The present disclosure provides an optical imaging lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens having refractive power; a second lens having refractive power; and a third lens having refractive power. A distance BFL along the optical axis from an image-side surface of the third lens of the optical imaging lens assembly to an imaging plane of the optical imaging lens assembly and a distance Td along the optical axis from an object-side surface of the first lens to the image-side surface of the third lens satisfy: 4.5≤BFL/Td≤7.0.

A virtual image display device includes a display element, which is an image light generating unit that generates an image light, a first mirror that reflects the image light, a second mirror that reflects the image light reflected by the first mirror, and a third mirror that transmits external light and that reflects part of the image light reflected by the second mirror to guide the image light to a position of an exit pupil, wherein the first mirror has an angular dependence on a reflective surface.

A system consists of a front group, a slit member, and a rear group arranged in order from an object side to an image side, wherein the slit member is provided with an aperture long in a first direction, wherein the front group does not form an image of an object on the aperture in a first cross section parallel to the first direction, and forms an intermediate image of the object on the aperture in a second cross section perpendicular to the first direction, wherein the rear group includes a diffractive surface configured to collects a plurality of rays at positions different from each other in the second cross section, wherein the front group includes a first reflective surface and a second reflective surface that satisfies a predetermined inequality.

An imaging system, including a light valve and a projection lens, is provided. The projection lens has a reduction side and a magnification side, and includes a lens group and a convex mirror. The light valve is configured on the reduction side. The projection lens is configured to image the beam from the light valve on a projection surface, and the projection surface is configured on the magnification side. There is an included angle between the projection surface and a light receiving surface. The lens group is configured on an optical path between the magnification side and the reduction side, and includes first to seventh lens elements sequentially arranged from the magnification side to the reduction side. The refractive powers of the first to seventh lens elements are respectively negative, negative, positive, positive, negative, positive, and positive. The convex mirror is configured on an optical path between the lens group and the magnification side. A projection device, including the imaging system, is also provided.

An apparatus includes multiple optical elements arranged along an optical path between an entrance aperture and an exit aperture, configured to image an object at infinity to an image at infinity and defining an exit pupil for light at the exit aperture, the image have a magnification, M, in a range from 7× to 15×. The optical elements include four non-planar mirrors. The apparatus also includes a connector configured to attach the apparatus to a mobile device having a camera with the exit pupil of the plurality of optical elements aligned with an entrance pupil of the camera of the mobile device.

Optical system includes a front group, light-shielding member, and rear group that are arranged in this order in direction from object side toward image side. The light-shielding member is provided with opening elongated in first direction. The front group does not image the object at the opening in first section parallel to the first direction and forms intermediate image of the object at the opening in second section perpendicular to the first direction. The rear group has diffractive surface that splits light beam that passes through the opening into light beams at different wavelengths in the second section and focuses the light beams on different locations in the second section. Light beam that is emitted from the front group 11 and that enters the opening is non-parallel light in the first section.

A light guide member (10) includes three surfaces of a second surface (S12), a fourth surface (S14), and a fifth surface (S15) as two or more non-axisymmetric curved surfaces, and a projection lens (30) includes a lens surface (31a) as a non-axisymmetric aspheric surface. With this, on the light guide member side, even when there is a shape constraint that the first surface (S11) or the third surface (S13) which is a surface contributing to light guide is a flat surface, and correction of asymmetric aberration is limited, it becomes possible to perform sufficient aberration correction as the whole of an optical system including the projection lens. Therefore, the virtual image display apparatus can have a wide viewing angle and high performance, and can be made small and lightweight.

A cata-dioptric optical system for high resolution imaging in visible and infrared bands. The system includes a concave primary mirror, a convex secondary mirror, at least one beam splitter, a first folding mirror, a first group of lenses, a second group of lenses, and at least two image planes. The image planes have one or more aggregated sensors, where a first image plane receives rays from the first group of lenses and a second image plane receives rays from the second group of lenses, and at least one image plane is positioned behind the primary mirror and at a radial distance from the optical axis that is no more than the radius of the primary mirror.

A spectrograph that includes camera focusing optics with a primary mirror having a concave-shaped reflective mirror surface, a secondary mirror having a convex-shaped reflective mirror surface and positioned to receive light reflected by the primary mirror, a tertiary mirror having a concave reflective mirror surface and positioned to receive light reflected by the secondary mirror, and a field correcting lens comprising a convex lens surface in combination with a concave lens surface, wherein light received by said field correcting lens from said tertiary mirror enters said convex lens surface, traverses said field correcting lens, and exits from said concave lens surface. The optional field correcting lens is positioned such that the primary mirror, secondary mirror, tertiary mirror, and the field correcting lens share the common parent vertex axis.

A pulse multiplier includes a beam splitter and one or more mirrors. The beam splitter receives a series of input laser pulses and directs part of the energy of each pulse into a ring cavity. After circulating around the ring cavity, part of the pulse energy leaves the ring cavity through the beam splitter and part of the energy is recirculated. By selecting the ring cavity optical path length, the repetition rate of an output series of laser pulses can be made to be a multiple of the input repetition rate. The relative energies of the output pulses can be controlled by choosing the transmission and reflection coefficients of the beam splitter. This pulse multiplier can inexpensively reduce the peak power per pulse while increasing the number of pulses per second with minimal total power loss.