自适应光学系统的多激光导星波前重构算法研究
发布时间：2018-08-09 19:52
【摘要】：通常自适应光学系统是将被成像目标的光能量分出60%以上用于波前探测。此外自适应光学系统通常所使用的哈特曼波前探测器,是用子孔径将望远镜接收波前分割为直径只有10cm左右的子波前,通过一一探测子光束的波前倾斜来重构望远镜接收的整体波前,此处限定了子孔径接收的光能量只相当10cm口径的望远镜,因此传统的自适应光学系统能够校正成像的极限星等只有5星等!利用激光导星来探测波前,不仅能提高成像目标的极限星等,而且使自适应光学系统能对分布在大视场中的多目标同时成像。但是,激光导星能发射的高度相对被成像目标来说低得多,导致探测的波前缺失信息产生非等晕误差。因此采用多个导星弥补波前信息缺失、进行波前的信息融合与重构是导星探测技术的关键。本论文首先按照普遍认可的Hufnagel-Valley的大气折射率结构模型,以大气折射率垂直分布函数为光通道分层权重分配依据,采用高度各阶原点矩算法计算各层等效面的高度位置,得出:大气湍流对光波前有影响的通道为从地面到15km高度处,集中了全部大气湍流的99.3%,也可以近似认为从地面到8km高度处,其中集中了全部大气湍流的96%,;可将15km大气通道分为近似等密度的三层或将8km大气通道分为近似等密度的二层:第一层从地面到1.65km,等效面高度为0.15km,湍流强度权重为88.2%;第二层从1.65km到8.00km,等效面高度为3.78km,湍流强度权重为7.1%;第三层从8.00km到15km,等效面高度为11.20km,湍流强度权重为4.0%。提出一种符合大气湍流的空间统计特性和时间统计特性的动态相位屏生成方法,基于该方法建立了大气湍流仿真程序,为波前重构算法的验证和分析提供了基础。提出在地基望远镜的接收平面上多颗瑞利导星波前信号的平面加权波前重构方法。基于相位结构函数,分别以每颗导星在地面的投影位置为中心,计算该导星的波前探测信号在望远镜接收口径的径向与方位上的权重分配函数,进行多颗导星波面的加权融合,完成成像目标的波前重构。针对望远镜口径为1.25m,大气相干长度为10cm,采用5颗呈十字形排布、外接圆与望远镜口径重合、高度为10km的瑞利导星,用平面加权算法模拟校正轴上目标成像时,不考虑校正误差的斯特列尔比理论上能够达到0.49。进一步考虑10km高度以上大气层的未采样误差,计算得到上层未采样误差为0.57rad,这样波前探测的总误差rms值增至1.02rad,换算为系统的斯特列尔比仍然可以达到0.35,说明五颗10km高度的瑞利导星能够满足实用要求。搭建了光学平台上的检验光学系统,实验结果与理论值吻合,证明平面加权波前重构的算法精度足够高。对于4米以上大口径望远镜的多层共轭自适应光学成像的应用,须使用发射高度90km的钠导星,采用广义tikhonov正则化的zernike模式分层解析重构波前算法,避免投影矩阵条件数过大的问题。当望远镜口径为8m,大气相干长度为12cm,采用3颗90km高度的钠激光导星时,广义tikhonov正则化的zernike模式分层解析波前重构算法在1角分视场内的平均误差为0.68rad,其相应的斯特列尔比达到0.63,为1.26倍衍射极限分辨能力。多层共轭自适应光学系统中,钠导星数量在3-5颗为宜,校正器数量在2-3个为宜,进一步增加导星数量和校正器的数量对自适应系统性能的提高有限。导星的最佳分布为:2颗导星为直线分布,导星对应视场中心张角为15.7″、三颗导星为正三角形分布,导星对应视场中心张角为21.5″、四颗导星为正方形分布,导星对应视场中心张角为23.5″、五颗导星为正五边形分布,导星对应视场中心张角为27.4″。最佳的校正器共轭高度只与大气湍流强度的垂直分布有关,使用两个校正器时,其最佳共轭高度为0km和10km;使用三个校正器时,其最佳共轭高度为0km、2km和11km。本文提出的波前重构算法以及得到的以上结论是对多激光导星自适应光学系统实用化有益的探索研究,可将地面层自适应光学模式的视场平均斯特列尔比从0.17提高到0.26,视场中心的的斯特列尔比从0.18提高到0.45。将对我国多激光导星自适应光学系统的发展起到一定的推动作用。
[Abstract]:The adaptive optical system usually divides the light energy of the target to more than 60% for the wavefront detection. In addition, the Hartmann wavefront detector usually used in the adaptive optical system is to reconstruct the telescope before the wavefront of the telescope is divided into a wavelet with a diameter of only 10cm, and to reconstruct the wavefront of the sub beam to reconstruct the wavefront. The telescope received the whole wave front, where the optical energy received by the sub aperture is only equivalent to the 10cm aperture telescope, so the traditional adaptive optical system can correct the limit of imaging only 5 stars! Using the laser guide to detect the wavefront can not only improve the limit stars of the imaging target, but also make the adaptive optical system possible. However, the height of the laser guided star is much lower than that of the image target, which leads to the unequal halo error of the wavefront missing information of the detection. Therefore, it is the key to use multiple guides to make up for the missing wavefront information and the information fusion and reconstruction of the wavefront. Firstly, according to the universally recognized atmospheric refractive index structure model of Hufnagel-Valley, the vertical distribution function of atmospheric refractive index is used as the basis of the layered weight distribution of the optical channel, and the height of the equivalent surface of each layer is calculated by the height order moment algorithm. It is concluded that the channel of atmospheric turbulence affecting the wavefront is from the ground to the 15km height. 99.3% of all atmospheric turbulence can be concentrated, which can be approximately considered from the ground to 8km height, which concentrates 96% of the total atmospheric turbulence, and the 15km atmospheric channel can be divided into three layers of approximately equal density or the 8km atmosphere channel is divided into two layers of approximately equal density: the first layer is from the ground to the 1.65km, the equivalent surface height is 0.15km, and the turbulence intensity weight is weighted. For 88.2%, the second layer from 1.65km to 8.00km, the equivalent surface height is 3.78km, the weight of the turbulence intensity is 7.1%, the third layer from 8.00km to 15km, the equivalent surface height is 11.20km, and the weight of the turbulence intensity is 4.0%. to propose a dynamic phase screen generation method which conforms to the spatial statistical characteristics and the time statistical properties of atmospheric turbulence, and the atmosphere is based on this method. The turbulence simulation program provides a basis for the verification and analysis of the wavefront reconstruction algorithm. The plane weighted wavefront reconstruction method of multiple Rayleigh guide star wavefront signals on the receiving plane of the foundation telescope is proposed. Based on the phase structure function, the wavefront detection signal of the guide star is calculated at the center of the projection position of each guide star on the ground. The weighted fusion function of the radially and azimuth of the telescope receives the weighted fusion function of the telescope and carries out the weighted fusion of multiple star wavefronts to complete the wavefront reconstruction of