Research on reflective zoom system with 3 mirrors

This paper uses the third-order aberration theory to design a reflective zoom optical system. The advantage of this method is that, by solving a set of Seidel aberration coefficient functions, it allows the designer to achieve the initial construction parameters of the optical system, i.e., radii of curvature and separations between mirrors, etc. In order to verify the accuracy of this method, a prototype of a coaxial zoom optical system with three mirrors is designed. This paper introduces the manufacturing process of the prototype in detail, describes the procedures of aligning and experimenting, and analyzes the experiment results in the end. In this way, the feasibility of this method is confirmed.     

三反射主动变焦系统设计

空间光学系统在对深空探测、监视、威胁侦测和对地高分辨率侦查等应用中,不仅需要能同时获得高分辨率和宽视场范围的变焦系统,还需要体积小、重量轻、低能耗及快速调焦的系统,传统机械变焦系统因需要复杂精确的机械运动控制而存在诸多问题.因而,基于主动光学理论,将主动光学元件应用到成像系统中,提出了通过某个或某几个光学元件的曲率半径变化实现系统焦距变化的理论.根据初级像差理论和系统的外形尺寸,研究了系统主动变焦原理,确定了初级像差方程组的约束条件,求解共轴主动变焦系统的初始结构参数,借助ZEMAX软件进行优化设计,设计了一个由静止的主镜、曲率半径作为变量的次镜和三镜、无光焦度的平面镜组成的三反射主动变焦系统.由于该共轴三反射主动变焦系统存在两次遮光,会影响系统像面能量的接收,因此,指出对共轴系统进行无遮拦离轴优化设计的必要性,讨论了离轴系统设计理论,并设计了离轴三反射主动变焦系统.     

Design of Plane-Symmetric Low <Emphasis Type="Italic">F</Emphasis>-number Reflective System Based on Perturbation Aberration Model

All-reflective optical systems have theoretically no chromatic aberration and are suitable for wide spectral application, but co-axial reflective systems are difficult to design as low F-number optical systems. In this paper, the aberration of plane-symmetric optical systems with low F-number is analyzed based on the wavefront derived from optical path length. Up to third-order aberrations are classified into three categories by their characteristics. The reduction method of the dominant aberration, astigmatism-like aberration, is proposed. In the method, the Gauss image plane is modeled by means of a simplified mirror surface with third-order approximation. Because the system is plane-symmetric, symmetric cross section and asymmetric cross section are modelled differently. The design example of a three-mirror system with F/2 is shown.     

Third-order aberration analysis of an off-axial optical system

The aberration theory applied to co-axial optical systems is extended to off-axial systems, for which third-order aberration coefficients are considered. The derived aberrations are analyzed using three-dimensional ray bundles, spot diagrams, and image charts, and classified in relation to the system symmetry. This theory is very useful for optical designers, allowing them to clarify the relationship between the structures of off-axial optical systems and the corresponding off-axial aberrations.     

Third-order aberration analysis of tilted-pupil optical systems

The aberration field of an optical system with a tilted pupil is explored through expanding the vector expressions of the third-order wavefront aberrations. First, the vector forms of the wavefront aberrations are modified to obtain the aberration expressions with the pupil tilted; full field displays of coma and astigmatism in this situation are given. Then, the third-order aberration formulas with the pupil decentered and tilted simultaneously are derived and discussed. Finally, an example is taken to certify the validity of aberration distribution properties.     

Design of Double Cassegrain reflective mirrors for optical system of IR cameras

IR optical systems such as Petzval doublet refractive lenses or Cassegrain reflective mirrors are either expensive or poor in image quality. Taking advantage of the low cost of reflective mirrors, here we present an optical design of Double Cassegrain reflective mirrors consisting of two sets of Cassegrain reflectors facing each other symmetrically. This symmetry also cancels many aberrations besides the chromatic aberration-free nature of reflective mirrors. Design results show that this system is better than Cassegrain reflectors in aberration correction and image resolution, but cheaper than Petzval doublet refractive lenses systems in price. IR cameras with this optical system could be widely used for body temperature measurement and security check.     

面对称光学系统的初级波像差理论研究

非旋转轴对称光学系统波像差理论的建立有利于理解旋转 轴对称光学系统的装调误差和离轴三反射光学系统等非旋转轴对称光学系统的选型设计. 本文利用旋转轴对称球面光学系统的全口径初级波像差理论推导了子孔径面对称光学系统的初级波像差分布公式, 证明了面对称光学系统中的节点像差理论, 即除球差外的所有初级像差的零值节点偏离视场中心, 而不再是视场的旋转对称函数; 并首次阐述了多零值节点初级非对称像差产生的根源和变化特性. 该理论可以有效指导非对称光学系统初始结构的选择和优化设计过程. 关键词： 面对称 像差 几何光学     

偏心和倾斜光学系统的像差特性

运用一种新的分析偏心和倾斜光学系统初级像差特性的方法—矢量像差理论,分析了具有较大交叉倾斜角的平行平板光学系统和具有较大倾斜角的光楔光学系统的像差特性.通过ZEMAX光学设计软件像差分析功能中的垂轴像差曲线、场曲曲线和点列图加以比较,两者非常吻合,证明该理论可以对具有较大倾斜元件的非共轴光学系统设计起指导作用.     

