directions away from the tool axis resulting in a conformed optical film rotationally asymmetric about an optical axis of the conformed film where the optical axis coincident with the tool axis; cooling the conformed optical film resulting in a symmetric optical film rotationally symmetric about the optical axis; and molding an optical lens on the symmetric optical film resulting in the optical stack.

Abstract: A head-mounted display including a first optical system is provided. The first optical system includes an image surface, a stop surface, a first optical stack disposed between the image surface and the stop surface and a second optical stack disposed between the first optical stack and the stop surface. The first optical stack includes a first optical lens and a partial reflector. The second optical stack includes a second optical lens and a curved multilayer reflective polarizer. A quarter wave retarder is disposed between the multilayer reflective polarizer and the partial reflector. The multilayer reflective polarizer and the partial reflector may be convex toward the image surface along orthogonal first and second axes.

Abstract: Provided are devices for applying actinic radiation to a curable resin. The devices include a housing having a front face, an actinic radiation source arranged within the housing such that actinic radiation emerges from the housing through the front face, and a proximity detector. The proximity detector is functionally connected to the actinic radiation source such that the actinic radiation source is shut off unless the proximity detector detects the presence of a surface within a safe distance from the front face. Optionally, the device includes a surface temperature sensor functionally connected to the actinic radiation source such that the actinic radiation source is shut off if the surface temperature sensor senses a surface temperature exceeding a maximum safe surface temperature.

Abstract: 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.

Abstract: A 3D imaging apparatus with enhanced depth of field to obtain electronic images of an object for use in generating a 3D digital model of the object. The apparatus includes a housing having mirrors positioned to receive an image from an object external to the housing and provide the image to an image sensor. The optical path between the object and the image sensor includes an aperture element having apertures for providing the image along multiple optical channels with a lens positioned within each of the optical channels. The depth of field of the apparatus includes the housing, allowing placement of the housing directly on the object when obtaining images of it.

Abstract: A multilayer reflective polarizer substantially rotationally symmetric about an optical axis passing thorough an apex of the multilayer reflective polarizer and convex along orthogonal first and second axes orthogonal to the optical axis is described. The multilayer reflective polarizer has at least one first location having a radial distance r1 from the optical axis and a displacement s1 from a plane perpendicular to the optical axis at the apex, where s1/r1 is at least 0.1. The multilayer reflective polarizer may have at least one inner layer substantially optically uniaxial at at least one first location away from the apex. For an area of the reflective polarizer defined by s1 and r1, a maximum variation of a transmission axis of the reflective polarizer may be less than about 2 degrees.

Abstract: 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.

Abstract: Optical systems including first and second optical stacks and adapted to provide an adjustable dioptric correction are described. The first optical stack includes a first optical lens and a partial reflector. The second optical stack is convex along orthogonal first and second axes and includes a second optical lens and a reflective polarizer. The reflective polarizer has at least one first location having a radial distance r1 from an optical axis of the second optical stack 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. A quarter wave retarder is disposed between the second optical stack and the first optical stack.

Abstract: A light irradiation device that emits a light patch of uniform intensity. The device may be a dental light wand. The device has a light source, a lenslet array and an optional relay lens. The light source may be a laser or a collimated LED. Each lenslet of the lenslet array has two convex surfaces, a front convex surface, and a rear convex surface that is opposite to the front convex surface. The front convex surface has a focal point on the principal plane of the rear convex surface. The focal length of the front convex surface differs from the focal length of the rear convex surface. Light beams emitted by the light source pass through the lenslet array, and if a relay lens is present then pass through the relay lens, forming a light patch of uniform intensity.

Abstract: A head-mounted display including a first optical system is provided. The first optical system includes an image surface, a stop surface, a first optical stack disposed between the image surface and the stop surface and a second optical stack disposed between the first optical stack and the stop surface. The first optical stack includes a first optical lens and a partial reflector. The second optical stack includes a second optical lens and a curved multilayer reflective polarizer. A quarter wave retarder is disposed between the multilayer reflective polarizer and the partial reflector. The multilayer reflective polarizer and the partial reflector may be convex toward the image surface along orthogonal first and second axes.