An off-axis optical system having a rectangular aperture stop to control rays of incident electromagnetic radiation passing through the optical system along an optical path is provided. The optical system includes one or more optical surfaces along the optical path, each surface being configured to change a direction of each ray on the surface based on a location of the ray relative to the surface. At least one of the surfaces is conjugate to and has the same shape as the rectangular aperture stop. In one embodiment, each optical surface is shaped to avoid vignetting the rays. In one embodiment, the optical system is a three-mirror anastigmat (TMA) and includes a concave primary mirror to collect and focus the electromagnetic radiation; a curved secondary mirror to reflect the electromagnetic radiation focused by the primary mirror; and a concave tertiary mirror to focus the electromagnetic radiation reflected by the secondary mirror.

An off-axis optical system having a rectangular aperture stop to control rays of incident electromagnetic radiation passing through the optical system along an optical path is provided. The optical system includes one or more optical surfaces along the optical path, each surface being configured to change a direction of each ray on the surface based on a location of the ray relative to the surface. At least one of the surfaces is conjugate to and has the same shape as the rectangular aperture stop. In one embodiment, each optical surface is shaped to avoid vignetting the rays. In one embodiment, the optical system is a three-mirror anastigmat (TMA) and includes a concave primary mirror to collect and focus the electromagnetic radiation; a curved secondary mirror to reflect the electromagnetic radiation focused by the primary mirror; and a concave tertiary mirror to focus the electromagnetic radiation reflected by the secondary mirror.

Reflective imager sub-systems that have a non-circular entrance pupil and provide substantially increased throughput to a detecting component of a system are disclosed.

A light irradiation apparatus that splits white light into light rays of a plurality of wavelengths to apply the light ray includes a white light source, a diffraction grating that splits white light emitted by the white light source into light rays of a plurality of wavelengths, and a light selector that selects a light ray of a specified wavelength from the light rays of the plurality of wavelengths split by the diffraction grating.

In order to provide a multireflection cell making it possible to decrease the volume of a cell main body into which measurement target gas is introduced as well as reducing the amount of light that is lost without being reflected in a multireflection mechanism, the multireflection cell includes the multireflection mechanism adapted to multiply reflect incident light and then emit the multiply reflected light outward. In addition the multireflection mechanism includes a field mirror, a first objective mirror that faces to the field mirror and is provided on a light incident side in the multireflection mechanism, and a second objective mirror that faces to the field mirror and is provided on a light emitting side in the multireflection mechanism. Further, the light incident into the multireflection mechanism is configured to be first reflected by the second objective mirror.

In order to provide a multireflection cell making it possible to decrease the volume of a cell main body into which measurement target gas is introduced as well as reducing the amount of light that is lost without being reflected in a multireflection mechanism, the multireflection cell includes the multireflection mechanism adapted to multiply reflect incident light and then emit the multiply reflected light outward. In addition the multireflection mechanism includes a field mirror, a first objective mirror that faces to the field mirror and is provided on a light incident side in the multireflection mechanism, and a second objective mirror that faces to the field mirror and is provided on a light emitting side in the multireflection mechanism. Further, the light incident into the multireflection mechanism is configured to be first reflected by the second objective mirror.

An optical system comprising includes an off-axis folded three mirror anastigmat (TMA) telescope including a primary mirror for receiving energy from a scene. A secondary mirror is aligned to receive reflected energy from the primary mirror. A fold mirror is aligned to receive reflected energy from the secondary mirror. A tertiary mirror is aligned to receive reflected energy from the fold mirror and to direct energy between the secondary mirror and the fold mirror. A beam splitter is aligned to receive energy reflected from the tertiary mirror, to reflect a portion of that energy to a first imaging sensor, and to pass a second portion of that energy to a second imaging sensor.

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.

Disclosed embodiments enable scaling of monolithic optical systems (e.g., monolith telescopes) up to larger aperture sizes while reducing mass scaling. An example optical system includes a monolithic mirror assembly that integrates a primary mirror and a tertiary mirror in static alignment. The optical system further includes a secondary mirror or fold mirror displaced away from the monolithic mirror assembly and having a reflective mirror surface. The secondary mirror's reflective mirror surface is positioned to direct light received from the primary mirror onto the tertiary mirror and direct light received from the tertiary mirror onto a detector. The secondary mirror is particularly configured to maintain a low alignment sensitivity, consistent with the permanent fixed alignment associated with the monolithic mirror assembly. For example, the secondary mirror has a relatively low power curvature and a weak fourth-order shape insensitive to decentering and tip/tilt misalignments when directing light onto the spherical tertiary mirror.

A snapshot spatial dimension spectral polarization integrated imaging system and a design method thereof are provided. An objective lens generate an image of a target on a DMD; the DMD is disposed on a focal plane of the objective lens and connected to the computer; the computer controls an encoding matrix loaded on the DMD to encode information; the light is reflected to the primary mirror after being encoded, and then is reflected by the primary mirror to the convex grating for dispersion; the light is then reflected to the third mirror; an encoded image is produced on the micro polarizer array detector; polarization channel coding is completed; the micro polarizer array detector is connected to the computer; and the computer resolves compressive spectral polarization image based on spectral polarization coding data cube obtained on a target surface of the micro polarizer array detector.