激光靶心冲击波观测镜折反式光学系统设计

设计了一种激光靶心冲击波观测镜的光学系统.用反射式光学系统代替折射式光学系统,解决了普通玻璃在200 nm端透过率较低的问题.反射镜不引入色差,有利于系统在200~800 nm谱段消色差.为消系统轴外像差,反射系统选型为对称式.反射镜全部采用球面镜,为消反射镜以及平板玻璃窗带入的球差,引入校正镜(材料JGS1),在满足要求的条件下,控制折射镜的厚度,使系统色差满足瑞利判据的色差允差,得到了良好的成像质量.     

Aberrations of plane-symmetric multi-element optical systems

Based on a recently developed aberration theory of plane-symmetric grating systems, its aberration coefficients are firstly extended to be applicable to the plane-symmetric refractive optical surface. To justify the linear approximation of aperture ray in a multi-element system, the ray aberrations of double-element systems with the third-order accuracy of aperture ray are derived and expressed as the form of wave aberrations. The numerical comparisons are then made between the ray tracing, the aberration expressions with the linear and with third-order accuracy of the aperture ray. Moreover, the modifications of the wave and ray aberrations are discussed in the paper when the position of the principal ray changes.     

新型离轴反射变焦距光学系统的多视场检测方法

基于对离轴反射变焦距光学系统进行计算机辅助装调研究, 需要检测离轴反射变焦距系统各个视场的波像差, 除零度视场外, 获得包括其他视场的波像差有助于提高计算机辅助装调的准确性, 但是目前已有的波像差检测方法往往只能获得系统零度视场的波像差. 本文针对这个难题提出了一种检测离轴反射变焦距光学系统各个视场波像差的方法, 并应用于离轴三反变焦距光学系统的各视场波像差仿真检测. 该方法在传统自准直干涉法的基础上进行改进, 关键在于采用变形镜代替扫描的平面镜, 并采用夏克-哈特曼波前传感器代替干涉仪, 配合精确标定的激光器光源阵列, 可以实现对离轴三反变焦距光学系统的多视场波像差同时检测. 由理论分析和仿真模拟得出, 该系统在视场(0°, 3°), (0°, 4.2°), (0°, 5.5°), (0°, 7°), (0°, 9.8°), (0°, 14°)处经过变形镜补偿后的剩余波像差的RMS值分别为0.00039λ, 0.00075λ, 0.0024λ, 0.00017λ, 0.00053λ, 0.0057λ, 分析仿真结果表明此检测方案是可行的, 且适用于离轴反射变焦距系统的计算机辅助装调技术的研究.     

Optimization of 350× optical zoom lens with diffractive optical element

Through researching and validating, a set of optical designs using a diffractive optical element (DOE) and optimization process has been derived in this paper. We put forward a set of theories to solve the numerous quality issues in imaging and applied it to an optical design. For an optical design to be successful, it must comply with the standards of the optical system. Optical designers must also take into consideration imaging quality, wherein the most influential aspects are chromatic aberration and monochromatic aberration. We complied with systemic standards such as effective focal length and total system length. Diffractive Optical Element, based on the theory of wave phase difference, takes advantage of negative Abbe number, which might significantly eliminate chromatic aberrations of optics. Following the advanced technology applied to micro lens and etching process, precisely made micro DOE element now is possible to be manufactured in a large number. A 350× zoom lens with DOE is demonstrated in the proposal. The results show that regardless of whether chromatic aberration is axial or longitudinal, issues concerning the optical lens's chromatic aberration could be significantly reduced.     

Different algebraic method for computing the high-order aberrations of practical combined focusing-deflection systems

Differential algebraic (DA) method is an effective technique in computer numerical analysis. It implements conveniently differentiation up to arbitrary high order, based on the nonstandard analysis. Some complicated nonlinear dynamics problem including high-order aberrations of electron optical systems can be solved effectively by mapping properties of DA quantities. However, the existing study applying DA method to the practical system is limited to simple electron lenses. In this paper, the application of DA method is extended to practical combined focusing-deflection systems, and the aberrations up to fifth order are calculated. The electric and magnetic fields of the electron lenses and deflectors, which are computed by finite element method (FEM) or finite difference method (FDM), are in the form of discrete arrays. Local analytical expressions for electric and magnetic field quantities are constructed from these arrays for arbitrary place where electron is traced in DA computation. Thus the developed DA method is applicable for engineering design and computing problem. Based on the study of the expressions and the structure of the aberration coefficients for the fifth-order aberrations of the combined focusing-deflection system and the local analytic expression of the practical electromagnetic field, correlative computer software was developed, whose interface is convenient to calculate the high-order aberrations of the practical systems. The new DA method and software are tested with a uniform magnetic field deflection having an analytic solution. And the results show that the accuracy is sufficiently high, only limited by machine precision. Finally, as an example, a practical combined magnetic focusing and magnetic deflection system is analyzed and discussed.     

