改善轴向分辨率的光瞳滤波器

给出了一种新型滤波器,它即能提高系统的轴向分辨率又不影响其横向分辨率。利用这种滤波器不可以控制远场旁瓣强度的最大值与主瓣强度最大值之比（Ｍ）,从而获得较好的超分辨效果,还根据扩展结果分析了光瞳滤波器的中间区对轴向分辨率的影响。     

Discrete continuous-phase superresolving filters

A new type of phase-only superresolving pupil filter with a discrete continuous-phase profile is presented that is a combination of discrete multilevel-phase modulation and continuous-phase modulation. This type of filter can achieve better superresolution performance than the continuous-phase filters reported in Opt. Lett. 28, 607 (2003). Therefore, with regard to the superresolution effect, this type of filter deserves study for practical applications. More importantly, the diffraction performance of this type of filter can explain the effect of a discrete-phase filter illuminated with a continuous wave front, whose superresolving performance cannot be analyzed with previous superresolution methods.     

消色差相位型超分辨光瞳滤波器的设计研究

提出并设计了一种消色差的相位型超分辨光瞳滤波器。详细分析了滤波器的设计参数对成像系统的光斑压缩比和斯特雷尔比影响。分别以方解石晶体和石英玻璃材料为例进行了设计,当光斑压缩比为0.83时,得到两种材料的消色差超分辨光瞳滤波器,可以分别在380～555nm和300～600nm的波长范围内实现消色差,同时可以有较高的斯特雷尔比。     

Quasi-achromatic superresolving phase only pupil filters

Reported in this paper is a new design of the quasi-achromatic phase-only superresolving pupil filters (QAPSFs) relatively independent of wavelength based on the zero order Bessel function of the first kind. The effect of design parameters of the new filters on the superresolving performance parameters such as the normalized spot size (G) and the Strehl ratio (S) is discussed and analyzed in detail. As an example, the performance parameters of QAPSFs made of optical quartz glass are simulated and compared with phase only pupil filters, which indicate that this kind of filters is less independent of wavelength in the range from 300 nm to 589 nm for superresolution, and a high Strehl ratio is also obtained. The equivalent performance parameters are derived to characterize the superresolution performance of the quasi-achromatic filter.     

Filter performance parameters for high-aperture focusing

Performance parameters for focusing, widely used to investigate the properties of pupil filters, are extended to the scalar nonparaxial regime. These measures can be used to investigate focusing properties of different types of focusing systems, including those with apodizers and superresolving masks.     

等宽圆环光瞳滤波器的超分辨性能研究

设计一种等宽圆环光瞳滤波器 ,并研究了它的超分辨性能。分析了光瞳中心半径和圆环数对斯特耳比、超分辨能力和旁瓣强度的影响 ,讨论了设计等宽圆环光瞳滤波器时中心半径和圆环数的优化问题。表明圆环数为奇数和偶数时 ,光瞳具有不同的超分辨性能 ;圆环数分别取 1和 2时 ,综合考虑超分辨性能较佳     

复振幅光瞳滤波器的三维超分辨性能研究

超分辨技术中现有的纯振幅型或纯相位型光瞳滤波器,大部分只能实现轴向或横向超分辨而不能实现三维超分辨,三维超分辨在三维成像系统中有着重要的作用。因此为提高成像系统中的三维分辨能力,设计了一种复振幅光瞳滤波器,并对其三维超分辨性能进行了研究。详细分析了该光瞳滤波器的第一区半径和透射率对施特雷尔比、轴向和横向超分辨因子以及旁瓣能量的影响。通过一系列的模拟证明,借助于复振幅光瞳滤波器可以实现三维超分辨。该滤波器的优点是容易实现三维超分辨,且有比较高的施特雷尔比,缺点是三维超分辨的实现总是伴随着旁瓣能量的增加,但可以采用共焦扫描成像系统来加以抑制。     

Pupil apodization for increasing data storage density

We introduce a technique for increasing density in optical data storage systems. This technique is based on the use of a superresolving filter at the pupil of a confocal readout system. The main characteristic of this confocal readout system is that the light beam traverses twice through the pupil filter. We describe how to analyze the system performance for general filters, but we focus the study on filters with no focus displacement. Although the storage density attainable depends on the filter characteristics, we show that the storage density can be easily duplicated.     

基于矢量衍射理论的相位型光瞳滤波器设计

根据矢量衍射理论,提出了一种设计纯相位型光瞳滤波器的新方法根据该方法所设计的滤波器主要应用于采用高数值孔径显微物镜的成像系统对点扩散函数中的指数因子进行二次近似处理后,可以得到超分辨参量与滤波器参量的近似关系式以三区相位型滤波器为例,讨论了该近似关系式的有效性给出一个设计实例,根据所要求的超分辨性能要求设计滤波器.模拟结果表明,该滤波器达到了设计要求,最后利用共焦系统点扩散函数的乘积特性,大大减弱了旁瓣的影响.     

