A wearable heads-up display includes a power source, laser sources, and a lightguide. A photodetector is positioned to detect an intensity of a test light emitted at a perimeter of the lightguide from an optical path within the lightguide. A laser safety circuit provides a control to reduce or shut off a supply of electrical power from the power source to the laser sources in response to an output signal from the photodetector indicating that the detected intensity is below a threshold.

A light-guiding plate includes a resin base having a parallelism P of 5 μm or less per an area of 50×100 mm.sup.2.

A diffractive optical waveguide is provided, which comprises a waveguide substrate and a coupling-in grating, a coupling-out grating, and a coupling-in end light-return grating formed on the substrate, the coupling-in grating couples an input beam into the waveguide substrate and forms a first beam of light propagating toward the coupling-out grating and a second beam of light not propagating toward the coupling-out grating, the coupling-out grating couples at least a part of the light propagating therein out of the substrate, and the coupling-in end light-return grating diffracts the second beam of light so that it propagates toward the coupling-out grating. A display device having the above diffractive optical waveguide is also disclosed. By providing the coupling-in end light-return grating, optical coupling efficiency of the diffractive optical waveguide is improved, and the energy distribution uniformity of an output field of the diffractive optical waveguide is improved.

Diffraction gratings provide optical elements in head-mounted display systems to, e.g., incouple light into or out-couple light out of a waveguide. These diffraction gratings may be configured to have reduced polarization sensitivity. Such gratings may, for example, incouple or outcouple light of different polarizations with similar level of efficiency. The diffraction gratings and waveguides may include a transmissive layer and a metal layer. The diffraction grating may comprises a blazed grating.

In a display device, an image having an aspect not equal to 1 is formed by an image forming unit configured to form an image, and the image is guided as an image light to a display position by an optical system. The optical system, which is provided with a diffraction optical element, deflects the image light. In the diffraction optical element, a pitch direction of a pattern for deflecting the image light coincides with a direction in which the aspect of the image is narrow. In the display device, the direction in which the image light is deflected by the diffraction optical element coincides with the direction in which the aspect of the image formed is narrow, thus making it possible to suppress unevenness of brightness and hue within a plane of an image displayed.

An optical system for transmitting a source image includes a light guide, which defines a light transmission channel, an optical coupling arrangement and an optical decoupling arrangement, the coupling arrangement being designed to couple light emerging from the source image into the light guide arrangement in such a way that the light can propagate in the light guide arrangement by total reflection, and the decoupling arrangement being designed to decouple light that has propagated in the light guide arrangement from the light guide arrangement. The light guide arrangement comprises an optical deflection device, which, as viewed in the direction of propagation of the light in the light guide arrangement, is arranged between the coupling arrangement and the decoupling arrangement and is designed to deflect light ray bundles, emerging from the coupling arrangement at different beam angles and impinging divergently on the deflection device, in bundled manner towards the decoupling arrangement.

An optical filter, a spectrometer including the optical filter, and an electronic apparatus including the optical filter are disclosed. The optical filter includes a first reflector including a plurality of first structures that are periodically two-dimensionally arranged, each of the first structures having a ring shape, and a second reflector spaced apart from the first reflector and including a plurality of second structures that are periodically two-dimensionally arranged.

An optical element may include a substrate. The optical element may include a first anti-reflectance structure for a particular wavelength range formed on the substrate. The optical element may include at least one layer disposed on a portion of the first anti-reflectance structure. The optical element may include a second anti-reflectance structure for the particular wavelength range formed on the at least one layer. A depth between a first surface of the first anti-reflectance structure and a second surface of the second anti-reflectance structure, a first index of refraction of the first anti-reflectance structure, a second index of refraction of the second anti-reflectance structure, and a third index of refraction of the at least one layer may be selected to form a diffractive optical element associated with a particular phase delay for the particular wavelength.

A projector assembly includes three coaxially aligned lenses and an aperture stop. The three coaxially aligned lenses include a first lens and, in order of increasing distance therefrom and on a same side thereof, a second lens and a positive meniscus lens. The first lens is a positive lens. The second lens is a negative lens. The second lens is located between the aperture stop and the positive meniscus lens. The projector assembly is one-sided telecentric at a plane proximate the positive meniscus lens.

A waveguide display assembly comprises a waveguide, including an in-coupling grating configured to in-couple light of a first wavelength band emitted by a light source into the waveguide, and cause propagation of the light of the first wavelength band through the waveguide via total internal reflection. An out-coupling grating is configured to out-couple the light of the first wavelength band from the waveguide and toward a user eye. One or more diffractive gratings are disposed along an optical path between the in-coupling grating and the out-coupling grating, the one or more diffractive gratings configured to diffract light outside the first wavelength band out of the waveguide and away from the user eye.