A substrate-guided holographic diffuser has a light-guide section configured to in-couple light and transmit the light within itself via total internal reflection. It can also have a brightness enhancement section that recycles non-diffracted light within the light-guide section. A hologram section that receives light from the light-guide section has a holographic structure defining acceptance conditions and is positioned relative to the internally reflected light such that the internally reflected light meets the acceptance conditions of the holographic structure. The internally reflected light is out-coupled by the holographic structure as a projected image of light scattered from a diffuser.

A holographic image film, and a holographic image recording method and reconstruction method are provided. The holographic image recording method includes a preparation step, an irradiation step and a recording step. The preparation step includes stacking a holographic negative film on a transparent substrate. The irradiation step includes emitting object light and reference light. The reference light is emitted into the transparent substrate and undergoes multiple times of total reflections in a thickness of the transparent substrate to form total internal reflected light. The recording step includes generating a holographic image interference line by a mutual interference between the total internal reflected light and the object light, and recording the holographic image interference line on the holographic negative film in a photosensitive manner.

Multiple pairs of substrate-guided wave-based holograms (SGWHs) are laminated to a common thin substrate to form a transparent substrate-guided wave-based holographic CHMSL (SGWHC) that diffracts playback LED illumination over a wide angular range. This device is made pursuant to a technique that includes the steps of recording a first set of SGWHs with one setup, that upon playback, will couple and guide the diffracted light inside the substrate, and a second set of SGWHs recorded with another setup, that will diffract and couple the guided light out.

A substrate-guided holographic diffuser has a light-guide section configured to in-couple light and transmit the light within itself via total internal reflection. It can also have a brightness enhancement section that recycles non-diffracted light within the light-guide section. A hologram section that receives light from the light-guide section has a holographic structure defining acceptance conditions and is positioned relative to the internally reflected light such that the internally reflected light meets the acceptance conditions of the holographic structure. The internally reflected light is out-coupled by the holographic structure as a projected image of light scattered from a diffuser.

Energy relays may be formed to have various surface profiles. Methods and devices are disclosed for forming energy relays with energy propagation paths configured to account for various energy relay surface profiles so that the energy relays can direct energy through the surfaces of the energy relays with the desired angular profiles and angular extent.

VHOEs with expanded acceptance angle ranges are described as well as various systems and methods for fabricating VHOEs with expanded acceptance angle ranges. The VHOE with expanded acceptance angle range may include two or more individual Bragg gratings. The two or more individual Bragg gratings have the same diffraction geometry but with shifted Bragg conditions. Having the same diffraction geometry means when light is incident on the VHOE including two or more individual Bragg gratings, the diffracted light from each of the Bragg gratings is co-linear or overlapping with the diffracted light from the other Bragg gratings. The Bragg condition for each of the Bragg gratings are shifted with respect to each neighboring Bragg grating by an amount up to the acceptance angle range of each individual Bragg grating.

A lensless holographic imaging system having a holographic optical element includes: a coherent light source for outputting a first light beam and a second light beam, wherein the first light beam irradiates a first inspection plane to form first object-diffracted light; a light modulator for modulating the second light beam into reading light having a specific wavefront; a multiplexed holographic optical element, wherein the first object-diffracted light passes through the multiplexed holographic optical element, and the reading light is input into the multiplexed holographic optical element to generate a diffracted light beam as system reference light; and an image capture device for reading at least one interference signal generated by interference between the first object-diffracted light and the system reference light. The lensless holographic imaging system has a relatively small volume and relatively high diffraction efficiency.

A digital holographic image-taking apparatus includes an illumination portion having a light emission surface for emitting illumination light toward an object, the illumination light having a specific wavelength in a coherent plane waveform; and an image sensor having an pixel array including two-dimensionally arranged pixels, the image sensor capturing an interference pattern generated based on the illumination light having acted on the object, in which the following conditional expression is satisfied: 0.0000001<Z.sup.2/S<16, where S represents the area of the light emission surface, and Z represents the distance from the light emission surface to the pixel array.

A method of manufacturing a holographic element used in a projection device is provided. The projection device has a light source configured to emit light conforming to a non-uniform light intensity distribution function. The method includes: multiplying the non-uniform light intensity distribution function by a diffraction intensity and angle function of a grating to obtain a product function; determining whether the product function is substantially equal to 1 in a predetermined range of angle or wavelength; if the the determination result is yes, determining a pair of incident angles respectively of a reference beam and a signal beam according to the diffraction intensity and angle function; and recording a holographic material with the reference beam and the signal beam respectively at the pair of incident angles, so as to manufacture a holographic element with the grating therein.

Multiple pairs of substrate-guided wave-based holograms (SGWHs) are laminated to a common thin substrate to form a transparent substrate-guided wave-based holographic CHMSL (SGWHC) that diffracts playback LED illumination over a wide angular range. This device is made pursuant to a technique that includes the steps of recording a first set of SGWHs with one setup, that upon playback, will couple and guide the diffracted light inside the substrate, and a second set of SGWHs recorded with another setup, that will diffract and couple the guided light out.