The optimization of imaging accuracy and speed is a crucial issue in the development of computer-generated holograms (CGH) for three-dimensional (3D) displays. This paper proposes an optimized iterative algorithm based on the angular spectrum method (ASM) to achieve high-quality holographic imaging across multiple planes. To effectively utilize spatial resources for multi-image reconstruction and mitigate the speckle noise caused by the overlapping of target images, constraint factors are introduced between different layers within the same region. The seeking rule of the constraint factor is also analyzed. By utilizing both constraint factors and variable factors, the presented method is able to calculate phase holograms for target figure imaging at four different planes. Simulation and experimental results demonstrate that the proposed method effectively improves the overall quality of the different planes, thus holding great potential for wide-ranging applications in the field of holography.

At present, aircraft radome coating cleaning mainly relies on manual and chemical methods. In view of this situation, this study presents a trajectory planning method based on a three-dimensional (3D) surface point cloud for a laser-enabled coating cleaning robot. An automated trajectory planning scheme is proposed to utilize 3D laser scanning to acquire point cloud data and avoid the dependence on traditional teaching–playback paradigms. A principal component analysis (PCA) algorithm incorporating additional principal direction determination for point cloud alignment is introduced to facilitate subsequent point cloud segmentation. The algorithm can adjust the coordinate system and align with the desired point cloud segmentation direction efficiently and conveniently. After preprocessing and coordinate system adjustment of the point cloud, a projection-based point cloud segmentation technique is proposed, enabling the slicing division of the point cloud model and extraction of cleaning target positions from each slice. Subsequently, the normal vectors of the cleaning positions are estimated, and trajectory points are biased along these vectors to determine the end effector’s orientation. Finally, B-spline curve fitting and layered smooth connection methods are employed to generate the cleaning path. Experimental results demonstrate that the proposed method offers efficient and precise trajectory planning for the aircraft radar radome coating laser cleaning and avoids the need for a prior teaching process so it could enhance the automation level in coating cleaning tasks.

In order to accurately measure the phase modulation capability of the spatial light modulator (SLM) and improve its performance in optical applications, a multi-region phase response calibration scheme of SLM based on the Shack–Hartmann wavefront sensor (SHWS) is proposed. This scheme addresses the nonlinear sampling issue of the liquid crystals in different sampling areas on the SLM. By loading and shifting dual sine phase patterns, continuous variations of grayscale values in the same region on the SLM screen were achieved, with the corresponding wavefront data recorded by the SHWS after each grayscale change. Matrix calculations were performed in MATLAB to obtain the corresponding phase modulation curve. Subsequently, the multi-zone phase modulation characteristics of the SLM were measured. Following the nonlinear calibration of phase modulation in each zone of the SLM, the intrinsic wavefront distortion (WFD) of the SLM was measured using the SHWS in conjunction with the calibration results and compensated for. The compensated WFD of the SLM is reduced from 0.7976λ to 0.3415λ (λ=632.8nm), and in the verification experiment, the focused spots’ quality was greatly improved with the calibrated SLM. The experimental results proved the availability of the multi-region phase response calibration scheme. Compared to conventional methods, this approach demonstrates simplicity, real-time performance, and robustness.

The paper looked into concepts claimed to be essence of Chinese residential college, an on-going institution presumed to be a solution towards undergraduates’ issues in some pioneer universities in China. It’s analyzed that Chinese residential college today in China is not a Shuyuan that was ever striving as a unique education mode in ancient China, even if it’s named after Shuyuan in Chinese, concerning on its nature, function and goal, while it’s not a conventional residential college in English speaking countries neither. By investigation and comparison of its origin, function and features among Shuyuan and Chinese residential college, the spirit of development of a human with goodness and well-being through pursuit of knowledge and culture inherited and transmitted in Shuyuan is unearthed, which is supposed to be the resource of inspiration when the pioneer universities and educators designed and operate residential college on Chinese campus, though the effects couldn’t be accounted as appealing as what Shuyuan produced in ancient China. The research aims to depict a real Shuyuan, an education legacy every being alive in Chinese history, which were featured with paramount concepts and values that should be correctly recognized and implemented when there is great concern around undergraduates.