H—S波前传感器时域采样频率对探测误差的影响

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。     

波前传感器子孔径数和信标亮度的匹配

针对云南天文台１．２ｍ望远镜上的６１单元高分辨率自自应光学系统，进行了微光工作环境下波前传感器子孔径数和信标亮度匹配的实验研究。在Ｈａｒｔｍａｎｎ－Ｓｈａｃｋ波前传感器前的平行光路加入一个变倍光学系统，进行了８＊８、６＊６、４＊４和２＊２子孔径阵列在不同信标亮下波前感器对波前的探测实验。     

用Hartmann—Shack波前传感器测量大气湍流特征

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。     

用Hartmann—Shack传感器测量激光束的波前相位

Ｈａｒｔｍａｎｎ－Ｓｈａｃｋ传感器已经用于自适应光学系统。它可以同时探测出一束光的振幅和相位信息。通过一个位置传感器，比如ＣＣＤ，它就可以成为一种对光学系统和光束的静态和动态质量诊断的有力工具。从Ｈ－Ｓ波前传感器的输出（波前斜率和近场强度分布），就可以推算出远场特点，如ＰＳＦ和ＯＦＴ。本文将介绍波前重构的理论分析和远场特征评估。同时也给出了光束质量的静态和动态的测量结果。     

动态波前相位的高分辨率测量

动态波前相位信息测量是大气光学，气动光学和激光技术等领域的重要实验手段。提出了一种具有高的时间和空间分辨率以及长的测量持续时间的动态波前相位测量方法。应用Ｈａｒｔｍａｎｎ－Ｓｈａｃｋ波前传感器获得高空间分辨率的相位信息，采用高帧频ＣＣＤ摄象机获得高时间分辨率图象数据。     

用Hartmann－Shack传感器测量激光束的波前相位

Ｈａｒｔｍａｎｎ－Ｓｈａｃｋ传感器已经用于自适应光学系统。它可以同时探测出一束光的振幅和相位信息。通过一个位置传感器，比如ＣＣＤ，它就可以成为一种对光学系统和光束的静态和动态质量诊断的有力工具。从Ｈ－Ｓ波前传感器的输出（波前斜率和近场强度分布），就可以推算出远场特点，如ＰＳＦ和ＯＴＦ。本文将介绍波前重构的理论分析和远场特征评估。同时也给出了光束质量的静态和动态的测量结果。     

用Hartmann－Shack波前传感器测量大气湍流特征

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。     

测量高功率激光束衍射光斑阵列位置的图象处理方法

介绍了测量高功率激光束射光斑阵列的各光斑中心位置的计算机图象处理方法。讨论了ＴＩＦＦ图象格式的全用技巧，利用灰度级确定各衍射光斑光强中心以及去除噪声光点的计算机处理方法，用计算机软件实现了常规Ｈａｒｔｍａｎｎ－Ｓｈａｃｋ传感器中子透镜阵列的子光束聚焦过程。     

H—S法波前探测的高速图象采集系统

自适应光学系统中有两种方法用于测定波前的局部斜率：剪切干涉测量法和哈特曼法（以下简称Ｈ－Ｓ法）。由于Ｈ－Ｓ法运用较简单的光学系统，无需任何活动组件，具有较高的光效率，并能很好地用于探测器阵列，因此它更普遍地用于自适应光学系统中。本文介绍了一种应用于Ｈ－Ｓ法波前探测的高速图象采集系统，提出了应用本图象采集系统解决高帧频探测器阵列与数据处理机之间的同步协调的方法。     

H－S法波前探测的高速图象采集系统

自适应光学系统中有两种方法用于测定波前的局部斜率：剪切干涉测量法和哈特曼法（以下简称Ｈ－Ｓ法）。由于Ｈ－Ｓ法运用较简单的光学系统，无需任何活动组件，具有较高的光效率，并能很好地用于探测器阵列，因此它更普遍地用于自适应光学系统中。本文介绍了一种应用于Ｈ－Ｓ法波前探测的高速图象采集系统，提出了应用本图象采集系统解决高帧频探测器阵列与数据处理机之间的同步协调的方法。     

Novel methods to improve the measurement accuracy and the dynamic range of Shack–Hartmann wavefront sensor

As a wavefront sensor, the Shack–Hartmann wavefront sensor plays an important role in the wavefront measurement of human eyes. However, the low measurement accuracy and the small dynamic range of Shack–Hartmann wavefront sensor limit its application. In this paper, we present a matched-filter algorithm to improve the measurement accuracy by more than an order of magnitude. Moreover, we also introduce a new algorithm to extend the dynamic range of Shack–Hartmann wavefront sensor. With this method, the recorded spots of Shack–Hartmann wavefront sensor are not constrained to stay in the corresponding pixel area of the microlens. The result shows that the dynamic range can be extended from 57.1 to 160% for the first 24 items of Zernike wavefronts, respectively. The improvement by our methods makes the Shack–Hartmann more suitable for the measurement of highly aberrated eyes.     

