立体显示中的垂轴放大率

为消除立体影像的畸变需研究拍摄再现立体影像的垂轴放大率。重新推导了立体影像拍摄再现的总垂轴放大率公式,在该公式中增加了一个观看再现放大率系数,立体影像的观看再现垂轴放大率为像距与观看距离之比。实验结果验证了理论的正确性,该公式对于进一步研究再现立体影像的消畸变具有重要作用。     

Design of unobscured reflective zoom system with three mirrors

A method for the design of an unobscured reflective zoom system with three mirrors is described. This method applies the vector aberration theory, which helps designers analyze third-order aberrations for optical systems with decentered and tilted surfaces. As the vector aberration theory presents the variation of third-order aberrations in asymmetric systems through analytic expressions, real ray tracing is unnecessary. Hence, the design with vector aberration theory is faster, and the analytic expressions are more comprehensive and intuitive. To demonstrate the practicability of the method, a design example is given, which shows that the presented method can guide designers achieve a good unobscured reflective zoom system with three mirrors.     

Boundary segmentation based on modified random walks for vascular Doppler optical coherence tomography images

Vascular Doppler optical coherence tomography(DOCT) images with weak boundaries are usually difficult for most algorithms to segment. We propose a modified random walk(MRW) algorithm with a novel regularization for the segmentation of DOCT vessel images. Based on MRW, we perform automatic boundary detection of the vascular wall from intensity images and boundary extraction of the blood flowing region from Doppler phase images. Dice, sensitivity, and specificity coefficients were adopted to verify the segmentation performance. The experimental study on DOCT images of the mouse femoral artery showed the effectiveness of our proposed method, yielding three-dimensional visualization and quantitative evaluation of the vessel.     

自由曲面成像光学系统设计:理论、发展与应用

传统球面以及非球面可供光学系统设计使用的自由度较少。自由曲面打破了旋转对称以及平移对称的几何约束,特别适用于校正非旋转对称系统的像差,同时可以减少系统中元件的数量,减小系统的体积与质量,实现传统光学系统难以实现的系统参数、结构与功能。自由曲面为光学设计的发展注入了巨大潜力,但同时也带来了全新的困难与挑战。概括性地总结了自由曲面成像系统设计的研究现状。简要介绍了自由曲面的常用数学描述与自由曲面成像系统的像差理论,总结了自由曲面成像系统的设计方法,并对自由曲面在各类成像系统中的应用进行概述。最后,对自由曲面成像光学设计的未来发展方向进行了讨论与展望。     

Lightweight spatial-multiplexed dual focal-plane head-mounted display using two freeform prisms

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 headmounted 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.     

一种抗干扰的弱小目标检测方法

针对低信噪比灰度图像中弱小目标的检测问题,提出了SUSAN特征检测原则与数学形态学方法结合的小目标检测方法.该方法首先采用SUSAN原则利用图像灰度级直接提取特征,利用形态学算子去除噪声、分离目标.给出了应用实例,实验结果表明,这种方法抗干扰能力强,能够快速、可靠地检测出小目标.     

Optical reconstruction of 3D images by use of pure-phase computer-generated holograms

A three-dimensional （3D） object reconstruction technique that uses pure-phase computer-generated holograms （CGHs） and a phase-only spatial light modulator （SLM） is proposed. The full parallax CGHs are generated by the point source method and the wave-oriented method without paraxial approximation. Different from conventional CGHs, the pure-phase information on the hologram plane is loaded on the SLM to reconstruct the 3D diffusive objects without considering the reference wave. This technique is more efficient in its utilization of the space-bandwidth product of the SLMs. Numerical simulations and experiments are performed, and the results show that our proposed method can reconstruct 3D diffusive objects successfully.     

基因算法在光学系统优化中的应用

将基因算法植物于光学系统的优化中，构造了相应的数学模型，并编程实现了算法，实验证明基因算法可以克服以往优化算法不能自动增减光学面（元件）的缺点，从而提高了光学系统设计的智能化程度。     

多组元全动型变焦距透镜高斯光学参数的求解方法

在求解多组元全动型变焦距透镜高斯光学参数的过程中，不再区分变倍组与补偿组的概念，统一将变焦距系统运动组元的移动距离和焦距作为变量，并将组元的F数作为约束条件，提出了一种能同时求解多组元全动型变焦距系统在每个变焦位置高斯光学参数的计算方法，并给出了设计实例，证明了算法的可行性，提高了光学系统设计的智能化程度。     

增强现实三色立体基准注册技术的研究

讨论了在增强现实 ( Augment Reality)的三色立体基准注册 ( Registration)技术中需要解决的问题。增强现实的三色立体基准注册技术是一种新的基于视觉的三维注册技术 ,主要论述了在此三维注册技术中如何通过滤波消除三色立体基准注册中的图像噪声以及如何通过重心拟和法获得注册基准的像斜率。