基于自然导引星的自适应光学系统非等晕性分析

采用波前各阶zernike成分孔径滤波函数方法,推导了当观测目标与信标不在同一方向时所产生的非等晕误差的表达式,同时利用该表达式进行了对自适应光学系统倾斜校正后的波前残余误差数值模拟.此外还首次对天文干涉仪中大气湍流活塞效应引起的活塞角非等晕误差进行了研究分析,为以后实际利用自适应光学校正工作提供理论参考.     

基于PCl-Express高速图像采集卡对扩展源大气倾斜量的实时补偿

为能够实时补偿大气湍流对月球激光测距带来的渡前倾斜量误差,采用相关跟踪自适应光学系统,并根据其大计算量、高实时性的要求,创新地设计了基于PCI-Express高速图像采集卡及其硬实时操作系统驱动程序,完成对扩展源目标大气倾斜量的实时补偿.详细介绍了整体系统的软硬件设计,给出了一种PCI-Express高速图像采集卡设计结果及其RTAI实时驱动程序的软件设计结果,完成了进一步提高图像传输速度,减小相关跟踪系统系统延迟,提高系统响应带宽的目标,最终实现了图像数据的实时传输(≤28 μS)及波前倾斜量的实时补偿(≤348 μS).     

自适应光学应用于月球激光测距中视场旋转对大气波前倾斜量提取的影响

自适应光学技术应用于月球激光测距试验中需要实时针对月面扩展源进行大气波前倾斜量的提取,望远镜在跟踪月亮的过程中存在月面本身相对望远镜的物方视场的旋转以及望远镜自身的运动所引起的像方视场的旋转,本文讨论了望远镜物方视场及像方视场旋转的规律以及其对大气波前倾斜量提取的影响。     

恒星干涉仪中的高速倾斜镜应用研究

在恒星干涉仪中,高速倾斜镜(Fast-steering mirror,FSM)因分辨率高、响应频率快等特点被广泛应用于校正大气湍流、仪器内部振动等引起的波前倾斜.一方面,针对倾斜镜本身在加工、装调中引入的镜面与触动器偏转轴不共面等误差进行系统分析,通过数值方法研究了上述因素在倾斜镜工作时产生的附加光程差(Optical Path Difference,OPD),并讨论了该光程差对恒星干涉仪条纹跟踪精度的影响;另一方面,两臂光束之间的平行度误差是造成干涉条纹可见度损失的主要因素之一,通过分析大气扰动引起的波前倾斜对条纹可见度的影响,提出了一种基于单一阵列探测器、简单高效的星光平行度实时校正方案,并结合室内实验论证了该方案的可行性.实验结果表明:经高速倾斜镜校正后的星光方向平行度初步满足了恒星干涉仪系统对波前倾斜的需求.     

人造导引星自适应光学的倾斜决定问题

本文从Zernike多项式出发 ,推导了激光导引星自适应光学倾斜校正的非等晕性方差 ,以其方差 1rad2 为判据 ,导出了倾斜等晕角的表达式 ,得出了与Parenti和Sasiela推导的相同的结果     

斑点图的重心与波前倾斜

论述了斑点图重心与瞬时波前倾斜的关系,证明了斑点图重心位置与瞬时波前倾斜的一致性,这种一致性无论光瞳孔径是否大于大气相干长度均是成立的.这一结论并未严格受限于近场近似条件,结论的一个重要推论是:用重心对准的位移叠加法对斑点图进行统计后所得到的传递函数就是大气望远镜综合系统的平均短曝光传递函数,该推论对于自适应光学和高分辨率图像重建技术均具有非常重要的意义.     

人造导引星自适应光学的倾斜决定问题

本从Ｚｅｒｎｉｋｅ多项多出发，推导了激光导引星自适应光学倾斜校正的非等晕性方差，以其方差１ｒａｄ＾２为判据，导出了倾斜等晕角的表达式，得出了与Ｐａｒｅｎｔｉ和Ｓａｓｉｅｌａ推导的相同的结果。     

基于四棱锥传感器的波前检测仿真设计

波前检测是天文望远镜自适应光学中的重要环节。四棱锥作为一种新型的波前检测元件,与其他传统的波前传感器相比,具有较高的灵敏度。特别是对于光干涉或拼接镜面望远镜而言,四棱锥波前传感器能够被用来检测子望远镜或子镜面之间的相对光程差,从而为干涉(或共相)的实现提供有效的检测信号。在分析四棱锥波前检测原理的基础上,阐述了单孔径条件下波前倾斜检测及双孔径干涉条件下相对光程差检测的软件仿真设计和阶段性成果,并简述了下一阶段的研究计划。     

空间目标跟踪的概率数据关联方法

在空间目标的光学观测中,由于跟踪波门内多个量测事件频发,导致跟踪量测的不确定,降低自动跟踪精度引起跟踪不稳.结合Kalman滤波和概率数据关联算法,实现了空间目标自适应跟踪.方法通过Kalman滤波预测确定关联区域,采用概率数据关联技术获得等效量测作为Kalman滤波的有效馈源.实验表明:方法可以有效地提高自动跟踪精度,改善空间目标自动跟踪鲁棒性.     

