共查询到19条相似文献,搜索用时 62 毫秒
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建立了一个小型Hartmann-Shack波前传感器来测量大气扰动特征。通过单子孔径的象移和许多间距不同的子孔径之间的象移差测得的到达角起伏的统计值来计算出Fried参数r0。本文推导了采用不同孔径参数的实验结果,以及波前斜率的功率谱密度。 相似文献
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波前传感器是自适应光学系统的重要组成部分。讨论了Hartmann-0Shack-(H-S)波前传感顺的采样频率对探测误差的影响,理论分析结果说明,时域采样频率引入的探测误差H-S波前传感器的重要误差源,其大小随时域采样频率的增大而下降。 相似文献
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提高Hartmann波前传感器质心探测精度的阈值方法 总被引:3,自引:3,他引:3
详细地讨论了Hartmann波前传感器质探测的误差来源。主要讨论了光量子起伏、CCD的背影电子噪声引起的质心探测误差,并对采样阈值对Hartmann波前传感器质心探测精度的影响进行了分析。本文对Hartmann波前传器的经设计以及实际操作提供了一定的理论依据。 相似文献
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精确的测量和控制星载望远镜的波前像差是实现高效空间引力波探测的关键。本文提出了一种基于夏克-哈特曼波前传感器原理的星载望远镜波前像差测量方法,该方法采用经过频域阈值去噪处理后的频域上的互相关算法,使用子孔径数20×16、微透镜尺寸0.279 mm×0.279 mm、焦距34 mm的夏克-哈特曼波前传感器对算法的测量精确度进行验证。对实际点源图像生成已知RMS离焦值(0, 0.22, 0.44, 0.66 nm),从而产生具有偏移量的点源图像。使用模式法进行波前复原后,计算复原波面和残余波面的RMS值,用于比较频域上的互相关算法和传统质心算法的测量精度。结果显示,随着实际离焦值的增加,质心算法的测量误差呈现上升趋势,分别为0.0966 nm, 0.1378 nm,0.1284 nm和0.1463 nm。频域互相关算法可以使夏克-哈特曼波前像差均方根(RMS)误差分别减少13%, 7%, 18%和14%,为空间引力波星载望远镜地面波前像差的高精度测试提供了重要参考。 相似文献
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自适应光学系统中变形镜和波前传感器共轭位置要求的分析 总被引:1,自引:1,他引:0
通过对几何光学和物理光学模型的数值计算,分析了自适应光学系统中小像差畸变波前在空间自由传播时自身的变化情况,进而给出了系统中对变形镜和波前探测器与被校正瞳面之间共轭位置关系的要求和允许范围.结果表明,波前自由传播时的变化程度决定于像差自身的类型和大小、光束的口径以及传播的距离,大口径小像差波前近距离传播时波前变化误差很小.一般来说,变形镜和波前传感器偏离被校正瞳面共轭位置距离满足菲涅尔数大于1000时,对系统校正效果的影响可以忽略.实际应用中,应该根据校正对象的特征来具体计算波前误差随传播距离的变化,从而设计波前传感器和变形镜的位置,以及选择使用4F光学系统.本文的分析可以为自适应光学系统的整体光路设计提供一定理论参考. 相似文献
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A Shack-Hartmann sensor nonintrusive measurement for the temperature profile in a heat-capacity neodymium-doped glass rod is proposed. This technique is possible because the optical path length of the rod changes with temperature linearly over a wide range. The temperature change of the solid-state laser rod is often recorded by using a thermocouple, thermal camera, or phase-shifting interferometer. Based on an analysis of temperature-induced changes in length and index of refraction, we can get the temperature profiles from the wavefront reconstructions in real time. The results suggest the Shack-Hartmann sensors could replace microbolometer-based thermal cameras and phase-shifting interferometers for dynamic temperature profiles in heat-capacity laser rods with particular advantages. A strange temperature chaos of the Nd:glass rod just after the pump cycle is discovered. 相似文献
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We propose to add a specific phase chessboard to the classical Hartmann mask used for wave-front sensing. By doing this we obtain a pseudoguiding of the energy issuing from this mask, allowing for an increase in the sensitivity of the Hartmann test. This property is illustrated by experiment, and a comparison between classical and new Hartmanngrams is presented. 相似文献
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Strongly aberrated wavefronts lead to inaccuracies and nonlinearities in holography-based modal wavefront sensing (HMWS). In this contribution, a low-resolution Shack-Hartmann sensor (LRSHS) is incorporated into HMWS via a compact holographic design to extend the dynamic range of HMWS. A static binary-phase computer-generated hologram is employed to generate the desired patterns for Shack-Hartmann sensing and HMWS. The low-order aberration modes dominating the wavefront error are first sensed with the LRSHS and corrected by the wavefront modulator. The system then switches to HMWS to obtain better sensor sensitivity and accuracy. Simulated as well as experimental results are shown for validating the proposed method. 相似文献
