可调谐位相型光瞳滤波器的横向光学超分辨和轴向扩展焦深

为克服传统光瞳滤波器的缺点，实现系统光学超分辨性能的可调谐性，设计了一种新型可调谐的位相型光瞳滤波器.该光瞳滤波器包括两个λ/4波片和置于其间的λ/2波片，其中λ/2波片分为两个可作相对旋转的区域.研究结果表明，通过旋转λ/2波片的任意一区域不仅可以实现系统横向光学超分辨能力的可调性，而且可以在横向分辨能力提高的同时实现光学系统轴向焦深的扩展以及轴向焦移.     

三环位相型光瞳滤波器的横向超分辨与轴向焦深扩展

用矢量衍射方法分析了线偏振光入射到带有三环位相型光瞳滤波器的高数值孔径物镜时,焦点的轴向和横向光强分布.数值模拟结果表明,高数值孔径物镜聚焦时需同时考虑光强的轴向和横向分布.通过加入三环位相光瞳滤波器,在实现横向超分辨的同时实现了光学系统轴向焦深扩展和轴向光强分布平坦化,并且位相调制深度变化时,会出现轴向焦移现象.对三环位相光瞳滤波器结构进行了优化,得出了优化结果. 关键词： 光学超分辨 扩展焦深 位相型光瞳滤波器 矢量衍射方法     

可调光瞳滤波器的轴向焦移及扩展焦深

光学超分辨、焦深扩展及焦移3种效应一直受到研究人员的关注,且在光学显微成像、光学校准、光学相干层析成像及光存储中有着重要的应用.提出一种可调谐光瞳滤波器来实现光学系统的轴向焦移及扩展焦深.该光瞳滤波器由两个完全相同且相互平行的λ/4波片和置于其间的λ/2波片组成,其中λ/2波片分为两个可作相对旋转的区域,并且通过推导得...     

位相型光瞳滤波器对共焦系统离焦工作状态横向分辨特性的影响

分析了共焦显微系统(CMS)离焦状态工作时分辨特性的变化,指出了离焦状态是导致CMS横向分辨特性变差的主要影响因素之一。提出并采用了位相型超分辨光瞳滤波技术来改善CMS工作在离焦状态下的横向分辨特性,分析了超分辨光瞳滤波器位置变化对CMS横向分辨特性的影响。理论分析和实验验证表明,位相型超分辨光瞳滤波技术的引入,显著抑制了CMS工作在离焦状态时艾里斑旁瓣的增长,克服了CMS因工作在离焦状态而引起的横向分辨特性下降的缺点。     

单轴晶体相位型光瞳滤波器

提出了一种基于单轴晶体制作的相位型光瞳滤波器,与普通的相位型光瞳滤波器相比较,单轴晶体相位型光瞳滤波器不仅制作简单,而且相位差有一定的可调节性。与液晶制作的相位型光瞳滤波器相比较,虽然单轴晶体相位型光瞳滤波器的可调节性不如液晶相位型光瞳滤波器,但是单轴晶体相位型光瞳滤波器成本低,而且也不会对光的衰减过大。单轴晶体相位型光瞳滤波器可以实现对焦斑分布的连续调节。通过理论分析和数值计算,论证了单轴晶体相位型光瞳滤波器的可行性,并且具体设计了两区型的单轴晶体相位型光瞳滤波器。     

正弦变化的振幅型光瞳滤波器

光瞳滤波器作为实现超分辨的基本元件之一,它的设计以及制作都非常重要。设计了一种正弦变化的振幅型光瞳滤波器,可以通过调节少量的参量实现各种不同的超分辨模式。选择正弦函数的周期以及光瞳中心点透过率变化两个参量来实现对最终超分辨效果的调节。数值计算结果表明：在整个人射光瞳上的透过率瞳函数分布具有0．5～2个正弦振幅周期时,较为合适。小于0．5个周期将不会有任何超分辨效果,大于2个周期超分辨效果反而变差。数值计算中还注意到,当周期数为整数时,斯特雷尔比将保持0．25不变。对正弦变化振幅型光瞳滤波器的计算结果,显示了其特殊的性质,对实际中制作正弦变化振幅型光瞳滤波器有一定的指导作用。     

改善共焦系统轴向分辨率的位相型光瞳滤波器

利用约束全局优化算法———CGO算法,设计了两种用于共焦系统的三区位相型光瞳滤波器.第一种滤波器在不改变系统的横向分辨率的同时,可以大幅度地提高轴向分辨率,提高了系统的层析能力.第二种滤波器在提高系统轴向分辨率的同时,又能提高其横向分辨率,适用于系统的三维成像. 关键词： CGO算法 光瞳滤波器 超分辨     

共焦显微系统中光学超分辨光瞳滤波器的设计

利用矢量衍射理论设计了适用于共焦显微等大数值孔径系统的三区二元相位型超分辨光瞳滤波器.数值模拟了等效数值孔径为1.4的共焦显微系统焦点附近的光强分布,根据系统所需要的斯特雷尔比和轴向分辨率,采用优化搜索算法求解了能够实现光学超分辨的三区二元相位型光瞳滤波器结构.结果表明,利用所设计的三区二元相位型光瞳滤波器可以在较低旁...     

多项式型相位光瞳滤波器实现三维超分辨

为研究连续型相位光瞳滤波器对光学成像系统成像效果的影响,并实现对远场光学成像系统分辨率的提升,设计了一种多项式函数形式的相位型光瞳滤波器,证明其可以实现三维超分辨.给出了其与一种典型三区型相位光瞳滤波器的超分辨效果的对比.通过对比可以发现,在分辨效果的改善上,横向分辨率有明显提升,但施特雷尔比会有所下降.此外,由于此种...     

