Recently developed integral imaging techniques are reviewed. Integral imaging captures and reproduces the light rays from the object space, enabling the acquisition and the display of the three-dimensional information of the object in an efficient way. Continuous effort on integral imaging has been improving the performance of the capture and display process in various aspects, including distortion, resolution, viewing angle, and depth range. Digital data processing of the captured light rays can now visualize the three-dimensional structure of the object with a high degree of freedom and enhanced quality. This recent progress is of high interest for both industrial applications and academic research.

A novel system of optical see-through augmented reality (AR) is proposed by making use of a holographic optical element (HOE) with full-color and lens-array functions. The full-color lens-array HOE provides see-through property with three-dimensional (3D) virtual images, for it functions as a conventional lens array only for Bragg-matched lights. An HOE recording setup was built, and it recorded a $30\mathrm{mm}\times 60\mathrm{mm}$ sized full-color lens-array HOE by using the techniques of spatial multiplexing for large-area recording and wavelength multiplexing for full-color imaging. The experimental results confirm that the suggested full-color lens-array HOE can provide the full-color 3D virtual images in the optical see-through AR system.

Despite steady technological progress, displays are still subject to inherent limitations in resolution improvement and pixel miniaturization because a series of colours is generally expressed by a combination of at least three primary colour pixels. Here we propose a structure comprising a metal cavity and a nanoaperture, which we refer to as a cavity-aperture, to simultaneously control the colour and intensity of transmitted light in a single pixel. The metal cavity constructs plasmonic standing waves to organize the spatial distribution of amplitudes according to wavelength, and the nanoaperture permits light with a specific wavelength and amplitude to pass through it, depending on the nanoaperature’s relative position in the cavity and the polarization state of the incident light. Therefore, the cavity-aperture has the potential to function as a dynamic colour pixel. This design method may be helpful in developing various photonic devices, such as micro-imaging systems and multiplexed sensors.

We propose a multi-viewer tracking integral imaging system for viewing angle and viewing zone improvement. In the tracking integral imaging system, the pickup angles in each elemental lens in the lens array are decided by the positions of viewers, which means the elemental image can be made for each viewer to provide wider viewing angle and larger viewing zone. Our tracking integral imaging system is implemented with an infrared camera and infrared light emitting diodes which can track the viewers’ exact positions robustly. For multiple viewers to watch integrated three-dimensional images in the tracking integral imaging system, it is needed to formulate the relationship between the multiple viewers’ positions and the elemental images. We analyzed the relationship and the conditions for the multiple viewers, and verified them by the implementation of two-viewer tracking integral imaging system.

We propose a real-time integral imaging system for light field microscopy systems. To implement a 3D live in-vivo experimental environment for multiple experimentalists, we generate elemental images for an integral imaging system from the captured light field with a light field microscope in real-time. We apply the f-number matching method to generate an elemental image to reconstruct an undistorted 3D image. Our implemented system produces real and orthoscopic 3D images of micro objects in 16 frames per second. We verify the proposed system via experiments using Caenorhabditis elegans.