离轴反射式光学系统设计

提出通过光瞳和视场离轴,实现无中心遮拦的离轴反射式光学系统设计方法。在同轴三反射光学系统基础上,将光瞳和视场适当离轴,实现镜间遮拦的消除。分主镜或次镜为系统孔径光阑两种情况,导出同轴三反射光学系统初级像差公式和初始结构参数计算公式。由三反射系统成像性质,进一步总结无焦光路条件。根据设计理论计算离轴三反射系统初始结构,利用Zemax优化得到无中心遮拦的离轴三反射空间观测望远镜。入瞳320mm,视场(±0.3°)×(±0.6°),焦距1800mm。     

利用离焦光斑的离轴望远镜失调校正方法研究

离轴反射式望远镜主要应用于空间天文观测等领域。离轴两反望远镜的成像质量对镜片的失调敏感，且在工作环境下失调后使用激光干涉仪进行校准较为困难。针对这一难题，本文提出了一种利用系统对无穷远点目标的离焦光斑图并使用Swin-Transformer网络计算次镜横向失调量的方法。通过理论计算分析，可以避免多解问题的相机离焦位置，并利用仿真探究了不同离焦量对校正精度的影响，最后搭建实验平台进行验证，训练好的网络使用失调系统的一帧离焦光斑图便可进行失调量的估计。仿真分析与实验结果均验证了该方法的有效性，可实现工作环境中失调望远镜系统的高精度和快速校正。     

一种离轴使用的同轴三反射系统的设计和装调

本文设计了一种视场角为3.的离轴使用的同轴三反射系统,并从理论上分析了焦平面如何离焦补偿像差、反射镜倾斜和偏心之间的补偿关系.通过采取离焦、折镜的平动或转动、反射镜本身的偏心和倾斜相互补偿的方法,来补偿反射镜的装调误差.事实证明,比普通离轴三反射系统的装调容易实现,精确度高.     

高速风机振动分析和转子动平衡

某厂#2机组安装后试运行时风机轴振动就偏大,动平衡经过多次配重轴振动都不能降低到理想值.主要原因是风机转子制造时中间部位存在较大的质量偏心,而所加平衡重量在转子两端平衡孔内,工作转速下转子呈现出多阶振型叠加的复杂振型.按照挠性转子振型平衡理论,现场在只有两个加重面的条件下,不可能平衡二阶以上振型,风机轴振动就很难同时达到优良水平.     

五轴联动数控展成电解磨床原理与控制

为解决整体叶轮叶片型面的精加工难题,进行了五轴联动数控展成电解磨削整体叶轮的基础研究。根据数控展成电解磨削整体叶轮叶片型面这一加工方法的特点,在分析了数控展成电解磨削整体叶轮原理的基础上,对磨削系统的结构与运动进行了总体设计,提出了经济型多轴数控系统及其联动控制方法,建立了电解磨削非平行直纹展成曲面的数学模型,开发了五轴联动数控展成电解磨削自动数控编程系统,对航空发动机整体叶轮的叶片型面进行了电解磨削。五轴联动数控展成电解磨削技术为整体叶轮叶片型面的精加工提供了一种新的加工手段。     

二元光栅照明对光刻系统成象特性的影响

针对光刻系统分辨力和焦深的矛盾,详细研究了二元光栅照明对硅片上光强以及对光刻系统传输频率的影响,结果表明,二元光栅照明可显著提高光强的对比度,改善成象系统的频率传递函数,是一种比较理想的离轴照明技术。     

大口径多孔透镜离轴成像研究

设计并采用微细加工技术制作了直径D=50mm,特征尺寸为10μm的大口径多孔透镜(photon sieve).在一定的视场下采用数值计算和实验方法分析了其聚焦特性和MTF曲线,为克服多孔透镜一级衍射效率较低,成像质量受背景光干扰的影响,采用了同轴和离轴成像实验.实验结果与聚焦特性一致,两种实验方法得出的不同实验结果表明:离轴成像系统效果克服了同轴成像受0级背景光的影响,改善了像质,为很多一级衍射效率较低的衍射透镜成像提供一种新的成像方式.     

波分复用改善光纤传象束象质的导模分析

运用光纤导模（束缚模）理论和离散抽样理论分析了光纤象束象的质量，估算了决定波分复用象束系统象质的信息量Ｎ，Ｎ是到达象面的而且有与物场相位分布几乎相同的场模数，并估算了波分复用技术改善光纤象束系统象质的倍增率。     

全息图再现象研究

通过分析全息图记录的干涉条纹图样，指出对于二维全息图，一束再现光将产生两个对称于全息图面的物象，两束对称于全息图面的再现光将产生位形相同的物象；三维全息图的再现，象的对称性不变，但原物象的对称再现象有一定的弥散，对称光再现时，等亮度再现象出现在全息图转动一个角度之后，实验上制作了具有清晰透射彩虹全息象的象面反射全息图。     

基于CCD的航空相机自动检焦系统

要使航空相机获得高质量的图像,必须保证镜头的焦距和实际成像面的位置符合技术要求。提出了一种自动检测航空相机焦距和是否离焦（实际成像面的位置是否在焦深范围内）的系统,论述了系统的工作原理、硬件组成和软件设计。该系统采用平行光管产生检焦信息,利用CCD摄像头作光电转换器件接收图像,采用重心法处理数据,由光电线位移传感器和光栅数显表共同作用实现摄像头轴向的精确平移,从而能够确定相机的最佳成像位置和图像尺寸。最佳图像位置用来判断是否离焦,最佳图像尺寸用来计算焦距。使用该系统对航空相机镜头焦距的检测准确率达到99.87%、是否离焦的判断与试飞结果完全相同。     

Linear astigmatism of confocal off-axis reflective imaging systems and its elimination

Linear astigmatism of a confocal off-axis reflective imaging system when the object plane is tilted and located at a finite distance from the imaging system is derived. We show that linear astigmatism can be eliminated by proper configuration of the parent mirror axes in confocal off-axis two-mirror systems. The tilt angle of the image plane is also derived. The developed theory is verified by ray-tracing analysis of an example system.     