三维超分辨光瞳滤波器的优化设计

利用matlab优化工具箱,采用非线性规划,对三区振幅型(透过率为1-0-1)和三区位相型(相位角为π-0-π)光瞳滤波器进行三维超分辨优化设计,建立了优化模型,经计算机多次迭代运算,改变斯特尔比s值,给出了优化结果.结果显示:所设计的滤波器较好地实现了横向和轴向三维超分辨,且轴向超分辨能力优于横向;相同斯特尔比下,位相型三维超分辨能力优于振幅型,并且这两种滤波器结构简单,容易实现.     

Transverse superresolution and focal shift with rotational tunable phase mask

This paper reports the imaging characteristics of an optical system can be modified by our designed polarization pupil mask. The novel rotational symmetric polarization pupil mask design based on combination of half-wave and quarter-wave plates is introduced for realizing the focal shift and extending focal depth of an optical system and the procedure for designing is presented. Numerical results show when an appropriate rotational symmetric polarization pupil mask is used as an apodizer in the optical imaging system, it not only can effectively achieve the continuously focal shift in a small range and extend focal depth of the optimized system, but also can evidently increase the transverse resolution of the optimized system at the genuine focal plane.     

Transverse superresolution with the radial continuous transmittance filter

The radial continuous transmittance filter is presented to realize transverse superresolution. It consists of two parallel polarizers and a radial birefringent element sandwiched between of them. By adjusting the angle between optical axis of the radial birefringent element and the polarization direction of the polarizers, transverse superresolution can be realized. But transverse superresolution is obtained at the cost of the axial resolution and the increase of the side-lobes in strength. So we then mend such filter, with it not only enhance the transverse resolution but also suppress the influence of the side-lobes and the reduction of the axial resolution. At the same time, the Strehl ratio increases. The advantage of such a filter used in superresolution technique is that it is easy to fabricate because its fabrication does not deal with the variation of the phase.     

Designing superresolution optical pupil filter with constrained global optimization algorithm

In this paper, a new method for designing three-zone optical pupil filter is presented. The phase-only optical pupil filter and the amplitude-only optical pupil filters were designed. The first kind of pupil for optical data storage can increase the transverse resolution. The second kind of pupil filter can increase the axial and transverse resolution at the same time, which is applicable in three-dimension imaging in confocal microscopy.     

Transverse superresolution with extended depth of focus using binary phase filters for optical storage system

This paper reports the study of superresolution and extension of depth of focus (DOF) of three-zone binary phase filters (BPFs) under high numerical aperture (NA) focusing. Two three-zone BPFs (BPF1 and BPF2) are specially designed to achieve transverse superresolution and extension of DOF simultaneously for the optical disc system with an objective lens of NA = 0.65. Numerical simulations based on the vectorial diffraction theory indicate that the transverse focal spot size of this system can be as small as that of NA = 0.85 and its DOF is as large as that of NA = 0.6 with acceptable Strehl ratios (> 0.4 for BPF1 and > 0.35 for BPF2) and low side-lobe intensity ratios (< 10%) by using these BPFs. It suggests that the storage capacity of this optical storage system may be improved to the same as that of a system with an objective lens of NA = 0.85. Moreover, the strict requirement of the focusing servo system caused by decreasing wavelength or employing higher NA objective lens can be mitigated. Therefore, these BPFs presented in this paper should be highly interesting for applications of high density optical data storage.     

Optimized phase pupil masks for extended depth of field

By properly designing a phase pupil mask to modulate or encode the optical images and then digitally restoring them, one can greatly extend the depth of field and improve image quality. The original works done by Dowski and Cathey introduce the use of a cubic phase pupil mask to extend the depth of field. The theoretical and experimental researches all verified its effectiveness. In this paper, we suggest the use of an exponential phase pupil mask to extend the depth of field. This phase mask has two variable parameters for designing to control the shape of the mask so as to modulate the wave-front more flexible. We employ an optimization procedure based on the Fisher information metric to obtain the optimum values of the parameters for the exponential and the cubic masks, respectively. A series of performance comparisons between these two optimized phase masks in extending the depth of field are then done. The results show that the exponential phase mask provide slight advantage to the cubic one in several aspects.     

三区位相型三维超分辨光瞳滤波器的优化设计

用Matlab优化工具箱,采用非线性规划,对三区位相型(π-0-π型)光瞳滤波器进行了优化设计。结果显示,所设计的滤波器较好地实现了横向和轴向的三维超分辨,且轴向超分辨能力优于横向。该滤波器结构简单,容易实现。     

基于可调谐复振幅滤波器的超长焦深矢量光场

根据矢量光场衍射积分理论和离散复振幅光瞳滤波原理, 通过一种由双λ/2波片和离散复振幅滤波器组成的可调谐复振幅滤波器, 研究了大数值孔径下超长焦深聚焦矢量光场的构建与调控. 给出了一个六环带区的离散复振幅滤波器, 对入射光场的偏振态、振幅滤波和相位滤波三者进行同步优化, 获得了焦深接近10λ的三维平顶光场; 通过调控双λ/2波片夹角来改变聚焦光场的矢量化结构, 使之在光针场、平顶光场、光管场及中间结构光场之间交替变化. 研究结果揭示了入射光场矢量化结构演化与聚焦光场矢量化结构变换之间的关系, 解决了获取动态的、可调控的超长焦深聚焦光场的问题. 两种基本的聚焦光场光针场、光管场的独自使用或三维平顶光场的调和使用, 将会在光学显微、光学微纳操控以及光学精细加工领域获得重要应用.