子孔径拼接干涉检测大口径平面波前

介绍了子孔径拼接检测平面波前的基本原理,提出了基于均化误差和最小二乘法的多个子孔径同时拼接的数据处理方法,有效减小了误差传递和积累.用该方法对Zemax仿真的望远镜光学系统进行了子孔径拼接检测,拼接光学系统波前和直接用Zemax得到的全孔径波前对比,其峰谷值(PV)和均方根(RMS)的偏差分别为0.015 1λ和0.0016λ.并用口径为100 mm的小口径干涉仪对口径为200 mm的平面镜进行了拼接实验,将其全孔径波前与直接检测的结果对比,其峰谷值(PV)和均方根(RMS)的偏差分别为0.055 9λ和0.0004λ.实验结果表明了该算法的有效性,该方法不仅适用于检测光学元件,也适用于对光学系统平面波前检测.     

基于电光马赫-曾德尔干涉仪的飞秒光梳载波包络相移快速调节技术

介绍了一种基于电光晶体马赫-曾德尔干涉仪的载波包络相移快速调节方法,对此方法进行了理论分析和仿真计算,并搭建了一套基于电光晶体马赫-曾德尔干涉仪的载波包络相移调节的光梳实验系统。与超稳激光进行拍频以验证其调节效果,证明可实现8 MHz的载波包络相移调节范围,为窄光梳的实现提供了一种技术手段。     

光盘基片平整度的相移干涉测量方法

使用工作波长为10.6mm的红外激光平面干涉仪对光盘基片的表面面形进行了移相式干涉法测试,对测试的波面数据进行多项式拟合,并用计算机处理测试结果,实现了光盘平整度的自动化测量。所测光盘基片平整度的峰谷值为7.88mm,均方根值为2.0mm。     

光楔分光中波红外Fizeau型干涉仪光学系统设计

针对中波红外波段胶合立方型分束镜分光局限的问题，本文提出基于光楔分光的中波红外Fizeau干涉仪光学设计方案。在3.39μm工作波长下，为降低干涉系统回程误差，提升测量准确度，采用了两次反射折叠准直光路结构，既保证良好的准直波前，同时优化设计光楔兼顾干涉成像波前。设计采用ZnSe、CaF₂材料，干涉仪准直镜为单片平凸非球面结构，成像镜由双分离式球面镜构成，经蒙特卡罗模拟公差分析，准直镜0.1°视场内准直波前PV优于λ/4，归一化出射孔径内角像差优于3.01×10^-5 rad；干涉成像光路归一化视场成像波前PV优于λ/5，在25 lp/mm处MTF值优于0.38，干涉系统最大成像畸变优于0.11%；在标准面0°视场放置，被测表面倾斜0.05°内干涉系统回程误差小于λ/50。基于光楔分光的中波红外Fizeau干涉仪为中波红外干涉仪光学系统设计提供了新的思路。     

基于数字波面干涉的平面度测试方法

本文介绍了一种基于数字波面干涉的平面度测试方法,该方法基于菲索干涉仪结构,通过数字CCD采集单帧干涉图像,运用zernike函数基于单帧图像拟合被测平面三维面型,以PV值综合评价整体平面度,区别于传统的等厚干涉仪与移相干涉测试方法。经验证此方法正确可行,测试数据准确可靠。     

193nm移相点衍射干涉仪的测量误差分析

为了提高移相点衍射干涉仪对193 nm投影光刻系统的检测精度,本文对其主要测量误差进行了探讨.在简要介绍了193 nm移相点衍射干涉仪的基本结构和测量原理之后,总结了可能对测量结果产生影响的各种误差及其产生的原因.通过理论分析和数值模拟的方法分别对参考波前误差,相移误差、探测器非线性误差以及光源波动,环境变化引起的随机误差等进行了具体分析,从而得到各种测量误差的大小、存在形式以及与干涉仪结构参数的依赖关系,并提出了相应的避免或减小误差的方法.     

基于标记点的子孔径全局优化拼接检测法

为实现小口径干涉仪完成较大口径光学平面镜片的测试,得到镜片的完整面形信息,提出了基于标记点的平面Givens变换,实现了子孔径的精确定位.采用Zemike多项式拟合对每个子孔径数据进行了消倾斜量的处理.建立了全局优化拼接数学模型.利用该模型进行了九孔径拼接计算机仿真实验,利用该方法得到的PV值和RMS值的相对误差均在10-6左右.对直径为150 mm的镜片进行九孔径拼接检测实验,对比全口径干涉检测结果,PV值和RMS值的相对误差为0.36%和2.27%.仿真和实验结果证明:该方法稳定可靠,降低了传统的子孔径拼接干涉检测方法中对导轨的高精度要求.     