Michelson wide-field stellar interferometry: principles and experimental verification

A new interferometric technique for Michelson wide-field interferometry is presented that consists of a Michelson pupil-plane combination scheme in which a wide field of view can be achieved in one shot. This technique uses a stair-shaped mirror in the intermediate image plane of each telescope in the array, allowing for simultaneous correction of the differential delay for the on-axis and off-axis image positions. Experimental results in a laboratory setup show that it is possible to recover the fringes of on-axis and off-axis stars with an angular separation of 1 arc min simultaneously and with a similar contrast. This new technique represents a considerable extension of the field of view of an interferometer without the need for extra observation time.     

Performance evaluation of a Scheimpflug stereocamera for particle image velocimetry

We describe a novel stereocamera for particle image velocimetry (PIV) applications that incorporates the Scheimpflug condition that the object plane, lens plane, and image plane must be collinear. We examined the governing equations for this system using a computer-based sensitivity analysis to predict the accuracy of the in-plane and out-of-plane measurement. We evaluated the performance of the Scheimpflug PIV system with a three-dimensional uniform translation test. Results indicate that the Scheimpflug PIV stereocamera performs as expected. The larger off-axis angles possible with the Scheimpflug system can provide a higher accuracy in the out-of-plane component when compared with a translation PIV stereocamera.     

Performance of an Off-axis Holographic Lens in the Presence of Aberrations Induced by Construction-reconstruction Wavelength Shift: Extended Object Imaging

In this paper investigations have been carried out on the imaging of extended objects by an off-axis holographic lens operating at a wavelength different from its recording. Aberration balancing and correction techniques have been applied to improve the quality of imaging coherent as well as incoherent bar and edge objects. The light intensity distribution in the Gaussian image plane has been computed numerically and the results have been presented in graphical form. The image quality of the aberration-balanced holo-lens has been found to be comparable to that of the ideal holo-lens.     

Imaging of Extended Objects Using a Curved Holographic Lens Free From Spherical Aberration

Abstract

This paper evaluates the performance of an off-axis curved holographic lens using a numerical ray-tracing procedure. The hologram curvature has been suitably selected to eliminate spherical aberration. Light intensity distribution in the aberration spot observed at the Gaussian image plane has been evaluated for different object fields. The images of extended coherent and incoherent edge as well as bar objects have been computed and the results compared with that for the aberration-free case. All the results are illustrated in graphical form.     

Imaging of Extended Objects Using an Off-axis Holographic Lens

Abstract

The aim of this paper is to evaluate the performance of an off-axis holographic lens afflicted with third-order spherical aberration and coma using a numerical ray-tracing procedure. The light intensity distribution in the aberration spot observed at the Gaussian image plane has been evaluated for different amounts of coma and for a fixed value of spherical aberration. The images of both an extended coherent and an incoherent edge as well as bar objects have been computed and the results compared with the aberration-free case. All the results are illustrated in graphical form.     

Aberrations of Plane Grating Monochromators with Off-axis Paraboloidal Mirrors

Aberrations of plane grating monochromators with off-axis paraboloidal mirrors are studied analytically by the use of the light-path function and the Burch plate diagram extended to off-axis systems. Residual wave aberration of the third order becomes vanishingly small by compensation of two aberration terms in the U configuration, but remains fairly large by accumulation in the Z configuration. This explains an excellent image quality of the U configuration. It is shown that exact slit-image-curvature invariance with wavelength exists in the Z configuration but does not in the U configuration. A suitable value of the distance between the grating and off-axis paraboloidal mirror can be determined to eliminate certain residual aberration terms of the fourth order.     

Improved field scanner incorporating parabolic optics. Part 2: Experimental verification and potential for volume scanning

We investigated the experimental performance of an afocal scan engine employing two off-axis parabolic reflectors and it was found not to introduce astigmatism when compared to a freely propagated beam. The performance of the new afocal engine is very similar to an ideal single-mirror scan engine in terms of spot size and beam spot profile (or point spread function) and has an improved flatness of field over other two-dimensional laser scan engines. The parabolic scan engine is contrasted with a comparable spherical mirror arrangement and found to produce superior performance at the intermediate image plane when focused through a scan lens. Further modeling and experimentation point toward volume scanning applications. The significant performance improvement provided by this design, now verified experimentally, will result in superior image quality for fast scanning confocal and two-photon microscopy in particular.     

Transformation of Reference Spheres by an Aberration Free and Infinitely Large Optical System in the Fresnel Approximation

Imaging of a complex distribution by a thin lens is studied and generalized by analysing the imaging process of a complex distribution defined on an off-axis object sphere in an optical system. First, imaging of an object in an elementary system is considered, and then the considerations for the system being a combination of the elementary systems are presented. The general rule of reference spheres transformation is introduced. It is shown that complex distributions given on an off-axis object sphere are fully reconstructed on an image sphere of the system with a change of scale only. The relations between the parameters of the object and image spheres are determined. Some examples of the applications of the transforming rule are given.