Defocus deblurring for catadioptric omnidirectional imaging based on coded aperture and omni-total variation

The problem of catadioptric omnidirectional imaging defocus blur, which is caused by lens aperture and mirror curvature, becomes more severe when high-resolution sensors and large apertures are applied. In order to overcome this problem, a novel method based on coded aperture technique is proposed in this article. Firstly, the defocus blur of catadioptric omnidirectional imaging is analyzed to calculate the point spread function for different scene points. Then, a method of obtaining optimal focused plane is proposed. Lastly, based on the strategies of neighboring annuluses division and stitching of omnidirectional images, a deconvolution algorithm using omni-total variation prior is applied to obtain all-focused/sharp omnidirectional images. Experimental results demonstrate that the proposed method is effective for omnidirectional image defocus deblurring and can be applied to most existing catadioptric omnidirectional imaging systems.     

高精度球面检测中调整误差的精确校正

针对高精度球面检测中球面的调整误差影响,分别研究了波前离焦和倾斜所引入的Zernike像差项,并以此为基础,提出了基于Zernike系数的高精度球面调整误差校正方法.利用Zygo干涉仪对大数值孔径的待测球面进行了检测,实验中对待测球面同时引入波前离焦和倾斜误差,再分别运用所提出的校正方法和传统的消倾斜离焦校正方法得到波面数据并进行对比,进而验证了所提出的校正方法的可行性.实验结果表明,利用该方法可有效地校正大数值孔径球面存在调整误差时所引入的球面像差,并且实验中的校正精度达到了0.002λ（λ为检测光波长）.提出的基于Zernike系数的球面调整误差校正方法可降低对于调节机构的精度以及检测人员的经验要求,在高精度球面检测中具有非常高的实际应用价值.     

光学离焦三维传感技术的现状与进展

介绍了近年来光学离焦三维传感技术的研究现状，重点综述了离焦三维传感的原理、技术特点以及主动离焦和被动离焦的实现方法。分析了这两种方法的优缺点。最后讨论了在现有条件下进一步提高离焦三维传感精度的可能性。     

Image sensing model and computer simulation for CCD camera systems

A computational model and a computer simulation system are presented for image sensing in a typical CCD camera system. The computational model makes explicit the sequence of transformations that the light incident on the camera system undergoes before being sensed and recorded. The model is based on a precise definition of input to the camera system that decouples the photometric properties of a scene from the geometric properties of the scene. Based on this model, an interactive research software, the Image Defocus Simulator, has been developed. Application of this software in machine vision research and development is described with examples.     

散焦和运动模糊复合模型及参数估计

为了解决散焦和运动模糊同时存在的图像复原问题,建立了一种散焦和运动模糊复合模型,提出了一种基于自相关的参数估计方法.在分析图像成像过程的基础上,对标准散焦模型和运动模糊模型进行卷积,估计复合模型的分布范围,根据光的散射特性和能量守恒调整复合模糊模型的幅度.对复合模型按两方向分别求导,根据导数矩阵自相关的曲线特性估计模糊参数.实验结果表明,参数估计方法具有较高的估计精度,解决了混叠现象造成的干扰问题,复合模型则能够取得较好的复原效果.     

Impact of the pupil size – central optical zone diameter relationship on visual performance in aspheric multifocal contact lenses

PurposeTo determine the impact of different central optical zone diameters (COZDs), obtained from pupil size, on the visual performance of presbyopic subjects fitted with centre-distance simultaneous-image multifocal contact lenses (SIMCLs).MethodsThirty-two presbyopic volunteers, between 45–58 years of age, participated in this prospective, controlled, double-blind study. Subjects were fitted with 5 centre-distance SIMCLs of variable COZD, determined from the measurement of pupil size under photopic light conditions and corresponding to 60, 70, 80, 90 and 100 % of pupil diameter. Subjects visual performance was evaluated through the measurement of distance, intermediate and near visual acuity (VA), “visual functional range” (VFR) obtained from the VA Defocus Curve (VADC) and Contrast Sensitivity Function (CSF), using a third-generation retina display iPad.ResultsStatistically significant differences were obtained for both distance (p = 0.01) and intermediate (p = 0.001) VA amongst designs. Best results were obtained with 80 % and 90 % COZDs compared to 60 %. No significant differences in VFR (p > 0.05) were obtained amongst the different COZDs. 90 and 100 % COZDs offered statistically significant better results at 6 and 18 cycles per degree (cpd) in the CSF, compared to the 60 and 70 % designs.ConclusionsSIMCLs with COZDs of 80–90 % and of 90–100% of photopic pupil diameter offered better distance and intermediate VA, without a decline in near performance, and superior contrast sensitivity at medium and high spatial frequencies respectively, compared to lower COZD designs.     

点聚焦透镜天线及分辨率的分析与测量

本文分析了点聚焦透镜天线的一些基本特性,采用波动理论方法分析了电磁波经透镜会聚的焦斑的大小和横向空间分辨率,指出点聚焦透镜天线在会聚点的天线特性与相同场分布的平面口径天线在无穷远处的天线特性的关系,提出了透镜天线的分辨率的一种测量方法和使用条件.通过实测,测量结果和理论较为吻合.     

激光图形发生器调焦系统设计

为提高激光图形发生器的线条制作精度和制作效率,设计了新的调焦系统。调焦采用光学离轴探测原理,调焦辅助光源直接采用半导体激光器（LD）的准直椭圆光束,探测器为二象限光电池,离焦信号则采用除法构建。调焦系统具有过阻尼的二阶系统特征,新嵌入的PID控制器提升了系统的动态性能,并使系统闭环精度达0．2μm离焦量,同时能产生预期的基于不同离焦量的变线宽图形。     

柯林斯公式及其逆运算在处理离焦图像中的应用

给出描述光波通过傍轴光学系统衍射的柯林斯公式及其逆运算表达式。根据在数字全息研究中可以将物平面及CCD平面视为ABCD系统的输入平面及输出平面,本文提出通过柯林斯公式的逆运算进行离焦图像复原的一种计算方法,并且,基于相移法和计算机编程技术,给出离焦图像复原的计算机模拟实例,证明了算法的可行性。     

一种基于散焦光栅的光束质量M2因子实时测量技术

设计出相位型正交散焦光栅,实现了一种新的光束质量M2因子实时测量技术。将散焦光栅和短焦透镜密接使用,透镜提供主要的聚焦能力,散焦光栅产生9个光轴,且在每个光轴上对焦距进行微调,使之具有不同的等效焦距,这样利用单一的CCD就可以在透镜焦平面上同时测量待测光束9个不同位置处的光强分布图样。利用二阶矩的方法计算束宽,经双曲线拟合得到光束的M2因子。对He-Ne激光器的输出光束进行了测量,得到其光束质量因子M2=5.775,与传统测量方法得到的结果相比,误差为5.1%。