大口径天文薄镜面磨制试验

介绍了采用薄镜面主动支撑技术来加工大口径天文薄镜面的试验情况。试验镜为一弯月型球面反射镜．直径为Ф1035mm,镜面曲率半径为3220mm,径厚比约为40：1。在磨制过程中,有55个分离支撑点支撑存镜子背面。支撑点的位置与支撑力的大小通过有限元分析计算确定,其中3个为固定支撑点．另外52个为主动支撑点。每个支撑点位置设置了力促动器,调节力促动器加力的大小。可以主动改正镜面的低频误差。加工后最后达到的面形精度：λ=632．8nm,面形误差(RMS)小于等于λ／21．5,局部高频误差(RMS)小于等于λ／23。试验证明所采用的方法适合于大口径天文薄镜面的加工。     

激光诱导和化学镀铜制备太赫兹偏振器和滤波器

利用激光诱导与化学镀铜的方法在聚酰亚胺薄膜上制备了太赫兹线栅偏振器和带阻滤波器,用太赫兹时域光谱系统对所制备的器件进行了测试。测试结果表明,该方法制备的太赫兹线栅偏振器在0.2～1.5 THz范围内的消光比优于20 dB,耶路撒冷十字结构带阻滤波器的3个中心频率分别为0.41、1.07、1.47 THz。实验结果与时域有限差分法的仿真结果基本相符。研究表明激光诱导与化学镀铜是一种简单灵活且能有效地制备太赫兹器件的方法。     

像素偏振片阵列制备及其在偏振图像增强中的应用

像素偏振片阵列在实时测量光的斯托克斯参量方面具有重要的应用.本文设计和制作了基于金属铝纳米光栅的像素偏振片阵列,制作工艺基于电子束曝光技术.偏振片阵列单元尺寸为7.4μm,每相邻2×2单元的透偏振方向分别为0,7π/4,π/2和3π/4.光栅周期为140 nm,占空比为0.5,深度100 nm,光栅面型为矩形.像素偏振片阵列的扫描电子显微镜照片显示,制备的偏振片阵列的金属纳米光栅栅线无断线、无交叉、无杂物污染,光栅栅线结构平直,厚度均匀,满足理想矩形面型.采用偏振光作为照明光的光学显微镜拍摄图片显示,像素偏振片阵列整体形状规则,具有很好的偏振特性,最大偏振透射率可达到79.3%,消光比可达到454.将像素偏振片阵列与CCD(charge coupled device)集成在一起,采集单帧图像即可计算图像的斯托克斯参量,从而得到拍摄物体线偏振度图像和线偏振角图像,实现了偏振增强,可应用于目标反隐和识别.     

Fabrication Techniques and Characteristics of Ultra-Thin Optical Polarizing Films Using Gold Island Films

Fabrication techniques of ultra-thin optical polarizing films using gold island films have been investigated for the near-infrared region. The polarizing films are fabricated by stretching the periodic multilayers consisting of gold island layers and glass layers. We have experimentally investigated the optimum fabricating conditions necessary to induce large optical anisotropy into the gold island layers and have formed submicrometer-thick polarizing films with an extinction ratio of ≥20 dB in a near-infrared region longer than 800 nm. These polarizing films could be useful micro-polarizers for fiber-embedded in-line optical devices, micro-optics, and hybrid integrated optics.     

Fabrication and Patterning of Submierometer-Thick Optical Polarizing Films for 800 nm Using Stretched Silver Island Multilayers

Stretched silver island multilayers have been investigated for patterned optical polarizers for the wavelength of 800 nm. Submicrometer-thick optical polarizing films are fabricated by stretching periodic multilayers consisting of silver island layers and Pyrex layers at the temperature of 660°C. As the optical anisotropy of the optical polarizing film is lost by heating at a temperature higher than the stretching temperature, the fine non-polarizing areas can be deliberately and easily formed on the optical polarizing film by laser irradiation with high power density. We have successfully formed various non-polarizing areas on the optical polarizing film with a 1 W-class carbon dioxide laser. The demonstrated fabricating techniques of deliberately patterned optical polarizing films should be useful for novel optical computing and sensing devices.     

