基于MEMS技术的自适应光学系统的研究

用自适应光学系统来校正由大气湍流等产生的波前畸变,能够得到很好的效果.通过对自适应光学系统的工作原理进行研究,提出了一种基于MEMS技术的微小型自适应光学系统校正波前畸变的方法,将MEMS技术应用于变形反射镜,并构建了具体的实验平台,用来校正一种人为产生的波前畸变,且阐述了具体的实验过程.实验结果表明,基于MEMS技术的自适应光学系统能够很好地闭环校正波前畸变,且其体积小、质量轻、校正性能稳定,为自适应光学技术在星载相机上的应用提供了依据.     

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

ＩｎｔｒｏｄｕｃｔｉｏｎＡｃｔｉｖｅｍｉｒｏｒｓａｒｅｉｎｄｉｓｐｅｎｓａｂｌｅｅｌｅｍｅｎｔｓｆｏｒａｄａｐｔｉｖｅｏｐｔｉｃｓ［１］．Ｒｅｃｅｎｔａｄｖａｎｃｅｓｏｆｔｈｅｍｉｃｒｏｍａｃｈｉｎｅｄｍｅｍｂｒａｎｅｄｅｆｏｒｍａｂｌｅｍｉｒｏｒ（...     

Machining and metrology systems for free-form laser printer mirrors

A major challenge in optics is to make optical components like mirrors and lenses smaller and cheaper. This is achieved by designing optical components that have conformal or free-form shapes. A free-form optic is defined as one that is not symmetrical about any axis. These highly demanding requirements are met by single point diamond machining in rigid ultra precision machine tools.     

Variable Magnification With Kirkpatrick-Baez Optics for Synchrotron X-Ray Microscopy

We describe the distinction between the operation of a short focal length x-ray microscope forming a real image with a laboratory source (convergent illumination) and with a highly collimated intense beam from a synchrotron light source (Köhler illumination). We demonstrate the distinction with a Kirkpatrick-Baez microscope consisting of short focal length multilayer mirrors operating at an energy of 8 keV. In addition to realizing improvements in the resolution of the optics, the synchrotron radiation microscope is not limited to the usual single magnification at a fixed image plane. Higher magnification images are produced by projection in the limit of geometrical optics with a collimated beam. However, in distinction to the common method of placing the sample behind the optical source of a diverging beam, we describe the situation in which the sample is located in the collimated beam before the optical element. The ultimate limits of this magnification result from diffraction by the specimen and are determined by the sample position relative to the focal point of the optic. We present criteria by which the diffraction is minimized.     

Comparative analysis of Zernike aberrations generation with deformable mirrors for ocular adaptive optics

The micromachined membrane deformable mirror (MMDM) and piezoelectric deformable mirror (PDM) are two types of cost-effective deformable mirrors (DMs) that are widely used in ocular adaptive optics. In the current study, a 59ch MMDM and a 37ch PDM are tested and compared in generation of Zernike aberrations which are the most dominant of the human eye. The results reveal that although PDM performs better in larger scope, both DMs have almost similar performance if the individual generation coefficient is within the range of ±1 µm.     

应力抛光技术加工抛物面的实验研究

大口径非球面加工技术一直是先进光学制造领域研究的前沿课题,本文开展了以大型非球面应力抛光技术(SMP)为核心的相关先进光学制造技术的研究.研究了应力抛光技术的原理及算法,以加工一块口径为φ314mm,F/7的抛物面镜为例,验证应力抛光技术的合理性和有效性.采用干涉仪检测抛光结束的抛物面其峰值(PV)为3.317λ,均方根(rms)为0.489λ.结果表明,应力抛光技术能够以较高精度、快速地形成旋转对称的抛物面,其面形误差满足或接近于非球面面形的精度要求.     

成像光学工程面临的光学问题

文章简单论述了现代成像光学主要领域的情况,指出非球面反射系统是发展的必然趋势。讨论了加工与检验方面的基本情况及应着重深入研究的问题。对镜坯材料也提了一点看法。     

Optics: a bibliometric approach to detect emerging research domains and intellectual bases

Optics is an important research domain both for its scientific interest and industrial applications. In this paper, we constructed a citation network of papers and performed topological clustering method to investigate the structure of research and to detect emerging research domains in optics. We found that optics consists of main five subclusters, optical communication, quantum optics, optical data processing, optical analysis and lasers. Then, we further investigated the detailed subcluster structures in it. By doing so, we detected some emerging research domains such as nonlinearity in photonic crystal fiber, broad band parametric amplifier, and in-vivo imaging techniques. We also discuss the distinction between research front and intellectual base in optics.     