the imaging target. For the telescope aperture is 1.25m, the atmospheric coherence length is 10cm, 5 zigzag arrangement, the overlap of the circle and the telescope aperture, the height of the Rayleigh guide with a height of 10km, is added to the plane. The weight algorithm simulates the correction of the target imaging on the axis, and does not consider the correction error in the steerr's theory, which can theoretically reach 0.49. to further consider the non sampling error of the atmosphere above the 10km height, and the upper layer error is calculated to be 0.57rad, so the total error RMS of the wavefront detection is increased to 1.02rad, converted to the system's steerratio. It can reach 0.35, indicating that the five 10km height Rayleigh guide can meet the practical requirements. The test optical system on the optical platform is built. The experimental results coincide with the theoretical value. It is proved that the algorithm of plane weighted wavefront reconstruction is accurate enough. For the application of multi-layer conjugate adaptive optical imaging for large aperture telescope over 4 meters, the application of the multi-layer conjugate adaptive optical imaging is necessary. Using a sodium guide star with a height of 90km, a generalized Tikhonov regularized Zernike mode layered analytic reconstruction wave front algorithm is used to avoid the problem of oversize of the projection matrix. When the telescope aperture is 8m, the atmospheric coherence length is 12cm, 3 90km height sodium laser guides are adopted, and the generalized Tikhonov regularization method of Zernike mode is analyzed. The average error of the wavefront reconstruction algorithm in the 1 angle field of view is 0.68rad, and its corresponding stellar ratio is 0.63 and the diffraction limit resolution is 1.26 times. In the multi-layer conjugate adaptive optical system, the number of sodium guide stars is 3-5, the number of corrector is 2-3, and the number of guide stars and the number of corrector are further increased to the adaptive system. The best distribution of the system is that the best distribution of the guide star is as follows: 2 guide stars are linear distribution, the guide star corresponding to the center of view is 15.7 ", the three guide stars are triangle distribution, the guide star corresponding to the center angle of the field of view is 21.5", the four guide star is square, the guide star corresponding to the center of view is 23.5 ", and the five star is the regular pentagon distribution. The center angle of the guide star is 27.4 ". The best conjugate height of the corrector is only related to the vertical distribution of the atmospheric turbulence intensity. When the two corrector is used, the best conjugate height is 0km and 10km. When using three corrector, the best conjugate height is the wavefront reconstruction algorithm and the above conclusion proposed in this paper, 0km, 2km and 11km.. The theory is a useful exploration for the practical application of the multi laser guide star adaptive optical system, which can increase the field of view of the adaptive optical mode of the ground layer from 0.17 to 0.26, and the STL ratio from 0.18 to 0.45. in the center of the field of view will give a certain push to the development of the self adaptive optical system of our country's multi laser guide star. Use.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O439
本文编号：2175138
[Abstract]:The adaptive optical system usually divides the light energy of the target to more than 60% for the wavefront detection. In addition, the Hartmann wavefront detector usually used in the adaptive optical system is to reconstruct the telescope before the wavefront of the telescope is divided into a wavelet with a diameter of only 10cm, and to reconstruct the wavefront of the sub beam to reconstruct the wavefront. The telescope received the whole wave front, where the optical energy received by the sub aperture is only equivalent to the 10cm aperture telescope, so the traditional adaptive optical system can correct the limit of imaging only 5 stars! Using the laser guide to detect the wavefront can not only improve the limit stars of the imaging target, but also make the adaptive optical system possible. However, the height of the laser guided star is much lower than that of the image target, which leads to the unequal halo error of the wavefront missing information of the detection. Therefore, it is the key to use multiple guides to make up for the missing wavefront information and the information fusion and reconstruction of the wavefront. Firstly, according to the universally recognized atmospheric refractive index structure model of Hufnagel-Valley, the vertical distribution function of atmospheric refractive index is used as the basis of the layered weight distribution of the optical channel, and the height of the equivalent surface of each layer is calculated by the height order moment algorithm. It is concluded that the channel of atmospheric turbulence affecting the wavefront is from the ground to the 15km height. 