A system is provided. The system includes a light source configured to emit an infrared light to illuminate an eye of a user. The system includes a grating disposed facing the eye and including a birefringent material film configured with a uniform birefringence lower than or equal to 0.1. The grating is configured to diffract the infrared light reflected from the eye, and transmit a visible light from a real world environment toward the eye, with a diffraction efficiency less than a predetermined threshold. The system includes an optical sensor configured to receive the diffracted infrared light and generate an image of the eye based on the diffracted infrared light.

Embodiments of the present disclosure provide an imaging device for holographic imaging of a sample, the imaging device comprising a light source generating a light beam, a beam splitter splitting the light beam into an object beam along an object beam path and a reference beam along a reference beam path, and a detector. The imaging device defines a sample position. The object beam is propagated through the sample position, and the detector is arranged to prevent non-scattered object light, passing through the sample position without being scattered by the sample, from being incident onto the detector. The reference beam is propagated through the sample position, and the detector is arranged so that non-scattered reference light, passing through the sample position without being scattered by the sample, is incident onto the detector. The detector detects an interference pattern formed by scattered object light and the non-scattered reference light.

A generation method of a digital hologram includes steps of emitting coherent light from a coherent light source, imaging a hologram that is an interference pattern of an object beam and a reference beam due to the emission light from the light source, and setting a plurality of wavelengths of the illumination light that generates the hologram detected by the detector, and wherein the plurality of wavelength are specified by the wavelength setting step based on a magnification percentage X of a conjugate image set up by a user not to disturb visibility of an image when a real image and the conjugate image reconstructed by a predetermined calculation means relative to structures of observation targets are superimposed to a corresponding real image so that a shortest wavelength λ.sub.min and a longest wavelength λ.sub.max satisfy the expression λ.sub.max/λ.sub.min≧(1/X+1).

A system includes a laser emitting a laser beam, a beam expander expanding the laser beam, a beam splitter prism splitting the expanded laser beam into first and second split light beams, a liquid crystal box containing polymer-dispersed liquid crystal, first and second reflectors reflecting the first and second split light beams to the liquid crystal box, respectively, and an attenuator arranged on an optical path between the beam expander and the liquid crystal box. The attenuator gradually attenuates at least one of the laser beam, the expanded laser beam, the first split light beam, or the second split light beam along a first set curve. The first split light beam and the second split light beam form interference fringes at the liquid crystal box to expose the polymer-dispersed liquid crystal to form a polymer-dispersed liquid crystal holographic grating having a diffraction efficiency decreasing along a second set curve.

The layered generation of at least one volume grating in a recording medium by way of exposure, the recording medium having at least one photosensitive layer which is sensitized for a presettable wavelength of the exposure light. Each volume grating is generated in the recording medium by at least two wave fronts of coherent light capable of generating interference, the wave fronts being superposed in the recording medium at a presettable depth, at a presettable angle and with a presettable interference contrast. The depth and the thickness of the refractive index modulation and/or transparency modulation of a volume grating in the recording medium is controlled by depth-specific control of the spatial and/or temporal degree of coherence of the interfering wave fronts in the direction of light propagation.

Holographic optical elements for augmented reality (AR) devices and methods of manufacturing and using the same are disclosed. A disclosed system includes a holographic optical element (HOE), and a first light source to direct a first beam of light toward the HOE from a first direction. The first beam of light is collimated. The disclosed system further includes a second light source to direct a second beam of light toward the HOE from a second direction. The disclosed system also includes a decollimation lens positioned between the first light source and the HOE. The decollimation lens is to decollimate the first beam of light.

In situ investigation of microbial life in extreme environments can be carried out with microscopes capable of imaging 3-dimensional volumes and tracking particle motion. A lensless digital holographic microscope is disclosed that provides roughly 1.5 micron resolution in a compact, robust package suitable for remote deployment. High resolution is achieved by generating high numerical-aperture input beams with radial gradient-index rod lenses. The ability to detect and track prokaryotes was explored using bacterial strains of two different sizes. In the larger strain, a variety of motions were seen, while the smaller strain was used to demonstrate a detection capability down to micron scales.

A device for determining a 3D structure of an object having first and second laser emitters which generate laser radiation with first and second different wavelengths, respectively. A first beam splitter splits the laser radiation of each laser emitter into reference and illuminating radiation. The illuminating radiation is adapted to impinge on the object to be measured, be reflected by the object as object radiation, and interfere with the reference radiation to form interference patterns. A detector receives the interference patterns. A selection hologram deflects object radiation which impinges on it within a predefined incidence angle range and passes object radiation which impinges on it outside of the incidence angle range undiffracted. The undiffracted radiation either passes by the determination area of the detector or impinges on the determination area at an angle outside the determination angle range.

A hologram recording device includes a light outputting unit, which sequentially outputs laser beams having different wavelengths such that the laser beams are coaxial and includes an optical member and laser beam sources, and a recording unit, which sequentially irradiates the recording medium with the laser beams to record holograms in a multiwavelength superimposing manner. The optical member includes optical elements that reflect, in the optical direction, a laser beam incident thereon in a direction crossing the optical axis direction, and that allow a laser beam incident thereon in the optical axis direction to pass therethrough. The laser beam sources radiate laser beams to the optical member, and are arranged so that a laser beam emitted from a laser beam source among the laser beam sources that exposes a recording medium for a longer exposure period with the laser beam passes through a smaller number of optical elements.

A holographic characterization and playback apparatus is provided, which includes a light source, an optical path-forming optical system for separating the light emitted from the light source into a probe light and a reference light of different polarizations, and combining optical paths of the probe light and the reference light.