部分相干光场结构信息经有象差光学系统传递的机理

本文讨论了部分相干光场经光学系统成象之后在象面上的自由度;利用成象系统积分方程和照明系统积分方程两步积分方程的共同作用,解释了部分相干光场自由度经光学系统传递的机理;同时得到光学系统象差不影响自由度的结论.     

一般光学系统图象自由度几个问题的研究

本文通过对成象过程的一般性讨论,指出图象自由度(DOF)并不受波象差(相干光成象时)或者PTF(非相干光成象时)的影响,并且提出了处理一般光学系统信息量问题的若干方法。     

穆斯堡尔成象技术

通常的穆斯堡尔谱给出的是在样品范围内经空间积分的微观结构信息．近年来提出二类基于穆斯堡尔谱学的成象方法，用以确定物相的空间分布，达到实现空间分辨可达微米量级的穆斯堡尔成象．它为固体物理、材料科学、矿物学等提供一种新手段．该文介绍这个刚开始发展的新领域的现状和前景．     

光电成象系统中的积分抽样效应

光电成象系统涉及空间和时间上的积分和抽样.本文从理论上研究了光电成象系统中的抽样的空间积分效应和前置光学滤波的影响.结果发现前置光学滤波可以等效为抽样象元的空间积分抽样效应.这一原理对设计光电成象系统具有指导意义.利用这一原理也可以改善光电成象系统获取图象的质量.     

编码成象技术用于提高针孔成象空间分辨率

本文采用编码成象技术处理针孔成象,提高其空间分辨率.采用反投影解码技术,对针孔成象的分辨率进行了计算,结果表明,可将10μm的针孔成象空间分辨率提高到3μm左右.最后对字母“C”图象进行模拟计算,经反演后,可以得到与原图象相近的图象.     

布阵声成象的两种处理方式

本文利用Hilbert变换建立复信号与实信号间的关系,给出复振幅与实信号的关系.在此基础上从同一公式导出了处理顺序不同的两种成象方式,一是时间处理在前,空间处理在后的方式——全息处理方式;另一是空间处理在前,时间处理在后的方式.在全息处理方式中还导出一维线阵时间扫描的成象方法.在空间处理在前的方式中导出三种可能的形式,特别描述了空间序率滤波器成象.还将全息成象推广到综合孔径,引出了三个不同的处理方式.最后对两种成象方式进行比较.     

磁共振成象新进展

磁共振成象(MRI)已经成为生命科学研究和医疗诊断的有力手段，因此荣获2003年诺贝尔生理学或医学奖．文章概述了磁共振成象的新近进展，包括医疗成象、脑功能成象、显微成象、活体磁共振波谱等方面．     

循环流化床固体分布的层析成象测量

电容层析成象是９０年代以来快速发展的多相流研究方法．本文报道应用电容层析成象对循环流化床底部浓度分布的测量研究．本研究在国际上首先实现了矩形流道中的层析成象测量技术．成象中采用了迭代成象算法,明显地提高了复杂流动情况下的成象质量．测量结果显示出循环流化床底部多种气泡和固体分布情况,表明其流态与鼓泡床相吻合．     

核磁共振成象的当前进展与评述

简短地介绍了核磁共振成象的基本原理,并与传统的核磁共振波谱学进行了比较。列举了当前核磁共振成象研究工作的各个方面,并给出了研究工作体系表。对其中关于快速成象,提高空间分辨率以及对比度增强剂等问题做了重点评述。详细评述了化学位移成象及波谱成象的发展。对空间定域波谱学的发生、它与核磁共振成象及核磁共振波谱学的关系以及将来的发展等问题,提出了作者的观点。     

用成象自由度评价光学系统的信息量

本文探讨了一般光学系统的成象自由度传递及信息量问题,计算了不同信噪比σ₀/σ_n下一维相干光和非相干光照明的衍射受限系统的有效自由度数N_off,并与经典分辨率理论的象素数作了比较。     

激光光刻中焦深概念的新探讨

焦深大小将直接影响激光光刻加工的最细线宽和线条的边缘倾角从而影响被加工器件性能.传统的几何光学焦深概念对有光刻胶存在时的激光光刻已不适用.本文导出了会聚的高斯光束用于激光光刻时在光刻胶内的光场近似分布形式,由此可判断出光刻胶对光刻线条的分辨率和焦深的影响,从而提出激光光刻时焦深的新概念和估算.     