99.3% of all atmospheric turbulence can be concentrated, which can be approximately considered from the ground to 8km height, which concentrates 96% of the total atmospheric turbulence, and the 15km atmospheric channel can be divided into three layers of approximately equal density or the 8km atmosphere channel is divided into two layers of approximately equal density: the first layer is from the ground to the 1.65km, the equivalent surface height is 0.15km, and the turbulence intensity weight is weighted. For 88.2%, the second layer from 1.65km to 8.00km, the equivalent surface height is 3.78km, the weight of the turbulence intensity is 7.1%, the third layer from 8.00km to 15km, the equivalent surface height is 11.20km, and the weight of the turbulence intensity is 4.0%. to propose a dynamic phase screen generation method which conforms to the spatial statistical characteristics and the time statistical properties of atmospheric turbulence, and the atmosphere is based on this method. The turbulence simulation program provides a basis for the verification and analysis of the wavefront reconstruction algorithm. The plane weighted wavefront reconstruction method of multiple Rayleigh guide star wavefront signals on the receiving plane of the foundation telescope is proposed. Based on the phase structure function, the wavefront detection signal of the guide star is calculated at the center of the projection position of each guide star on the ground. The weighted fusion function of the radially and azimuth of the telescope receives the weighted fusion function of the telescope and carries out the weighted fusion of multiple star wavefronts to complete the wavefront reconstruction of the imaging target. For the telescope aperture is 1.25m, the atmospheric coherence length is 10cm, 5 zigzag arrangement, the overlap of the circle and the telescope aperture, the height of the Rayleigh guide with a height of 10km, is added to the plane. The weight algorithm simulates the correction of the target imaging on the axis, and does not consider the correction error in the steerr's theory, which can theoretically reach 0.49. to further consider the non sampling error of the atmosphere above the 10km height, and the upper layer error is calculated to be 0.57rad, so the total error RMS of the wavefront detection is increased to 1.02rad, converted to the system's steerratio. It can reach 0.35, indicating that the five 10km height Rayleigh guide can meet the practical requirements. The test optical system on the optical platform is built. The experimental results coincide with the theoretical value. It is proved that the algorithm of plane weighted wavefront reconstruction is accurate enough. For the application of multi-layer conjugate adaptive optical imaging for large aperture telescope over 4 meters, the application of the multi-layer conjugate adaptive optical imaging is necessary. Using a sodium guide star with a height of 90km, a generalized Tikhonov regularized Zernike mode layered analytic reconstruction wave front algorithm is used to avoid the problem of oversize of the projection matrix. When the telescope aperture is 8m, the atmospheric coherence length is 12cm, 3 90km height sodium laser guides are adopted, and the generalized Tikhonov regularization method of Zernike mode is analyzed. The average error of the wavefront reconstruction algorithm in the 1 angle field of view is 0.68rad, and its corresponding stellar ratio is 0.63 and the diffraction limit resolution is 1.26 times. In the multi-layer conjugate adaptive optical system, the number of sodium guide stars is 3-5, the number of corrector is 2-3, and the number of guide stars and the number of corrector are further increased to the adaptive system. The best distribution of the system is that the best distribution of the guide star is as follows: 2 guide stars are linear distribution, the guide star corresponding to the center of view is 15.7 ", the three guide stars are triangle distribution, the guide star corresponding to the center angle of the field of view is 21.5", the four guide star is square, the guide star corresponding to the center of view is 23.5 ", and the five star is the regular pentagon distribution. The center angle of the guide star is 27.4 ". The best conjugate height of the corrector is only related to the vertical distribution of the atmospheric turbulence intensity. When the two corrector is used, the best conjugate height is 0km and 10km. When using three corrector, the best conjugate height is the wavefront reconstruction algorithm and the above conclusion proposed in this paper, 0km, 2km and 11km.. The theory is a useful exploration for the practical application of the multi laser guide star adaptive optical system, which can increase the field of view of the adaptive optical mode of the ground layer from 0.17 to 0.26, and the STL ratio from 0.18 to 0.45. in the center of the field of view will give a certain push to the development of the self adaptive optical system of our country's multi laser guide star. Use.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O439
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