基于迭代分形法的大气波前仿真

大口径望远镜受大气湍流的影响,光学分辨率远远小于其自身光路所决定的衍射极限。为了相应的自适应光学系统设计,首先有必要对大气波动进行仿真以提供环境数据。通常的大气波前仿真方法需要通过计算结构函数,得到功率谱函数,进而得到仿真波前,但该方法存在计算速度慢,中间变量存储空间大的问题,给大口径望远镜或者长时间仿真带来很大不便。介绍了一种可行的基于迭代分形法的波前仿真方法,复杂度达到O（N）,可以大大提高波前仿真的速度。     

Curvature Wavefront Sensor For Solar Adaptive Optics

Active or adaptive optics often require the ability to characterize wavefront aberrations using natural extended sources. The task becomes especially challenging when dealing with widely extended sources such as the solar granulation. We propose a new approach based on the processing of oppositely defocused images. This method, which is a generalization of a technique known as curvature sensing, derives the wavefront curvature from the difference between two oppositely defocused images and determines the second momenta of the point spread function. The proposed method measures the wavefront aberration from the images themselves, requires little computational resources, is fast enough to be used in a real-time adaptive optics system and is particularly adapted to random patterns such as solar granulation or spot penumbras whose morphology evolves during the observation. We envision the application of the method to real-time seeing compensation in solar astronomical telescopes, and to the correction of optical system aberrations in remote sensing instrumentation. This effort is directed towards building a curvature sensor for the real-time applications.     

2.16m望远镜红外自适应光学系统的误差和性能分析

在自适应光学系统中，波前探测器的噪声、未完全补偿湍流所引起的误差以及变形镜的拟合误差是主要的误差源．本文针对已经建立的2．16m望远镜红外自适应光学系统，从伺服控制系统的角度分析了该系统的闭环噪声、大气湍流引起的误差以及该系统的闭环总体误差．该系统的闭环总体误差是光强及系统闭环带宽的函数．本文还分析了该系统的有效性以及对大气湍流不同改善程度情况下光强与闭环带宽的关系．并在此基础上给出了该系统的最佳带宽选取及系统的极限工作星等．     

Evaluation of a Wavefront Sensing Concept for a Full Solar Disk Adaptive Optics System

Solar scintillations were investigated as a method of detecting seeing-dependent wavefront curvature variations for solar adaptive optics. The method is applicable to full-disk averaged, adaptive corrections of large-scale near-field seeing distortions. As a test case, seeing measurements were carried out on a single small adaptive mirror, representing one element of what would be a large multielement adaptive array. All observations showed a greater than 5× reduction of seeing distortions as a result of this wavefront correction.     

Improvements on the optical differentiation wavefront sensor

We describe a novel concept for high-resolution wavefront sensing based on the optical differentiation wavefront sensor (OD). It keeps the advantages of high resolution, adjustable dynamic range, ability to work with polychromatic sources and, in addition, it achieves good performance in wavefront reconstruction when the field is perturbed by scintillation. Moreover, this new concept can be used as multi-object wavefront sensor in multiconjugate adaptive optics systems. It is able to provide high resolution and high sampling operation, which is of great interest for the projected extreme adaptive optics systems for large telescopes.     

太阳方位的自动获取及实时跟踪系统的设计

针对以往太阳方位手动计算复杂易错且不具备实时性的缺点设计了一套实时跟踪系统。该系统采用微芯公司生产的dsPIC作为核心处理器,具有处理速度快、功耗低的优点。系统结合了HMC3200电子罗盘与高精度视频方位仪,能够实时获取装置的位置指向和实时图像加以观察,使用的太阳方位算法简洁可操作性强、精度高,运行结果显示能满足实时追踪的效果。     

Prospects for the GLAS Rayleigh laser beacon on the 4.2-m WHT

The scientific exploitation of adaptive optics (AO) with natural guide stars is severely constrained by the limited presence of bright guide stars for wavefront sensing. Use of a laser beam as an alternative means to provide a source for wavefront sensing has the potential of drastically improving the sky coverage for AO. For this reason at the 4.2-m William Herschel Telescope a project was started to develop a Rayleigh laser beacon to work together with the existing NAOMI adaptive optics instrumentation and the OASIS integral field spectrograph. This paper presents the rationale for this development, highlights some of the technical aspects, and gives some expected performance measures.     

Pseudo-infinite guide stars for multi-conjugated adaptive optics on extremely large telescopes

We introduce a novel concept to sense the wavefront for adaptive optics purposes in astronomy using a conventional laser beacon. The concept we describe involves treating the light scattered in the mesospheric sodium layer as if it comes from multiple rings located at infinity. Such a concept resembles an inverse Bessel beam and is particularly suitable for multi-conjugated adaptive optics on extremely large telescopes. In fact, as the sensing process uses light apparently coming from infinity, some problems linked to the finite distance and vertical extent of the guide source are solved. Since such a technique is able to sense a wavefront solely in the radial direction, we propose furthermore a novel wavefront sensor by combining the inverse Bessel beam approach with the recently introduced z -invariant technique for a pseudo-infinite guide star sensor.     

基于1.2m望远镜自适应光学系统激光信标转盘式机械快门的研究

基于激光信标发射和接收共光路系统中探测器受杂散光影响的关键问题,设计了一种新型转盘式机械快门装置,对光信号进行高频率开关控制,从而对自适应光学系统的波前探测器起到彻底保护作用.设计时,分析了瑞利信标的采样厚度以及快门开关与脉冲激光器的发射、探测器探测时间的时序控制.     

基于1．2m望远镜白适应光学系统激光信标转盘式机械快门的研究

基于激光信标发射和接收共光路系统中探测器受杂散光影响的关键问题,设计了一种新型转盘式机械快门装置,对光信号进行高频率开关控制,从而对自适应光学系统的波前探测器起到彻底保护作用。设计时,分析了瑞利信标的采样厚度以及快门开关与脉冲激光器的发射、探测器探测时间的时序控制。