Disclosed is an ultra-short focus projecting optical system, which includes a display unit, a first lens group having a positive focus power, a second lens group having a positive focus power, a third lens group having a negative focus power, and an aspherical reflector arranged sequentially along a projection direction. The first lens group includes a first lens, a second lens and a diaphragm arranged sequentially along the projection direction. The first lens is a glass aspherical lens, the second lens is a glass spherical lens, and the first lens and the second lens are bent toward the diaphragm from their respective centers to their respective peripheries. The ultra-short focus projecting optical system and a projection device provided by this application can realize a large aperture and high resolution.

Disclosed is an ultra-short focus projecting optical system, which includes a display unit, a first lens group having a positive focus power, a second lens group having a positive focus power, a third lens group having a negative focus power, and an aspherical reflector arranged sequentially along a projection direction. The first lens group includes a first lens, a second lens and a diaphragm arranged sequentially along the projection direction. The first lens is a glass aspherical lens, the second lens is a glass spherical lens, and the first lens and the second lens are bent toward the diaphragm from their respective centers to their respective peripheries. The ultra-short focus projecting optical system and a projection device provided by this application can realize a large aperture and high resolution.

An optical imaging assembly is provided, having an optical axis; an object axis defined by an object being imaged; an aperture stop disposed on the optical axis; a light-transmissive sleeve enclosing the object axis, being disposed in object space defined by the object axis; and at least three refractive lens elements being arranged between the object and the aperture stop without any other intervening optical component, at least one of the elements having surfaces having at least one of cylindrical and acylindrical prescription, with an image plane, wherein the object being imaged lies within the sleeve.

The present disclosure discloses an imaging apparatus and an electronic device. The imaging apparatus includes a macro lens group, a wide-angle lens group, and a telephoto lens group. An effective focal length f.sub.A of the macro lens group, an effective focal length f.sub.B of the wide-angle lens group and an effective focal length f.sub.C of the telephoto lens group satisfy: f.sub.A<f.sub.B<f.sub.C, 0.20<f.sub.A/f.sub.B<0.80 and 0.10<f.sub.A/f.sub.C<0.50.

A lens system (10) for image pickup includes, in order from an object side (11), a first lens group (G1) that has negative refractive power and is fixed during focusing, a second lens group (G2) that has positive refractive power and moves during focusing, a third lens group (G3) that has positive refractive power and is fixed during focusing, and a fourth lens group (G4) that has a stop disposed on the object side, is disposed closest to an image plane side, has positive refractive power, and is fixed during focusing. The first lens group includes a first lens (L11) with positive refractive power that is disposed closest to the object side.

An exposure device for recording a hologram. The exposure device includes at least one modulation unit, which is designed to generate a modulation beam representing a reference beam and/or an object beam by impressing a modulation representing at least one holographic element of the hologram onto a laser beam. The exposure device also includes at least one reduction unit, which is designed to generate a modified modulation beam using the modulation beam, the modified modulation beam having a smaller beam diameter than the modulation beam. The exposure device further includes at least one objective lens unit, which is designed to direct the modified modulation beam through an immersion medium onto a recording material in order to record the hologram by exposing the recording material to the modified modulation beam.

A lens assembly may include: a first lens having positive refractive power and including a convex subject side surface; a second lens; a third lens having negative refractive power and including a subject side surface being convex toward an image secsor side in a center portion thereof, through which an optical axis passes; a fourth lens having positive or negative refractive power; and a fifth lens having positive or negative refractive power. The first lens, the second lens, the third lens, the fourth lens, and the fifth lens may be sequentially arranged from a subject to an image sensor along the optical axis. The lens assembly may satisfy a condition defined by 0.6<TTL/ImgH<1, where “TTL” represents a distance from the subject side surface of the first lens to an imaging surface of the image sensor, and “ImgH” represents a maximum image height of an image formed on the imaging surface.

An optical imaging lens assembly, which is applied for an endoscopic optical device, from an object side to an image side aligned in order includes a first lens element, a second lens element and a third lens element. The first lens element has negative refracting power, and further has a first convex object-side surface and a first image-side surface. The second lens element has positive refracting power, and further has a second convex object-side surface and a second concave image-side surface. The third lens element has positive refracting power, and further has a third convex image-side surface and a third object-side surface.

A system includes a head-mounted display (HMD) device configured to project digital images to a user's eye and a viewing device. The viewing device includes an optical relay unit having a world-facing surface and an eye-facing surface and a holder coupled to the optical relay unit and configured to support the HMD device near the world-facing surface. The optical relay unit is configured to transmit light projected by the HMD device to an eye-facing aperture disposed at the eye-facing surface of the optical relay. The system shifts an eyebox of the HMD by receiving light projected from an optical combiner of the HMD, transmitting the light through the optical relay unit of the viewing device to the eye-facing aperture of the optical relay unit, and outputting the light from the eye-facing aperture such that the light is focused at an eyebox in which a user's eye is located.

A system includes a head-mounted display (HMD) device configured to project digital images to a user's eye and a viewing device. The viewing device includes an optical relay unit having a world-facing surface and an eye-facing surface and a holder coupled to the optical relay unit and configured to support the HMD device near the world-facing surface. The optical relay unit is configured to transmit light projected by the HMD device to an eye-facing aperture disposed at the eye-facing surface of the optical relay. The system shifts an eyebox of the HMD by receiving light projected from an optical combiner of the HMD, transmitting the light through the optical relay unit of the viewing device to the eye-facing aperture of the optical relay unit, and outputting the light from the eye-facing aperture such that the light is focused at an eyebox in which a user's eye is located.