Examples are disclosed that relate to a compact optical systems comprising SLMs. One example provides a projection system comprising an illumination stage including a light emitting diode (LED) array. The LED array comprises a plurality of red LEDs, a plurality of green LEDs, and a plurality of blue LEDs. The illumination stage further comprises an illumination stage optical system configured to control an angular extent of light emitted by the LED array and homogenize the light emitted by the LED array. The projection system further comprises an image forming stage configured to form an image from light output by the illumination stage, the image forming stage comprising a spatial light modulator (SLM) configured to spatially modulate the light output by the illumination stage to form an image, and one or more projection optics configured to project the image formed by the spatial light modulator.

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 Δn 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 θ.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.

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.

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 Δn 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 θ.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.

Unidirectional grating-based backlighting includes a light guide and a diffraction grating at a surface of the light guide. The light guide is to guide a light beam and the diffraction grating is configured to couple out a portion of the guided light beam using diffractive coupling and to direct the coupled-out portion away from the light guide as a primary light beam at a principal angular direction. The diffraction grating is to further produce a secondary light beam directed into the light guide at an opposite one of the principal angular direction. The unidirectional grating-based backlighting further includes an angularly selective reflective layer within the light guide adjacent to the light guide surface that is configured to reflectively redirect the diffractively produced, secondary light beam out of the light guide in the direction of the primary light beam.

An augmented reality device is provided and comprises a waveguide (306); an input diffractive optical element (301) positioned in or on the waveguide (306) configured to receive light from a projector and to couple the light into the waveguide (306) so that it is captured within the waveguide (306) by total internal reflection; an output diffractive optical element (304) positioned in or on the waveguide (306) configured to couple totally internally reflected light out of the waveguide (306) towards a viewer; and a returning diffractive optical element (307, 309, 312) positioned in or on the waveguide (306) configured to receive light from the output diffractive optical element (304) and to diffract the received light so that it is returned towards the output diffractive optical element (304).

An opto-electronic system includes a laser operable to produce a laser beam; an optical element including two or more beam-shaping portions, each of the two or more beam-shaping portions having a different optical property; a beam deflector arranged to sweep the laser beam across the optical element to produce output light; and electronics communicatively coupled with the laser, the beam deflector, or both the laser and the beam deflector. The electronics are configured to cause selective impingement of the laser beam onto a proper subset of the two or more beam-shaping portions of the optical element to modify one or more optical parameters of the output light.

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.

An exposure apparatus includes an illumination optical system for illuminating an original including a periodic pattern, a projection optical system for forming an image of the original on a substrate, a controller configured to cause light from the illumination optical system to be obliquely incident on the original such that a light intensity distribution which is line-symmetric with respect to a line, passing through an origin of a pupil region of the projection optical system and orthogonal to a periodic direction of the periodic pattern, is formed in the pupil region by diffracted light beams including diffracted light of not lower than 2nd-order from the periodic pattern, and to control exposure of the substrate such that each point in a shot region of the substrate is exposed in not less than two focus states.

An apparatus for intraoral scanning includes an elongate handheld wand that has a probe. One or more light projectors and two or more cameras are disposed within the probe. The light projectors each has a pattern generating optical element, which may use diffraction or refraction to form a light pattern. Each camera may be configured to focus between 1 mm and 30 mm from a lens that is farthest from the camera sensor. Other applications are also described.