A diffractive optical element includes: a substrate; a protrusion and recess portion that is formed on one surface of the substrate and imposes predetermined diffraction on incident light; and an antireflection layer provided between the substrate and the protrusion and recess portion. An effective refractive index difference n in a wavelength range of the incident light between a first medium constituting a protrusion of the protrusion and recess portion and a second medium constituting a recess of the protrusion and recess portion is 0.70 or more. An exit angle range .sub.out of diffraction light exiting from the protrusion and recess portion when the incident light enters the substrate from a normal direction of the substrate is 60 or more. Total efficiency of diffraction light exiting from the protrusion and recess portion in the exit angle range is 65% or more.

The present invention provides a projector, wherein the projector includes a light-emitting device, a lens module having a diffuser part and a lens part, and a DOE. In the operations of the projector, the light-emitting device is arranged for generating at least one laser beam, and the at least one laser beam passes through the diffuser part and the DOE to illuminate a field of view, and the at least one laser beam passes through the lens part and the DOE to generate a plurality of dots.

A near-eye-display (NED) includes a tracking system and a waveguide assembly. The waveguide assembly includes an infrared (IR) light source and an output waveguide. The output waveguide includes at least a decoupling element that outcouples the IR light emitted by the IR light source to form the structured light pattern. The structured light pattern is projected toward one or more regions of a user's face, for example, the user's eyes. The structured light pattern is reflected off the one or more regions of the user's face and captured by the tracking system. The tracking system can determine tracking information such as eye tracking information as well as face tracking information based on the captured reflected structured light pattern.

A display apparatus for displaying a virtual image (VIMG1) includes a rotating expander device (EPE1) to form light beams (B3.sub.P0,R,B3.sub.P1,R) of output light (OUT1) by expanding light beams (B0.sub.P0,R,B0.sub.P1,R) of input light (IN1), the expander device (EPE1) includes: a waveguide plate (SUB1), an in-coupling element (DOE1) to form first guided light (B1a) and second guided light (B1c) by coupling input light (IN1) into the waveguide plate (SUB1), a first out-coupling element (DOE3a) to form output light (OUT1) by coupling the first guided light (B1a) out of the waveguide plate (SUB1), and a second out-coupling element (DOE3c) to form output light (OUT1) by coupling the second guided light (B1c) out of the waveguide plate (SUB1). The in-coupling element (DOE1) has a first input grating vector (V.sub.1a) and a second input grating vector (V.sub.1c), and an angle (.sub.1ac) between the first and second input grating vectors is between 60 and 120.

An image display apparatus of the present invention includes: a beam emitting section (10) that radially emits a plurality of beams (Ls1 to Ls5) in a horizontal direction; a mirror rotary member (20) having a rotation axis (Pc) and an inner surface, the inner surface having a plurality of mirror surfaces (21) that reflects each of the plurality of beams (Ls1 to Ls5), the mirror rotary member as a whole rotating about the rotation axis (Pc) as a center to thereby perform, by the plurality of mirror surfaces (21), scanning with each of the plurality of beams (Ls1 to Ls5) emitted from the beam emitting section (10) in the horizontal direction; and a screen (2) to be irradiated with the plurality of beams (Ls1 to Ls5) with which the scanning is performed by the plurality of mirror surfaces (21).

To protect observer's eyes while forming a clear illumination pattern on a desired region to be illuminated. An illumination device includes a light source that emits coherent light, a collimating optical system that enlarges and collimates a beam diameter of the coherent light emitted from the light source, and a diffractive optical element that diffracts the coherent light collimated by the collimating optical system into a predetermined diffusion angle space. The diffractive optical element has a plurality of element diffractive optical portions and has a function to illuminate the region to be illuminated defined at a predetermined position and having predetermined size and shape to form the desired illumination pattern. Each of the plurality of element diffractive optical portions has a function to illuminate at least a part of the region to be illuminated, and diffractive characteristics of the element diffractive optical portions are different from each other.

An alignment system aligns a laser beam to a desired position in a reference plane and to a desired direction in the reference plane. The system diffracts the laser light into different diffraction orders that are projected onto a detection plane using different lenses. As the locations of the projections of the different diffraction orders in the detection plane respond differently to changes in position and in direction of the beam in the reference plane, the locations of the projections enable to determine how to adjust the beam so as to get the beam properly aligned. The diffraction and the projection can be implemented by a hologram.

A diffractive optical element is configured to provide desired diffracted light and is excellent in durability. The diffractive optical element shapes light from a light source, wherein the diffractive optical element is provided with a diffractive layer having a periodic structure having low refractive index portions and high refractive index portions, and the high refractive index portions of the periodic structure include one having an aspect ratio of 2 or more.

The present disclosure discloses a structured light projector, a three-dimensional camera module and a terminal device. The structured light projector includes a light source array, configured to emit at least two light beams; a lens array, configured to collimate the at least two light beams emitted by the light source array to obtain at least two collimated independent coherent light beams; and a diffraction optical element array, configured to modulate the at least two collimated independent coherent light beams to obtain at least two diffracted light beams. By means of the present disclosure, a length of a light path between the light source array and the lens array can be reduced, and therefore a height of the structured light projector can be reduced, so that a lightweight and thin structured light projector can be developed.

An optical lens includes five aspheric lenses and an aperture stop. The five aspheric lenses are, arranged in order from a first side to a second side, a first lens, a second lens, a third lens, a fourth lens and a fifth lens, and the aperture stop is disposed between the first lens and the second lens. An image height at the image plane is denoted as H, the image height is equally divided into ten sections to from ten height positions 0.1H, 0.2H, 0.3H, 0.4H, 0.5H, 0.6H, 0.7H, 0.8H, 0.9H and 1H. Chief rays traveling through the optical lens and to the ten height positions respectively form ten angles with respect to a normal of an image plane, and each of the ten angles is smaller than 10 degrees.