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The action of an acoustic field on a nonisothermal gaseous medium for the purpose of improving the optical characteristics of the medium is studied. Restoration of optical uniformity of the gas and stabilization of the wavefront of a laser beam were modelled in experiments with acoustic flows.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 2, pp. 235–238, February, 1990. 相似文献
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A modal wavefront sensor for ocular aberrations exhibits two main advantages compared to a conventional Shack–Hartmann sensor. As the wavefront is detected in the Fourier plane, the method is robust against local loss of information (e.g. local opacity of ocular lens as in the case of cataract), and is not dependent on the spatial distribution of wavefront sampling. We have proposed a novel method of wavefront sensing for ocular aberrations that directly detects the strengths of Zernike aberrations. A multiplexed Fourier computer-generated hologram has been designed as the binary phase element (BPE) for the detection of second-order and higher-order ocular aberrations (HOAs). The BPE design has been validated by comparing the simulated far-field pattern with the experimental results obtained by displaying it on a spatial light modulator. Simulation results have demonstrated the simultaneous wavefront detection with an accuracy better that ~λ/30 for a measurement range of ±2.1λ with reduced cross-talk. Sensor performance is validated by performing a numerical experiment using the City data set for test waves containing second-order and HOAs and measurement errors of 0.065?µm peak-to-valley (PV) and 0.08?µm (PV) have been obtained, respectively. 相似文献
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运用衍射理论计算出两个离焦面上的光强分布,从而获得波前曲率和孔径边缘的波前径向倾斜。根据Zernike多项式的微分特性,采用两种不同的方法分别处理曲率和倾斜,使用积分的方法解决了在边界上δ函数很难处理的问题。由探测器的几何分布预先算出控制矩阵,用Zernike多项式曲线拟合的方法重构出波前。计算机仿真表明,波前残差小于5%,验证了此波前重构算法的可行性。 相似文献
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An analytic expression for the distribution density of a random variable at the output of a quadrant photodetector that performs
sum-difference processing a, Poisson signal is obtained. The precision characteristics of a Hartmann sensor in the presence
of Poisson and Gaussian noise are analyzed on the basis of the expression. Expressions for the mathematical expectation and
variance of the noise-induced error variance and the correlation coefficents, of the results of reconstruction of the phase
front are obtained.
Translated from Izmeritel'naya Tekhnika, No. 9, pp. 38–42, September, 1999. 相似文献
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Herzog WD Tysk SM Tardiff DW Cappiello GG Jong JM Jeys TH Hoffeld RH Sanchez A Daneu V 《Applied optics》2007,46(16):3150-3155
What is believed to be a new concept for the measurement of micrometer-sized particle trajectories in an inlet air stream is introduced. The technique uses a light source and a mask to generate a spatial pattern of light within a volume in space. Particles traverse the illumination volume and elastically scatter light to a photodetector where the signal is recorded in time. The detected scattering waveform is decoded to find the particle trajectory. A design is presented for the structured laser beam, and the accuracy of the technique in determining particle position is demonstrated. It is also demonstrated that the structured laser beam can be used to measure and then correct for the spatially dependent instrument-response function of an optical-scattering-based particle-sizing system for aerosols. 相似文献