三区振幅型超分辨光瞳滤波器的设计

提出运用非线性规划及目标规划法,在给定斯特雷耳比S(超分辨模型和艾里模型主瓣最大亮度比)的条件下,设计出使成像系统的横向、轴向及三维分辨率分别达到最大值的环形振幅型超分辨光瞳滤波器。给出超分辨优化设计模型和实例,并作图验证其结果。对超分辨率伴随的旁瓣效应,把滤波器应用于共焦扫描系统,可有效地抑制旁瓣,提高成像信噪比和对比度。此方案用于三区以上振幅型超分辨滤波器及环形纯相位超分辨光瞳滤波器的设计,为超分辨滤波器的设计提供了参考。     

双模式高精度可调超分辨光瞳滤波器

基于双折射波片的特性,提出了一种具有双调节模式的连续可调超分辨光瞳滤波器。该滤波器通过两种调节模式实现超分辨,且在一定范围内连续可调。在横向旋转模式下,该滤波器为复振幅型光瞳滤波器,纵向倾斜模式下为纯相位型超分辨滤波器。通过对超分辨参量的分析,得到最佳设计参量,可以实现大的视场角,大的超分辨范围、高的调节精度。这种滤波器为实际应用提供了更多的方便。     

Superresolved femtosecond laser ablation

The determinist behavior of the femtosecond ablation process allows morphing features well under the diffraction limit by utilizing the thresholding effect, down to the nanometer scale. Because there are a vast range of applications where scaling down the size of the features is a major concern, we investigate the use of superresolving pupil plane filters. As is well known, these filters redistribute the focused optical intensity for a narrower bright spot and, as a trade-off, increase the sidelobes. However, this drawback can be rendered insignificant if all the outer optical power is kept under the determinist threshold value. Two types of pure absorbing binary filter have been tried, giving credence to a size reduction of the ablations in fused silica.     

用于高数值孔径物镜的可调光瞳滤波器

根据矢量衍射理论，提出了一种用于提高高数值孔径显微物镜纵向分辨率的可调二元环形光瞳滤波器，通过改变滤波器的环半径获得不同的纵向分辨率，并利用共焦显微术点扩散函数的乘积性大大地降低了旁瓣相对主瓣的比值。模拟结果表明，这种新型滤波器不仅可以提高高数值孔径物镜的纵向分辨率，同时基本上不影响横向分辨率。     

High depth of focus by combining annular lenses

In some technological applications, optical systems that produce a high depth of focus and superresolving transversal responses are required. In this paper we present a pupil design consisting in a phase pupil with binary amplitude, that added to a conventional optical system, can accomplish these goals. The pupil function is characterized by a complex amplitude that consists basically in combining two annular lenses with different focal length. Meanwhile the central portion of the pupil has an amplitude equal to 0, the external portion is modulated with two quadratic phases each one covering an annular zone. One of the phases corresponds to a convergent lens and the other to a divergent lens. The effect on the incident wavefront is to redirect the light in front of and behind the best image plane (BIP) producing a widened focus. The evolution of the transverse gain for the extended focus is also studied. Experimental results are given, and they confirm the extended focus and the superresolving behavior of the proposed pupil function.     

超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量

采用电磁场有限元方法,数值模拟了孔径型扫描近场光学显微镜(aperture Scanning Near-field Optical Microscopy,a-SNOM)在照明模式下的工作过程.针对金偶极天线结构,改变天线长度和纳米间隙尺寸,计算了a-SNOM探针孔径的远场辐射速率随探针端面中心坐标变化的扫描曲线,实现了超越a-SNOM探针通光孔径尺寸的天线金属纳米间隙的超分辨测量,对于100nm通光孔径的探针,可分辨最小尺寸为10nm(0.016倍波长)的金属间隙.通过对比金属和介质偶极天线的a-SNOM探针远场辐射速率测量的计算结果,表明天线金属纳米间隙的超分辨测量的实现是由于金属间隙表面等离激元的激发.     

Multiple image encryption using an aperture-modulated optical system

A multiple image cryptosystem based on different apertures in an optical set-up under a holographic arrangement is proposed. The system is a security architecture that uses different pupil aperture mask in the encoding lens to encrypt different images. Based on this approach multiple encryption is achieved by changing the pupil aperture arrangement of the optical system among exposures. In addition to the classical speckle phase mask, the geometrical parameters characterizing the apertures are introduced to increase the system security. Even when an illegal user steals the speckle phase mask, the system cannot be broken into without the correct pupil geometrical parameters. The experimental set-up is based on a volume photorefractive BSO crystal as storing device. Information retrieval is done via a phase conjugation operation. We also have to stress that the multiple storage under this scheme, is only possible with the help of the aperture mask. Simulation and experimental results are further introduced to verify the proposed method.     

共焦显微镜中变距圆光栅函数掩模的研究

针对带有光瞳掩模的超分辨系统,提出了一种基于极坐标的性能 价标准,同时根据衍射光学相关理论,提出了变距圆光栅函数掩模花样。模拟计算结果表明,在共焦系统中掩模可以改变系统的点振幅响应,从而提高分辨率,并增强图像的反衬度。     

Optical sectioning by two-pinhole confocal fluorescence microscopy

A two-pinhole axially superresolving confocal fluorescence imaging system is presented. Based on the concept of subtractive incoherent imaging, the system described here is equipped with a zero-focus complex-transmittance pupil filter in one of the collector paths. The optical sectioning capacity of the system is 25% superior to that of a free-pupil one-pinhole instrument.     

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.     

A Highly Efficient Superresolving Phase Filter for a Radially Polarized Beam

We simulate the focal intensity distribution of a radially polarized beam, in view of the vector diffraction theory. We summarize two important rules: (i) the marginal ray of the aperture determines the focal size on the focal plane; (ii) the ratio of the longitudinal component to the transversal component affects the shape of the focus. We design a continuous phase filter using these rules for a confocal system. We chose the tangent of the semi-aperture angle to build up the phase function, because it is sensitive to the marginal rays, which have large aperture angles. To achieve a flexible modulation, we use a quadratic function for unwrapping the phase. We optimize the parameters of the quadratic function and achieve a transverse superresolving focus. Aiming at different Strehl ratios, we obtain a series of superresolution phase filters. Compared with others, the filter proposed has the advantages of superior superresolution effect and higher energy utilization ratios. The phase-filter design is universal and proved to be valid. It can be employed in either high or low NA systems, superresolving or donut focus applications.