Typical fundus photography produces a two-dimensional image. This makes it difficult to observe the microvascular and neural abnormalities, because the depth of the image is missing. To provide depth appreciation, we develop a single-channel stereoscopic fundus video imaging system based on a rotating refractor. With respect to the pupil center, the rotating refractor laterally displaces the optical path and the illumination. This allows standard monocular fundus cameras to generate stereo-parallax and image disparity through sequential image acquisition. We optimize our imaging system, characterize the stereo-base, and image an eyeball model and a rabbit eye. When virtual realities are considered, our imaging system can be a simple yet efficient technique to provide depth perception in a virtual space that allows users to perceive abnormalities in the eye fundus.

We present a high dense views auto-stereoscopic three-dimensional display method with the projectors array and lenticular lens array (LLA) screen. The principle and configuration are demonstrated. This display method utilizes lenticular screen to modulate the information of projectors. To increase the dense of views, we propose a novel arrangement way of projectors array. In the experiment, the viewer can obtain smooth motion parallax and evident stereo feeling at optimal distance. Through analyzing and observation, the maximum display depth is found to be more than 50 cm.

Accommodation and convergence play critical roles in the natural process of depth perception, and the field of natural three-dimensional (3D) perception in stereo displays has been extensively explored. However, no prototypes of these natural 3D displays are suitable for wear due to the system size and weight. In addition, few of the researches have involved subjects with ametropia. We propose and develop an optical see-through head-mounted display (HMD) capable of diopter adjustment of both the virtual image and the real world scene. The prototype demonstrates a diagonal field of view (FOV) of 42o and an exit pupil diameter of 9 mm, and a diopter adjustment range of -5.5D to 0D. Depth adjustment of virtual image is demonstrated with experiments, the results show the HMD can be further used to investigate the accommodation and convergence cues in depth perception in AR environment, particularly for users with different degree of the ametropia.

A new type of light field display is proposed using a head-mounted display (HMD) and a micro structure array (MSA, lens array or pinhole array). Each rendering point emits abundant rays from different directions into the viewer’s pupil, and at one time the dense light field is generated inside the exit pupil of the HMD through the eyepiece. Therefore, the proposed method not only solves the problem of accommodation and convergence conflict in a traditional HMD, but also drastically reduces the huge data in real three-dimensional (3D) display. To demonstrate the proposed method, a prototype is developed, which is capable of giving the observer a real perception of depth.

We propose a large parallax barrier by use of aperture grille. Main advantages of using aperture grille include no reflection and no absorption in apertures, as well as wide viewing angle. These advantages are investigated with theoretical calculations and experiments by use of several kinds of LED panels, such as a fine-pitch LED panel and a 140-inch large LED panel. Limitations of viewing angle by parallax barrier are analyzed in conventional black stripes on a transparent substrate type and in aperture grille type.Experimental results show use of aperture grille increases contrast and reduce reflection on the aperturesurface.

Accommodation and convergence play critical roles in the natural viewing of three-dimensional (3D) scenes, and these must be accurately matched to avoid visual fatigue. However, conventional stereoscopic head-mounted displays lack the ability to adjust accommodation cues. This is because they only have a single, fixed image plane, but the 3D virtual objects generated by a pair of stereoscopic images are displayed at different depths, either in front or behind the focal plane. Therefore, in order to view objects clearly, the eyes are forced to converge on those objects while maintaining accommodation fixed on the image plane. By employing freeform optical surfaces, we design a lightweight and wearable spatial-multiplexed dual focal-plane head-mounted display. This display can adjust the accommodation cue in accordance with the convergence cue as well as generate the retinal blur cue. The system has great potential applications in both scientific research and commercial market.

In three-dimensional displays, large vertical parallax in parallax images is disadvantageous to stereo vision due to the presence of visual fatigue. Based on the principle that homologous points in different parallax images correspond to the same object point, a method is proposed to eliminate the vertical parallax in multi-view parallax images. The coordinate mapping relationship between a standard parallax image and an awaiting rectification parallax image is established according to the coordinates of the image points of the rectangular calibration board vertices. Experiments are conducted, and results prove that the proposed method is reliable.