单频激光干涉仪条纹的偏振移相细分技术

提出了一种用于单频激光干涉仪条纹细分的偏振移相技术.通过偏振分光镜、波片等光学元器件产生四路依次相差90°相位的激光干涉信号,经过硬件电路的整形、放大和比较后,可以解决常见的光强"零漂"问题.共光路设计有效地消除了由于环境因素给测量带来的误差,提高了干涉系统的稳定性和重复性.移相技术不仅充分地利用光能量,而且四路信号更便于干涉条纹的计数和判向,同时为电子细分技术奠定了基础.     

一种新型单频激光干涉系统的研究

这种单频激光干涉系统采用共光路设计布局,通过偏振分束器以及1/4波长片等光学器件对干涉条纹进行空间移相,提取相位依次相差90°的三路干涉输出信号,进行比较放大,解决了常规单频激光干涉仪中的光强“零漂”问题。利用共模抑制技术,提高了干涉系统的测量稳定性和重复性。采用光程差放大技术,提高了干涉系统的分辨力。     

Φ300非球面激光平行光管的研制

此激光平行光管具有以前平行光管的优点,且可以与数字相移干涉仪对接,直接进行波前误差的高精度测量.分别用于三种波长,主波长λ=0.6328μm,另有λ=0.532μm和λ=1.06μm两种波长.基于三级像差理论,得出了采用非球面单透镜的平行光管的光学设计初始参数.以通光口径为Φ300mm、后截距为4616mm物镜为例,分析了不同波长下的波差、球差和有效焦距的变化情况.在其设计、加工、检验和装调上解决了诸多关键技术研制出了此规格的平行光管.最终物镜的波前误差达到0.11λ(λ=0.6328μm).     

Shack-Hartmann wavefront sensor measurement for dynamic temperature profiles in heat-capacity laser rods

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.     

High-resolution retinal imaging with micro adaptive optics system

Based on the dynamic characteristics of human eye aberration, a microadaptive optics retina imaging system set is established for real-time wavefront measurement and correction. This paper analyzes the working principles of a 127-unit Hartmann-Shack wavefront sensor and a 37-channel micromachine membrane deformable mirror adopted in the system. The proposed system achieves wavefront reconstruction through the adaptive centroid detection method and the mode reconstruction algorithm of Zernike polynomials, so that human eye aberration can be measured accurately. Meanwhile, according to the adaptive optics aberration correction control model, a closed-loop iterative aberration correction algorithm based on Smith control is presented to realize efficient and real-time correction of human eye aberration with different characteristics, and characteristics of the time domain of the system are also optimized. According to the experiment results tested on a USAF 1951 standard resolution target and a living human retina (subject ZHY), the resolution of the system can reach 3.6?LP/mm, and the human eye wavefront aberration of 0.728λ (λ=785?nm) can be corrected to 0.081λ in root mean square (RMS) so as to achieve the diffraction limit (Strehl ratio is 0.866), then high-resolution retina images are obtained.     

恒星干涉仪延迟线系统地面随机振动响应分析

研究地面随机微振动对恒星干涉仪关键部件-光学延迟线系统性能的影响。利用美国蓝氏(Lansmont)集团生产的SAVER 3X型三轴振动仪实测地面随机振动信号,以输出的G加速度功率谱密度为激励,运用Workbench有限元分析软件计算该结构系统的随机振动响应;根据抛物镜面节点数据拟合出抛物镜面的Zernike多项式系数、抛物镜刚体平移量和抛物镜面PV和RMS值;将Zernike多项式系数导入光学系统中分析光学延迟线系统光学性能;最后利用ELCOWAT 3000电子自准直仪测量抛物镜刚体平移量,分析实际测量结果和计算理论结果偏差。分析计算结果与实验数据最大偏差7.6%,计算抛物镜面形RMS值为9.6 nm,PV值为46.1 nm,波前差为0.043λ。目前的光学延迟线的地面振动满足光学延迟线系统的稳定性要求。使用动态光学性能标准分析判断微振动对系统光学性能的影响程度,为恒星干涉仪其他子系统优化设计和隔振补偿措施提供参考。     

Misalignment aberrations calibration in testing of high-numerical-aperture spherical surfaces

The calibration of misalignment aberrations is a key issue in the testing of high-numerical-aperture spherical surfaces, and it is hard to separate the high-order aberrations introduced by misalignment from the measured data. The traditional calibration method is still applicable in the case of only wavefront tilt, but no longer effective in the existence of defocus. A calibration technique based on the wavefront difference is proposed to calibrate the misalignment aberrations in the presence of wavefront defocus, and it can be carried out without foreknowledge of the spherical surface under test. With the wavefront difference method, the calibration needs two separate measurements to separate the high-order aberrations. Both the computer simulation and experiments with the ZYGO interferometer have been carried out to validate the proposed calibration technique, with the accuracies better than 0.0005λ RMS and 0.0010λ RMS achieved, respectively. The proposed calibration method provides a feasible way to lower the requirement on the adjustment in the measurement, while retaining good accuracy.     

