A head-up display using a backlight to control an eyebox, is applicable to being used with an imaging semi-reflective mirror, and includes a backlight source, a switchable adjustment mirror device, a backlight concave mirror, a display panel and an imaging concave mirror. The switchable adjustment mirror device is positioned at the light path between the backlight source and the backlight concave mirror and includes a plurality of mirrors having different curvatures, and each one of the mirrors can be selected to reflect the backlight beam from the backlight source to the backlight concave mirror. Accordingly, the position of the eyebox can be controlled to match with the position of the eyes of the viewer.

An off-axis three-mirror optical system with freeform surfaces comprised an aperture, a primary mirror, a secondary mirror, a tertiary mirror, and a detector. The aperture is located on an incident light path. The primary mirror is located on an aperture side. The secondary mirror is located on a primary mirror reflected light path. The tertiary mirror is located on a secondary mirror reflected light path. The detector located on a tertiary mirror reflected light path. The primary mirror and the tertiary mirror have a same fifth-order polynomial freeform surface expression. The primary mirror reflected light path, the secondary mirror reflected light path and the tertiary mirror reflected light path overlap with each other.

An off-axis three-mirror optical system with freeform surfaces comprised an aperture, a primary mirror, a secondary mirror, a tertiary mirror, and a detector. The aperture is located on an incident light path. The primary mirror is located on an aperture side. The secondary mirror is located on a primary mirror reflected light path. The tertiary mirror is located on a secondary mirror reflected light path. The detector located on a tertiary mirror reflected light path. The primary mirror and the tertiary mirror have a same fifth-order polynomial freeform surface expression. The primary mirror reflected light path, the secondary mirror reflected light path and the tertiary mirror reflected light path overlap with each other.

An off-axial three-mirror optical system with freeform surfaces includes a primary mirror, a secondary mirror, a tertiary mirror, and an image sensor. The primary mirror is located on an incident light path. The secondary mirror is located on a primary mirror reflecting light path. The tertiary mirror is located on a secondary mirror reflecting light path. The image sensor is located on a tertiary mirror reflecting light path. A primary mirror surface and a tertiary mirror surface are all xy polynomial freeform surfaces up to a fifth order. A secondary mirror surface is a planar surface.

A system comprises a sensor subsystem for imaging an object space, and a telescope for coupling electromagnetic energy from the object space to the sensor subsystem. The system comprises a bypass optical path that bypasses the telescope on the way to the sensor subsystem in order to provide a larger field of view of the object space. The bypass path and the telescope path merge at a merging point between the telescope and the sensor subsystem, and are disjoint upstream of the merging point. A simple bypass configuration is therefore provided, with possibly just a single fold mirror at the merging point. A sensor may form an intermediate image, and a frame is placed at the intermediate image to reject stray radiation and provide a real and accessible intermediate pupil for the sensor. Other features are also provided.

Systems and methods of the present disclosure are directed to optics used in absorption cell spectrometers. The absorption cell includes a plurality of mirrors arranged in a manner such that a detection light traverses multiple passes through the fluid within the absorption cell. In some implementations, the detection light is reflected by the plurality of mirrors to form optical paths in more than one plane. In some implementations, the orientation of the mirrors are aligned with specific orientations to provide the desired optical path to the detection light. In one or more embodiments, an alignment apparatus can be used to pre-align the mirrors before they are placed within the absorption cell. The alignment apparatus includes an aperture plate and an adjustable mount to mount one or more mirrors. The mirrors are aligned based on reflected images on the aperture plate laser light incident on the mirrors.

An off-axis three-mirror optical system with freeform surfaces includes a primary mirror, a secondary mirror, a tertiary mirror, and an image sensor. The primary mirror receives light rays first and the secondary mirror is located on a path of light reflected from the primary mirror. The tertiary mirror receives light reflected from the secondary mirror. The image sensor is located on a path of light reflected from the tertiary mirror. Each reflecting surface of the primary and tertiary mirrors is a sixth order xy polynomial freeform surface. The secondary mirror reflecting surface is a spherical surface. A field of view of the off-axis three-mirror optical system with freeform surfaces in Y-axis direction is greater or equal to 65. A field of view of the off-axis three-mirror optical system with freeform surfaces in X-axis direction is greater or equal to 0.8.

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 head-up display using a backlight to control an eyebox, is applicable to being used with an imaging semi-reflective mirror, and includes a backlight source, a switchable adjustment mirror device, a backlight concave mirror, a display panel and an imaging concave mirror. The switchable adjustment mirror device is positioned at the light path between the backlight source and the backlight concave mirror and includes a plurality of mirrors having different curvatures, and each one of the mirrors can be selected to reflect the backlight beam from the backlight source to the backlight concave mirror. Accordingly, the position of the eyebox can be controlled to match with the position of the eyes of the viewer.

A display device includes a display, and displays, using light including infrared light, a high-temperature image portion representing a high-temperature object having a temperature higher than a predetermined temperature in response to an image displayed by the display including the high-temperature image portion. An aerial image display device includes a display including a display surface, and a reflective optical system that reflects image light of an image displayed on the display surface and forms an aerial image as a real image. The aerial image display device displays, using light including infrared light, a high-temperature image portion representing a high-temperature object having a temperature higher than a predetermined temperature on the display surface in response to the image including the high-temperature image portion. The aerial image display device displays the high-temperature image portion as a video.