正支共焦非稳腔的离焦像差特性

 正支共焦非稳腔在出光过程中易受环境扰动而造成腔长失调，易受热积累影响而使腔镜变形，从而使输出光束产生离焦像差和部分其它像差。为了实现对离焦像差的校正，针对不同的产生原因，提出了2种离焦像差特性分析方法：一为腔镜相对位置失调引起的离焦像差特性理论分析方法，它是另一种分析方法的基础；二为腔镜变形引起的等效腔长变化导致的离焦像差特性分析方法，它是实际激光器中的主要分析方法。得到了离焦像差与腔长的特性关系和离焦像差与腔镜变形量之间的特性关系。研究表明：腔长改变和腔镜变形对离焦像差的影响本质是一样的，都是改变了谐振腔的共焦点位置；腔长改变或腔镜矢高变化与离焦像差都成近似的线性关系。实验验证了离焦像差特性分析方法的有效性，最后指出离焦像差特性可作为激光器中离焦像差动态补偿的有效依据。     

磁透镜与偏转器的复合系统的电子光学性质和象差理论

本文研究了旋转对称磁透镜和磁偏转器的复合系统,给出了场和轨迹的普遍表达式。利用向量形式来描写电子轨迹,讨论了高斯光学性质。运用变分原理(费马原理)计算了三级象差,得出了复合系统普遍的象差公式。它们以矩阵的形式表出,形式简洁,便于进行数值计算。本文的结果具有较大的普遍性,概括了文献上关于偏转象差的已有结果,并对复合系统作了较完整的论述和严格的计算,因而可以广泛地研究各种电子束管和电子光学仪器的偏转象差。     

新型折反射式椭球形整流罩光学系统的设计

提出了一种可用于指导非旋转对称、折反射式光学系统设计的Wasserman-Wolf曲面设计方法,并将其用于设计椭球形整流罩光学系统,得到的系统具有结构尺寸小的优点。利用最小二乘拟合的方法使系统初始结构兼顾各个扫描视场的像差校正需求,克服了以往只针对零视场计算校正元件初始参数致使扩展至整个扫描视场时系统评价函数难以收敛的弊端。同时,从平面对称的矢量像差理论出发,分析了平面对称反射镜的像差特性,阐述了在不同扫描视场中,利用反射镜倾斜来进行动态像差补偿的原理。设计了一套工作波段为中波红外的椭球形整流罩光学系统,该系统的调制传递函数(MTF)在整个扫描视场内接近衍射极限。     

用高斯光学和三级像差理论求变焦距物镜的初始解

ZEMAX和CODE V等光学设计软件,虽然有很强的优化功能,但如果想得到好的设计结果,初始解的选择至关重要。求初始解的普遍做法是,将已有的光学系统或其中某一个组元拿来进行缩放。这种办法带有盲目性。另一种方法就是利用高斯光学和三级像差理论求变焦距物镜的初始解。这一方法有助于创新设计,但却很少被应用。本文介绍了作者在运用这一方法过程中产生的观点、理念、经验和成果。本文通过一个十倍变焦距物镜设计实例,详细介绍了求初始解的过程,为了验证该初始解的效果,还用ZEMAX进行了像差优化。为了增加说服力,设计过程的每一步,都给出了具体的数据,包括经ZEMAX优化得到的最后结果。     

Non-approximate method for designing annular field of two-mirror concentric system

Annular field aberrations of a three-reflection concentric system,which are composed of two spherical mirrors,are analyzed.An annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image plane.Aberrations are determined by the object height and aperture angle.In this letter,the general expression of the system aberration is derived using the geometric method,and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture angles.The closer to 0.5（the ratio of the radius of convex mirror to the radius of concave mirror）is,the smaller the system aberration is.The examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.     

利用镜面形变实现共轴折反射式变焦光学系统设计

在光学系统中加入2个或多个可变光学元件,保持光学元件位置不变,通过微调装置改变这些可变光学元件的焦距使得整个光学系统的有效焦距发生变化。基于该设计思想,结合卡塞格林(Cassegrain)反射式望远镜结构模式,使用ZEMAX光学设计软件设计了焦距为1 600 mm～800 mm,视场0.6°～1.2°的变焦系统,整个系统由2个可变形反射面、1个平面反射面和1个透镜组成,主要通过主镜和次镜面型曲率(可变形镜DMs,Deformable Mirrors)以及入瞳直径的变化实现系统变焦。设计结果表明:系统在空间频率16 lp/mm处调制传递函数大于0.75,最大均方根弥散斑半径均小于探测元尺寸,满足成像要求。