RESUMEN
We propose a structure of a far-field nanofocusing metalens with focal shifting that is actively tuned at visible wavelengths. Surface plasmon polaritons (SPPs) can be excited by the metal-insulator-metal (MIM) subwavelength structure at visible wavelengths. The coherent interference of SPPs emitted by subwavelength nanostructures can form a nanoscale focus. When the SPPs are excited and pass through several concentric ring gratings with specific aspect ratios, the extraordinary optical transmission phenomenon occurs. Two metal concentric ring gratings achieve double diffraction, scattering light to the far field. An anisotropic or isotropic electrically adjustable refractive index material, such as liquid-crystal or optical phase change material, is filled in a dielectric layer between two metal layers, and the effective refractive index is modulated by electronically controlled active tuning. The focal shift is achieved by changing the effective refractive index of the intermediate dielectric. In addition, different incident wavelengths correspond to different effective refractive indices to achieve time-division-multiplexing multi-wavelength achromatic focusing. The finite-difference time-domain method was used to simulate the effect of substrate effective refractive index variation on achromatic superfocusing. The results show that the super-resolution focal spot (FWHM=0.158λ0) with long focal length (FL=5.177λ0) and large depth of field (DOF=3.412λ0) can be achieved by optimizing the design parameters. The visible plasma metalens has potential applications in high-density optical storage and optical microscopic imaging, especially in three-dimensional display for light field and integral imaging.
RESUMEN
The autostereoscopic 3D display has two important indicators, both the number of viewpoints and display resolution. However, it's a challenge to improve both the viewpoint and the resolution. Here, we develop a fixed-position multiview and lossless resolution autostereoscopic 3D display system that includes the dynamic liquid crystal (LC) grating screen. This display system consists of an LC display panel and an LC grating screen. The synchronization of the frame switching of the LC display panel and the LC grating screen shutter enables the preserved resolution. The "eye space" design makes the viewpoint dense enough and determines the LC grating screen's parameters. We use binocular viewpoint tracking technology to realize the LC grating screen's adaptive control based on the above work. Different binocular views are rendered in real-time according to the different positions of a single pair of stereoscopic viewpoints in the eye space, making the motion parallax possible. We present the working principle and mathematical analysis. We implement a prototype for verifying the principle. According to the experiment results analysis, this prototype can achieve viewpoint tracking and motion parallax based on resolution lossless and viewpoint dense enough.
RESUMEN
We came up with a practical setup and simulation for building a glassless autostereoscopic 3D display system based on the concept of "eye space" with a dynamic shutter parallax barrier. "Eye space" is designed based on geometrical optics to get a multi-view as much as possible by adjusting the width of the slit and parallax barrier dynamically. The dynamic parallax barrier is placed in front of the display screen to form the shutter screen. The addressable drive circuit controls the switches of the pupil windows on the shutter screen. The two signals are synchronous with the drive circuit and the frame frequency scanning of the display screen. The shutter parallax barrier makes it possible that all right and left eyes in the "eye space" see their own views simultaneously. The numerical simulation and experimental verification with simplified 1D pupil windows and a field-programmable-gate-array-based driving circuit unit, which have good practical value, are described in this paper.