数字全息成像系统的景深和焦深分析

根据全息理论,分析了数字全息成像系统的景深和焦深.针对数字全息不同的记录光路结构,分别给出了焦深的近似表达式.结果表明：数字全息系统的景深和焦深不仅与记录波长以及记录时的数值孔径有关,还与记录时参考光波的偏置情况有关;在记录距离和CCD参量一定的条件下,离轴无透镜傅里叶变换全息对称偏置下的焦深比非对称偏置下的稍小;显微成像情况下离轴无透镜傅里叶变换全息系统的焦深大于同轴菲涅耳数字全息系统的焦深,计算机模拟表明了结果的正确性.     

手机成像系统的波前相位编码板光学特性的优化

设计了基于波前相位编码板的轻薄手机镜头,原始成像系统的焦深大小是0.017 mm,使用立方相位编码板,采用基于斯特列尔比的相位板优化方法,保持了在不同离焦位置成像系统MTF的稳定性,最终成像系统设计焦深达到0.136 mm,焦深扩展了8倍,经过Zemax软件仿真,验证了景深延拓的效果。设计结果表明,使用相位编码板即可增大定焦距手机系统的景深,使得系统结构紧凑,又克服了视场效应。     

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.     

用位相板实现景深延拓的原理与模拟实验研究

对波前编码技术实现景深延拓的原理进行了研究,分析了波前编码系统成像对离焦不敏感的原因,得到了波前编码光学系统景深延拓扩展率公式,发现了景深延拓扩展率与位相板参量的关系.利用Zemax设计了波前编码光学系统,用Matlab进行了成像模拟实验,实验结果表明,波前编码系统能提高传统光学系统的景深,提高的倍数由三次相位板的相位常量决定.     

Bessel beam spectral-domain high-resolution optical coherence tomography with micro-optic axicon providing extended focusing range

Endoscopic imaging in tubular structures, such as the tracheobronchial tree, could benefit from imaging optics with an extended depth of focus (DOF) to accommodate the varying sizes of tubular structures across patients and along the tree within the same patient. Yet the extended DOF needs to be accomplished without sacrificing resolution while maintaining sufficient sensitivity and speed of imaging. In this Letter, we report on the measured resolution and sensitivity achieved with a custom-made micro-optic axicon lens designed to theoretically achieve an 8 mm DOF. A measured invariant resolution of approximately 8 microm is demonstrated across a 4 mm measured DOF using the micro-optic axicon while achieving an invariant sensitivity of approximately 80 dB with a 25 mW input power. Double-pass Bessel beam spectral-domain optical coherence tomography with an axicon micro-optic lens (i.e., <1 mm in diameter) is, for the first time to our knowledge, demonstrated in a biological sample demonstrating invariant resolution and signal-to-noise ratio across a 4 mm measured DOF, which is compared to Gaussian beam imaging.     

Formation of sub-half-wavelength focal spot with ultra long depth of focus

We theoretically demonstrate the creation of sub-wavelength focal spot with ultra long depth of focus (DOF) non-diffracting. To achieve a sub-half-wavelength focal spot (0.4λ) with modulation, extended DOF (over 9.5λ) in vacuum, an integration of amplitude phase encoding, cylindrical polarization and the combination of dual-beams is utilized. Further analysis also predicts that a flattop intensity distribution along z axis can be observed around the ideal focus point.     

五自由度自由曲面加工系统及其CAM设计

研究横式结构数控电火花线切割机床,用于自由曲面型面的超精密制造。基于机器人运动学理论建立五自由度机床坐标系统并推导出数学模型。实施加工过程中运动轴位移量补偿计算,开发了精密加工系统的计算机辅助制造功能。解决了从坐标点到各轴位移量的转换计算问题。     

Deterministic and complete hyperentangled Bell states analysis assisted by frequency and time interval degrees of freedom

Hyperentangled Bell states analysis (HBSA) is an essential building block for certain hyper-parallel quantum information processing. We propose a complete and deterministic HBSA scheme encoded in spatial and polarization degrees of freedom (DOFs) of two-photon system assisted by a fixed frequency-based entanglement and a time interval DOF. The parity information the spatial-based and polarization-based hyper-entanglement can be distinguished by the distinct time intervals of the photon pairs, and the phase information can be distinguished by the detection signature. Compared with previous schemes, the number of the auxiliary entanglements is reduced from two to one by introducing time interval DOF. Moreover, the additional frequency and time interval DOFs suffer less from the collective channel noise.