共查询到18条相似文献,搜索用时 406 毫秒
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波前编码系统是一种新型的光学数字混合成像系统。利用光阑处放置优化设计的三次相位板对波前的调制作用,可以实现在像面附近相当范围内系统的点扩展函数一致;进一步通过数字图像去卷积算法可以得到相当景深范围内清晰的成像,从而实现景深延拓。根据传统显微系统的特点,提出了一种基于传统显微物镜系统的波前编码显微系统设计思路,设计并加工了一套10×,40×波前编码显微成像系统。基于传统显微系统的波前编码显微系统可以有效地延拓传统显微物镜系统的景深,提高系统的成像质量。 相似文献
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设计了一款采用波前编码技术的虹膜采集光学系统,以实现大景深、自然非约束状态下的成像.以传统的光学系统评价指标斯特利尔比和能量集中度作为波前编码系统的成像特征,利用ZEMAX软件对波前编码系统进行设计,权衡了离焦不敏感性和图像可恢复性.比较了带有立方相位编码板和带有修正项的立方相位编码板的虹膜采集系统以及传统系统的焦深延拓效果.发现采用立方相位编码板的虹膜采集光学系统的焦深延拓效果最佳,其焦深是传统系统的8倍.该系统增大了虹膜采集的距离,对于自然状态虹膜成像系统设计有一定的参考价值. 相似文献
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变焦光学系统在连续变焦过程中,由于变焦曲线的计算和加工精度,导致实际像面离焦,成像质量下降。变焦系统的特点是长焦距对应窄视场,短焦距对应宽视场。将波前编码技术应用于变焦系统,在系统的光瞳面设置相位掩模,则扩展了原系统的焦深和景深,使调制传递函数对离焦不敏感,同时提高短焦距宽视场的边缘成像质量。文章对原系统和应用波前编码技术的新系统的成像特性进行了分析和对比,随后讨论了掩模板的相位因子对系统的景深、焦深延拓以及对像质的稳定作用。仿真显示:变焦波前编码光学系统对离焦不敏感,可以很好地扩大系统的焦深和景深、稳定边缘视场的像质,具有很高的实用价值。 相似文献
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应用费希尔信息量评价函数的波前编码系统设计 总被引:1,自引:0,他引:1
在兼顾图像恢复能力的基础上,将不同物距下点扩展函数相似性的评价函数费希尔信息量(Fisher Information,FI)应用到波前编码实际光学系统相位板的优化设计中。在焦距和孔径之比为3、有效焦距为100 mm的无穷远成像的双胶合系统的基础上,设计得到了双胶合-波前编码系统。通过解码前后的点扩展函数模拟和实验结果表明,该系统在5 m到无穷远的物距范围内很好地调制了系统的点扩展函数,使得它对物距不敏感。最后通过对位于5 m,10 m和15 m的三人分别进行传统双胶合成像和双胶合-波前编码系统的成像实验对比,有力地证明了双胶合系统的清晰成像的物距范围从10 m到无穷远扩展到5 m到无穷远,这使得光学系统景深得到很大的延拓。 相似文献
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<正>Wavefront coding(WFC) is used to extend the field depth of an incoherent optical system by employing a phase mask on the pupil.We uses a Fisher information(FI) metric based optimization method to design a phase mask by taking the modulation transfer function(MTF) of the practical optical system into consideration. This method can modulate the wavefront so that the point spread function and optical transfer function are insensitive to the object distance.The simulation results show that the optimized phase mask based on the proposed method can further improve the defocusing image quality while maintaining the focusing image quality. 相似文献
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Optical systems are analyzed with three kinds of rotational symmetric pupil masks: annular Gaussian ring mask, supergaussian ring mask, and quartic phase mask. In these masks, the quartic phase mask is found to be the best one to extend focal depth. Point spread function (PSF) and Strehl ratio (SR) are used to evaluate the imaging quality of the system with different defocus parameters. Without decoding needed, the focal depth of the system with quartic phase mask is four times as deep as aberration-free system. Different from the others, it suffers no obvious loss in the light throughput and lateral resolution.With twice focal depth extension, supergaussian ring mask suffers less loss in light throughput and lateral resolution than annular Gaussian ring mask. 相似文献
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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. 相似文献
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Wave-front coding is a well known technique used to extend the depth of field of incoherent imaging system. The core of this technique lies in the design of suitable phase masks, among which the most important one is the cubic phase mask suggested by Dowski and Cathey (1995) [1]. In this paper, we propose a new type called cubic sinusoidal phase mask which is generated by combing the cubic one and another component having the sinusoidal form. Numerical evaluations and real experimental results demonstrate that the composite phase mask is superior to the original cubic phase mask with parameters optimized and provides another choice to achieve the goal of depth extension. 相似文献
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本文利用稳相法从本质上分析了三次相位波前编码系统的点扩散函数特性.通过分析三次相位板任意位置掩膜带和点扩散函数的关系,指出点扩散函数和稳相点的关系:两个稳相点引起点扩散函数的振荡,一个稳相点则只会造成点扩散函数的平稳变化.相位掩膜带或相位掩膜对的对称结构是同一区域内存在两个稳相点的必要条件,对称结构的不同位置对应于点扩散函数的不同部分.这种对应关系同时解释了对焦点扩散函数只存在振荡,而离焦点扩散函数却还存在平缓变化区域的本质原因,这是由离焦时光学对称轴和几何对称轴不重合引起的.本文建立了点扩散函数和对称相位掩膜对之间的对应关系,可以有效地指导相位掩膜的加工和检验. 相似文献
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波前编码系统采用在传统光学系统中加入相位板来扩大光学系统的景深而避免传统景深延拓技术的不利影响. 由于相位板的参数不可调, 整个系统的景深延拓扩展率也不能动态可调. 采用两相位板组合的方法可以有效克服这一点. 本文首先从光线差的角度提出了两三次相位板组合下的光线像差分布以及点扩散函数尺寸的具体关系表达式, 直观体现了系统的光线结构, 指出了光线结构和点扩散函数尺寸受两三次相位板的面型和相对位移量的影响. 其次采用稳相法从空间域给出了系统点扩散函数表达式, 依据点扩散函数的振荡性质给出了有效带宽表达式, 提出了点扩散函数在像面的位置会随两相位板面型参数以及相对于光瞳中心的位移量而发生平移. 最后利用菲涅耳积分给出两三次相位板任意面型参数和相对位移组合下的准确光学传递函数. 在得到的调制传递函数中直观体现出了面型参数和相对位移量对调制传递函数和相位传递函数以及有效带宽的影响, 并说明了此系统相位传递函数的非线性性质. 通过空间域与频率域相结合的方法分析验证了传统的两三次相位板组合具有景深可调和带宽可调的性质, 为设计可调谐波前编码系统提供了理论依据. 相似文献
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Optimized free-form phase mask for extension of depth of field in wavefront-coded imaging 总被引:1,自引:0,他引:1
To achieve a further extension of the depth of field in wavefront-coded imaging by reducing the impact of focus error in the optical transfer function, we propose the use of a free-form phase mask (FPM) instead of a conventional cubic phase mask (CPM). We optimized the shape of the FPM using the simulated annealing algorithm and confirmed that the optimized FPM provides a much larger focal tolerance and better final images than the CPM in the noise-free case. 相似文献