The simplest way to achieve high-resolution imaging is by increasing the number of pixels per unit area of the image sensor. However, this can lead to smaller pixel sizes, which in turn increases scattering noise, ultimately degrading image quality and raising costs. Super-resolution (SR) imaging involves acquiring a sequence of images of the same scene with slight displacements and then synthesizing these to create a higher-resolution image. The multi-frame SR reconstruction technique primarily involves: 1) sub-pixel shifted image acquisition of the same scene, 2) alignment of the acquired images, and 3) the use of interpolation methods to obtain higher-resolution images. Conventional methods that involve using double optical wedge rotation and liquid crystal lens optical axis shift suffer from significant image distortion, complex control mechanisms, and slow response speeds. We propose a super-resolution imaging system utilizing a liquid crystal optical wedge device that electronically modulates beam deflection to acquire sub-pixel shifted images. By simply adjusting the amplitude of the applied voltage, the deflection angle and direction of the beam can be precisely controlled without mechanical movement. The liquid crystal optical wedge device can achieve a minimum thickness of just a few micrometers, resulting in fast response times.

In this study, we propose a super-resolution imaging system that incorporates a liquid crystal optical wedge device paired with a polarizer and a fixed focal length camera module. We first introduce the principle of electronically modulated beam deflection within the liquid crystal optical wedge and theoretically analyze the relationship between beam deflection and image displacement. A sequence of images of the same scene is captured at varying driving voltages, and the average displacement between images is measured using the Keren alignment method. Experimental results demonstrate that electronically modulated sub-pixel image shifts are achieved within acceptable error margins. The limiting resolution and modulation transfer function (MTF) of the images are evaluated using HYRes and Imatest software, respectively, to quantify improvements in image resolution and contrast.

The initial image of the ISO12233 resolution chart is shown in Fig. 9. Using HYRes software, we measure the TV lines in both vertical and horizontal directions to determine the limiting resolution for the initial image, a single-frame interpolated image, and the multi-frame super-resolution image, as shown in Table 2 and Fig. 11. The comparison shows that the resolution of the synthesized multi-frame super-resolution image is improved by 55.0% and 58.8% in the vertical and horizontal directions, respectively, compared to the initial image, and by 24.6% and 37.2% compared to the single-frame interpolated image. The modulation transfer function curve, obtained using Imatest software to measure a black-and-white diagonal pattern with a specific tilt angle, is shown in Fig. 12. The curve indicates that the multi-frame super-resolution image effectively enhances image contrast in high-frequency regions due to the introduction of additional information.

We report on an optical system designed for super-resolution imaging using a liquid crystal optical wedge device capable of electrically modifiable beam deflection. The device’s electrode structure and beam deflection principle are discussed, and the theoretical relationship between image displacement and applied voltage is analyzed. Experimental results show that the device can accurately achieve image sub-pixel image displacement without mechanical movement. The liquid crystal optical wedge device used in this study features a 2 mm×2 mm square aperture in its working area and a device box thickness of 5 μm. By shifting the beam deflection direction three times, a sequence of four images with defined displacement is captured, enabling multi-frame super-resolution imaging. HYRes software is used to measure the limiting resolution of the multi-frame super-resolution image, the initial image, and the bicubic linear interpolated image. The comparison shows a significant enhancement of approximately 55.0% relative to the initial image. Compared with other methods for acquiring multi-frame images, the device used in this study offers advantages such as no mechanical movement, a simple driving method, fast response time, and no effect on the optical focus of the system, making it a viable solution for achieving high-resolution imaging in large-scale systems.