An observation optical system according to the present invention includes a reflective optical device (30), a first lens group (10), and a second lens group (20). The reflective optical device (30) includes at least one reflection surface (31). The first lens group (10) is disposed at a position closer to an entrance pupil (E.P.) than the reflective optical device (30). The first lens group (10) forms an intermediate image (40) of a virtual image on the reflection surface (31) or at a position closer to the entrance pupil (E.P.) than the reflection surface (31). The intermediate image (40) of the virtual image corresponds to an image displayed on an image display unit (2). The second lens group (20) is disposed on an optical path after light passes through the first lens group (10), the intermediate image (40), and the reflective optical device (30) in order in a case where ray tracing is performed from an entrance pupil (E.P.) side. The second lens group (20) is disposed to cause an image (50) of the entrance pupil (E.P.) to be formed on an optical path after light is reflected by the reflection surface (31).

An imaging system, including a light valve, a projection surface, 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 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.

A virtual image display apparatus includes a display device (image forming unit), a lens configured to refract imaging light from the display device, a first mirror member configured to reflect imaging light that passed through the lens, a second mirror member configured to reflect the imaging light reflected by the first mirror member, and a third mirror member of a transmissive type configured to reflect the imaging light reflected by the second mirror member toward a position of an exit pupil. The lens is asymmetric with respect to an optical axis in a first direction corresponding to an eccentric direction defined by the first mirror member and the second mirror member, and is symmetric, across the optical axis, with respect to a second direction orthogonal to the first direction.

Devices, systems and methods related to all-reflective microscopes are described. The microscopes include an all-reflective off-axis optical system and is characterized with substantially zero chromatic aberration, low group delay dispersion and no central obscuration. One reflective microscope configuration includes a reflective objective subsection with at least three mirrors, where at least one mirror is off-axis and non-spherical. The reflective microscope also includes a reflective relay subsection with at least two minors having freeform surfaces and positioned to receive light from the reflective objective subsection. The reflective relay subsystem is configured to produce a magnification to allow coupling of light between two planes having differing beam sizes. The reflective microscope further includes an imaging subsection with at least one mirror having a freeform surface and positioned to receive light from the reflective relay subsection and to direct light received thereon in reflection in a direction of a sensor.

Provided by the present invention relates to the field of optical technology and is a symmetric imaging plane free-form surface optical system having a two-dimensional large field of view comprising a first reflector, a second reflector, a third reflector, a fourth reflector and a detector imaging plane which are arranged along a light path direction in sequence, and further comprising an aperture stop, wherein a position wherein the aperture stop is located at is overlapped with a position wherein the second reflector is located at such that a light beam is allowed to be reflected by the first reflector to the second reflector, after reflected by the second reflector then is injected to the third reflector, after reflected by the third reflector then is injected to the fourth reflector, after reflected by the fourth reflector then is injected to the imaging surface of the detector for imaging.

A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.

A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.

A stop, such as a numerical aperture stop, obscuration stop or false-light stop, for a lithography apparatus, includes a light-transmissive aperture and a stop element, in which or at which the aperture is provided. The stop element is opaque and fluid-permeable outside the aperture.

A display device according to the present invention includes, along an optical path of image light emitted from an image light generating device, a first optical unit having positive power, a second optical unit having positive power and including a first diffraction element of a reflective type, a third optical unit having positive power, and a fourth optical unit having positive power and including a second diffraction element of a reflective type. The second optical unit includes a first light-transmitting member having optical power and provided at a first surface of the first diffraction element, and a light shielding member provided at a second surface of the first diffraction element.

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.