In this study, a head-mounted display (HMD) system based on a wedge-shaped holographic waveguide that can present holographic virtual images with tunable distance is achieved. The compact computer-generated-hologram system using a spatial light modulator was employed to offer the dynamic image, where the probe beam for the hologram reconstruction is a convergent wave, and the DC term of the diffraction wave can be blocked by a barrier. The wedge-shaped holographic waveguide element was used as the combiner of the HMD system to generate a compact structure. A wedge with a polished surface was designed for in-coupling the image into the waveguide, and a reflection-type holographic optical element (HOE) was used for out-coupling the image from the waveguide. The astigmatism aberration and deformation of the diffraction images at various distances are analyzed and then are compensated. Finally, the virtual image can be obtained without aberration with experimental verification.

In this manuscript, the astigmatism of the waveguide combiner with a pair of symmetry HOEs was analyzed. The light field can be predicted by the modified convolution formulation of Fresnel diffraction when the information of light passes through the astigmatism causing element. Then the astigmatism can be corrected. The theory was experimentally proved by the system with a phase-only SLM and a diffraction planar waveguide. Furthermore, the image quality of astigmatism corrected phase-type CGHs can be improved via the iteration process. Since the coherence of light source was employed, the temporal averaging method was utilized to avoid speckle noise.

We propose what we believe is the first all-optical fiber sensing system without any electronic processing. A multiple-mode fiber detects external perturbations and serves as a random phase generator. A crystal serves as the volume hologram recorder and database and provides the interconnections between a specific incoming random phase and the corresponding output pattern indicating the external perturbation on the fiber. All aspects of the sensing system, including detection of the external perturbation, interconnection, and display of the result, are performed by optical means.

A see-through display based on a planar holographic waveguide with a tunable focal plane is presented. A negative liquid crystal lens is attached on the outcoupling location of the waveguide to manipulate the image distance. The continuous tunable range for the focal length is from negative infinity to −65 cm. The demonstrated prototype system provides 10.5° field-of-view (FOV) for the images not locating at infinity. The FOV for the images not locating at infinity is limited by the diameter of the liquid crystal lens. The lens function of the liquid crystal lens is polarization dependent. By controlling the polarization states of the real scene and the input information image, the liquid crystal lens keeps the see-through function for a real scene and simultaneously plays the role of a negative lens for the input information image. Compared to the see-through display system with a single focal plane, the presented system offers a more comfortable augmented reality (AR) experience.

A distortion aberration (DA) correction device is fabricated using a liquid crystal lens array (LCLA), which is placed at the intermediate image plane of the optical system. Without voltage, the LCLA does not work, the image is distorted due to the aberration from the optical system; with voltage, the incident light is focused by the LCLA and then the distorted image is corrected. The correction of distorted image by LCLA is attributed to the redirection of the off-axis propagated chief ray approaches the principal point of the lens element.

The $+1$ order diffraction of polarization holographic gratings generated by two linear orthogonally polarized writing beams in dye-doped liquid-crystal films were increased by using two recording beams with unequal intensity. The maximum diffraction efficiency of the polarization holograms in our experimental sample can reach 23% when the intensity ratio of two recording beams is 7:1, and this value is almost triple that when the intensity ratio of two recording beams is 1:1.