Shack Hartmann wave-front measurement with a large F-number plastic microlens array

A new plastic microlens array, consisting of 900 lenslets, has been developed for the Shack Hartmann wave-front sensor.The individual lens is 300 μm × 300μm and has a focal length of 10 mm, which provides the same focal size, 60 μm in diameter, with a constant peak intensity. One can improve thewave-front measurement accuracy by reducing the spot centroiding error by averaging a few frame memories of an image processor. A deformable mirror for testing the wave-front sensor gives anappropriate defocus and astigmatism, and the laser wave front is measured with a Shack Hartmann wave-front sensor. The measurement accuracy and reproducibility of our wave-front sensor are better than λ/20 and λ/50 (λ = 632.8 nm),respectively, in rms.     

Sampling error analysis of Shack–Hartmann wavefront sensor with variable subaperture pixels

Abstract

The sampling error of a Shack–Hartmann wavefront sensor with variable subaperture pixels is analysed under the consideration of various threshold values and detecting dynamic ranges. A generalized expression, which is used for fitting the sampling error of a Shack-Hartmann wavefront sensor with variable subaperture pixels, is presented. The computational results of the sampling error of a Shack–Hartmann wavefront sensor with different pixel numbers per subaperture, different detecting dynamic ranges, different atmospheric coherence length, different extended degree of the object and the different threshold values are also given. The results indicate that the sampling error of the Shack–Hartmann wavefront sensor is sensitive to the dynamic range of the subaperture, the pixel numbers per subaperture, the extended degree of the object and the coherent length of atmosphere, but not sensitive to the threshold value.     

衍射微透镜列阵质量评价方法研究

根据实际工程需要 ,对用于萨克 -哈特曼波前传感器的二元衍射微透镜列阵衍射效率的评价方法进行了研究。导出了制作误差与衍射效率的关系式 ,研究了由测得的制作误差评估衍射效率的方法 ,并建立了一套测量系统。     

An ocular wavefront sensor based on binary phase element: design and analysis

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.     

Adaptive Control of a Micromachined Continuous Membrane Deformable Mirror for Aberration Compensation

ＩｎｔｒｏｄｕｃｔｉｏｎＡｃｔｉｖｅｍｉｒｏｒｓａｒｅｉｎｄｉｓｐｅｎｓａｂｌｅｅｌｅｍｅｎｔｓｆｏｒａｄａｐｔｉｖｅｏｐｔｉｃｓ［１］．Ｒｅｃｅｎｔａｄｖａｎｃｅｓｏｆｔｈｅｍｉｃｒｏｍａｃｈｉｎｅｄｍｅｍｂｒａｎｅｄｅｆｏｒｍａｂｌｅｍｉｒｏｒ（...     

Plenoptic camera wavefront sensing with extended sources

Abstract

The wavefront sensor is used in adaptive optics to detect the atmospheric distortion, which feeds back to the deformable mirror to compensate for this distortion. Different from the Shack–Hartmann sensor that has been widely used with point sources, the plenoptic camera wavefront sensor has been proposed as an alternative wavefront sensor adequate for extended objects in recent years. In this paper, the plenoptic camera wavefront sensing with extended sources is discussed systematically. Simulations are performed to investigate the wavefront measurement error and the closed-loop performance of the plenoptic sensor. The results show that there are an optimal lenslet size and an optimal number of pixels to make the best performance. The RMS of the resulting corrected wavefront in closed-loop adaptive optics system is less than 108 nm (0.2λ) when D/r₀ ≤ 10 and the magnitude M ≤ 5. Our investigation indicates that the plenoptic sensor is efficient to operate on extended sources in the closed-loop adaptive optics system.     

Experiments of two pupil lateral motion tracking algorithms using a Shack–Hartmann sensor

Pupil stability is one of the factors which limit the performance and operational stability of adaptive optics (AO) systems. This paper analyses two pupil-tracking methods to measure the lateral pupil shift: the first one utilizes the fluxes in all outer edge sub-apertures of a Shack–Hartmann sensor and the second one utilizes the real-time interaction matrix used in an AO system. Experiments with 9?×?9 Shack–Hartmann sensor are conducted to verify both pupil-tracking algorithms. The results show that both algorithms are effective, after two correction steps, the residual pupil shift is reduced to less than 5% of a Shack–Hartmann sub-aperture.