Fabrication of micro optics on coreless fiber segments

Fabrication of micro optics for fiber optics applications is a challenge due to their size and the issues associated with alignment of the optics to single-mode fibers. This study summarizes a method for fabricating diffractive optical elements on the ends of coreless fiber segments for passive alignment to single-mode fibers. Results are presented for passively aligned diffractive lens elements used for both collimation and beam shaping.     

TMC系统主镜的平板补偿自准检验方法

针对TMC(三镜卡塞格林)光学系统凹椭球面主镜的检验,本文提出了一种平板补偿的自准检验方法.该方法克服了OFFENER零位补偿器本身性能难以检验,只能靠加工和装调保证精度的问题.针对TMC主镜面形与抛物面接近的特点,对平板补偿的自准检验方案进行了理论分析,利用二次非球面的法线像差性质推导了检验光路中球差的表达式,并利用最小剩余球差进行补偿平板参数的确定.对某TMC系统顶点曲率1 589mm,二次系数-0.983,口径φ500 mm的主镜检验,设计了尺寸仅为φ34.2 min×9.126 5 mm的补偿平板.在ZEMAX中计算的结果表明,经平板补偿后的检验光路波像差RMS值为0.003λ,可满足TMC主镜的高精度检验要求.对补偿平板的检验方法,以及加工和使用中应当采取的措施也进行了考虑.与常用检验方法相比,本文方法具有容易对平板性能进行检验,成本低、研制周期短等优点.     

自由曲面光学器件检测技术

自由曲面光学器件尽管有其突出的优点,但还远不能进入到现代光学系统的主流中去,问题之一就是精密检测．自由曲面光学器件的检测对于其精密加工不可或缺,并且两者通常具有不可分割的联系．文中阐述了与不同加工阶段相关的自由曲面光学器件检测中的问题和对策．在抛光前后宜分别采用坐标测量机和光学干涉仪,两种方法都存在一些问题有待解决．实际上坐标测量方法是近十几年来自由曲面测量的主流,这方面的研究主要集中于定位、误差补偿及采样策略等问题上．相比之下,自由曲面光学器件的光学测试是一个新的技术,其中不仅是分析软件上的存在问题,首要的还是缺乏适当的测量手段．尽管也可应用专门的轮廓测量仪,但它还存在诸多限制．结合子孔径拼接技术的干涉仪在某些自由曲面光学器件的测量中前景良好,不过对于更复杂的曲面,它同样无法进行测量．     

Theory and laboratory demonstrations on the use of a nematic liquid-crystal phase modulator for controlled turbulence generation and adaptive optics

We discuss the use of liquid-crystal phase modulators (LCPM's) both as a repeatable disturbance test source and as an adaptive optics corrector. LCPM's have the potential to induce controlled, repeatable, dynamic aberrations into optical systems at low cost, low complexity, and high flexibility. Because they are programmable and can be operated as transmissive elements, they can easily be inserted into the optical path of an adaptive optics system and used to generate a disturbance test source. When used as wave-front correctors they act as a piston-only segmented mirror and have a number of advantages. These include low operating power requirements, relatively low cost, and compact size. Laboratory experiments with a Meadowlark LCPM are presented. We first describe use of the LCPM as a repeatable disturbance generator for testing adaptive optics systems. We then describe a closed-loop adaptive optics system using the LCPM as the wave-front corrector. The adaptive optics system includes a Shack-Hartmann wave-front sensor operated with a zonal control algorithm.     