Reflective liquid crystal wavefront corrector used with tilt incidence

To allow angular separation of the beam reflected off a liquid crystal wavefront corrector from the incident beam, it is convenient to introduce a small incident angle. This avoids using a beam splitter and the associated energy losses. The effect of the tilt incidence on the liquid crystal wavefront corrector was investigated in this paper. For a parallel aligned liquid crystal wavefront corrector, a simplified model was established and used to analyze the change of the phase modulation under the tilt incidence. The simulated results showed that the effect of the tilt incidence on the phase modulation can be ignored when the angle of tilt incidence is less than 6 degrees. The phase modulation related to the incident angle was measured and the changing trend was similar to the calculated results. The effect of the tilt incidence on the diffraction efficiency of the liquid crystal wavefront corrector was also discussed. The simulated results indicated that the reduction of the diffraction efficiency is less than 1% for incidence angles under 3 degrees. Last, a closed loop correction experiment was done with an incident angle of 1 degrees. After correction, the averaged peak to valley (PV) and root mean square (RMS) of the wavefront were down to 0.15 lambda and 0.03 lambda, respectively, and a resolvable image was acquired.     

Instrumentation in Astronomy III

Two-wavelength holography and phase-shifting interferometry are combined to measure the phase contours of deep wavefronts and surfaces, such as those produced by aspherics, with a variable sensitivity. When interference fringes are very closely spaced, the phase data contain high frequencies where 2 ~ ambiguities cannot be resolved. In this technique, the surface is tested at a synthesized longer equivalent wavelength. The phase of the wavefront is calculated modulo 2φ using phase-shifting techniques at each of two visible wavelengths. The difference between these two phase sets is the phase of the wavefront as it would be measured at λ_eq=λ₁λ₂/|λ₁ ? λ₂ |, assuming that 2π ambiguities can be removed at λ_eq. This technique enables surfaces to be contoured to an accuracy of λ_eq/100.     

Adaptive-optics system with liquid-crystal phase-shift interferometer

We develop an adaptive-optics system based on a Mach-Zehnder radial shearing interferometer with liquid-crystal-device (LCD) phase-shift interferometry (PSI). Using accurate phase calibration and transient nematic driving of the LCD, the developed three-step PSI procedure can be achieved in a time of 5 ms. The proposed Mach-Zehnder radial shearing PSI method reconstructs the phase information using a digital signal processor (DSP). The DSP then computes appropriate control signals to drive a deformable mirror in such a way as to eliminate the wavefront distortion. The current adaptive-optics system is capable of suppressing low-frequency thermal disturbances with a signal-to-noise ratio improvement of more than 20 dB and a steady-state phase error of less than 0.02pi root mean square when the control loop is operated at a frequency of 30 Hz.     

Fabrication and characterization of a third-order nonlinear organic-polymer composite glass waveguide: a self-phase modulator

Composite organic-polymer glass optical waveguides in which coupling to the nonlinear organic-polymer layers was achieved by excitement of the underlying ion-exchanged glass waveguide and coupling of the light to the organic-polymer layer were fabricated and measured. A picosecond pulsed color center laser (λ = 1.5 μm) was used to measure the third-order optical susceptibility χ((3))(-w; w, -w, w) in an organic-dye-polymer composite glass waveguide with a Mach-Zehnder interferometer. For a squaryliumdye-doped poly(methyl methacrylate)-styrene-acrylonitrile matrix polymer layer, a composite χ((3)) of roughly 90, in units of (χLiNbO)(3)((3)), was measured.     

光子计数式动态交变剪切干涉仪噪声分析

在自适应光学系统中，波前探测器的噪声是一个主要误差源，本文中分析了光子计数式动态交变剪切干涉仪波前探测器的噪声情况，从理论上推导了剪切干涉仪相位角均方根误差随光强和采样周期的变化以及变化关系，并首次引入等效噪声带宽对施加滤波后噪改善进行了分析。