BICGSTAB算法在波前重构和控制中的应用

自适应光学波前重构和控制对精度和实时性的要求很高。BICGSTAB算法可用于非正定对称的线性系统方程的求解,并且速度快、精度高,稳定性好。基于Fried网格,提出将BICGSTAB算法引入自适应光学波前重构和控制系统方程的求解,并与SVD以及几种常见的迭代算法(Jacobi,Seidel,SOR以及SSOR)作比较。仿真结果表明,对于121阶系统,BICGSTAB法达到0.01%精度仅仅需要不到70次的迭代;SVD法达到0.01%需要近300次;四种常见迭代方法即使104次也没有收敛。这说明BICGSTAB具有更高的速度和精度,能够更好地满足自适应光学系统实时性和精度的需要。     

Electric Field Sensing Scheme Based on Matched $ hbox{LiNbO}_{3}$ Electro-Optic Retarders

In this paper, a wideband-electric-field-sensing scheme that uses optically matched integrated optics electrooptic devices and coherence modulation of light is described. In a coherence modulation scheme, the integrated optics sensor detects the electric field and imprints it around an optical delay. The optical delay is generated by a birefringent optical waveguide in a lithium niobate (LiNbO₃) integrated optics two-wave interferometer. The modulated optical delay, acting as an information carrier, is transmitted through an optical fiber channel. At the receiver, light is demodulated by a second integrated optics two-wave interferometer, which also introduces a second optical delay. The optical delays on the sensor and demodulator are matched at the same value. The integrated optics demodulator measures the autocorrelation of light around the optical delay value, and the imprinted electric field is recuperated as a linear variation of the received optical power. The matching of the sensor and demodulator allows a direct detection of the electric field, giving a unique feature to this fiber-integrated optics scheme. The experimental setup described here uses two pigtailed LiNbO₃ electrooptic crystals: one acting as the electric field sensor and the other acting as the optical demodulator. The wideband sensing range on the experimental setup corresponds to frequencies between 0 and 20 kHz.     

自适应光学在空间光学遥感器上的应用

阐述了在空间光学遥感器上应用自适应光学技术的必要性,介绍了国外的ＳＴ－ＭＴ,ＬＤＲ和Ｈｕｂｂｌｅ等几种空间光学遥感器应用自适应光学技术的情况,论述了轻小型和集成化的星载自适应光学系统的技术现状和发展趋势。进行了星载相机主镜温度变形的自适应光学校正实验,改善系数大于１０。这说明,对大口径、高分辨率空间相机采用自适应光学技术校正主镜由于温度场变化而产生的变莆,可以有效地改善波前质量。     

Diffractive optics applied to free-space optical interconnects

The optimum design of free-space optical interconnection systems utilizing diffractive optics is determined from a practical engineering standpoint for systems ranging from space invariant to fully space variant. System volume is calculated in terms of parameters such as the f-number of the diffractive lens, the wavelength of light, and also the total number, size, and separation of the optical sources and detectors. Performance issues such as interconnection complexity, diffraction efficiency, and signal-tonoise ratio are discussed. Diffractive optics fabricated by electron-beam direct-write techniques are used to provide experimental results for both shuffle-exchange and twin-butterfly free-space optical interconnects.     

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。     

The influence of high-frequency phase and correction distance on the phase correction effect

By studying the propagation characteristics of the wavefront phase of laser beams in adaptive optics systems, the influence of the high-frequency phase on the correction effect has been analyzed and the variations of correction effect with the position of optical deformable mirror have been analyzed quantitatively. The results show that the beam quality of the corrected beam in far field obviously degrades with an increase of high-frequency phase in a distorted wavefront, and the correction effect becomes worse and worse. In addition, the correction effect is related to the position of the deformable mirror; with an increase of the distance between the deformable mirror and the output mirror of the laser the correction effect is better. For a deformable mirror with a given unit size, when the distance of correction is more than 20?m the correction effect is perfect.     

大口径光学镜面超精密加工机床的研制

设计制作了最大加工直径为φ880 mm的光学镜面超精密加工机床.该机床采用大理石床身、4轴数控联动、全气浮支承和零传动结构,以实现光学球、非球及自由形面的超精密切削.介绍了机床整体结构特点和性能参数,描述了气浮电主轴、气浮直线导轨、直驱回转工作台等关键技术及部件.该机床主轴回转精度0.05μm,直线伺服轴分辨力1.25 nm,回转工作台角位移分辨力0.009.″在硬铝和无氧铜材料上分别加工出了面形精度0.5μm、表面粗糙度5 nm的φ400 mm球面和面形精度0.5μm/φ100 mm、表面粗糙度8 nm的非球形面.