大型光学镜面的多点支撑方案分析

在大型光学系统中使用薄型镜面以减轻大口径光学镜面的重量，但由于薄镜面在重力作用下形变严重，需要选择适当的支撑方式来维持光学镜面的面形。通过对支撑方式的分析，采用有限元仿真，讨论了支撑点分布方式、支撑分布位置和支撑点数三方面对镜面形变的影响，从而得出支撑点均匀分布优于非均匀分布；支撑点数一定时，镜面形变主要由支撑点位置决定；10个支撑点以上镜面形变相对较小，继续增加支撑点并不能使镜面最大形变得到显著改善同时会引起镜面波纹起伏增加。     

Mode Distribution and Bandwidth Characteristic of Arbitrarily Trapezoidal-Groove Guide for Millimeter Waves

The modes TE and TM of arbitrarily trapezoidal-groove guide are analyzed by using the mode-matching method. The mode TE₁₁ is the dominant mode of the trapezoidal-groove guide under different conditions. The bandwidth characteristic and the operation condition for the single dominant mode are discussed. The obtained conclusions are of very important significance in theoretical study and practical application of trapeziodal-groove guides for millimeter waves.     

Studies on Fast Algorithm for the Scattering of a Large Array of Waveguide-Fed Wide-Slot Antennas in Millimeter Wave Region

We present an effective numerical technique to characterize the scattering of wide-slot antennas fed by waveguides with arbitrary terminations in terms of the method of moment (MoM) and the mixed potential integral equation (MPIE). In particular, the precorrected-fast Fourier transform (P-FFT) eliminates the need to generate and store the usual square impedance matrix andthus leads to speed up the matrix-vector multiplication in the resultant system. This property makes the Rao-Wilton-Glisson (RWG) functions to be useful in simulating electrically large-scale problems. In addition, the scattering from the finite ground surfaces is accounted for in the total scattered field by using the method of equivalent edge currents. The numerical results are presented and compared with both the traditional method of moment results obtained using the entire-domain basis functions and the experimental results, to demonstrate the proposed method to be a good candidate for study on the scattering of arbitrary wide-slot large array.     

大视场大相对孔径水下专用摄影物镜的设计

分析了大视场大相对孔径水下专用摄影物镜的设计特点.基于反摄远结构引入一个高次非球面设计了相对孔径为1/1.4,水下全视场66°,焦距11.85 mm,光谱响应范围0.48～0.60 μm,采用平面水密壳窗的水下专用摄影物镜.全视场MTF在空间频率42 lp/mm时高于0.4.与相同技术要求下全部采用球面透镜的设计进行比较,表明该摄影物镜结构更简单,成像质量也更优异,能够满足深水微光摄影物镜对大视场、大相对孔径、小型化、轻量化的需求.     

Large aperture phase-coded diffractive lens for achromatic and 16° field-of-view imaging with high efficiency

Diffractive lenses (DLs) can realize high-resolution imaging with light weight and compact size. Conventional DLs suffer large chromatic and off-axis aberrations, which significantly limits their practical applications. Although many achromatic methods have been proposed, most of them are used for designing small aperture DLs, which have low diffraction efficiencies. In the designing of diffractive achromatic lenses, increasing the aperture and improving the diffraction efficiency have become two of the most important design issues. Here, a novel phase-coded diffractive lens (PCDL) for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally, and it also possesses wide field-of-view (FOV) imaging at the same time. The phase distribution of the conventional phase-type diffractive lens (DL) is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL. The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm, a focal length of 100 mm, and a cubic phase coding parameter of 30π. Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16° with over 8% focusing efficiency, which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions. This work provides a novel way for implementing the achromatic, wide FOV, and high-efficiency imaging with large aperture DL.     

The Improvement of PML Approach for the Calculation of Microwave and Millimeter Waves Circuit

The improved PML absorbing boundary condition have been introduced in this paper. The reflection coefficient of the absorbing boundary condition is less than the reflection coefficient of Berenger's PML algorithm. And in order to validate the theory and its effectiveness, We have applied the absorbing boundary condition to the calculation of microwave and millimeter waves circuit and get its reflection coefficient S ₁₁. The numerical result is shown in this paper.     

大芯径大数值孔径阶跃光纤传导模特征方程求解

导出了相邻阶第二类变型贝塞尔函数的比值在小宗量的逼近形式,利用Lentz—Thompson方法计算相邻阶第一类贝塞尔函数的比值在小宗量的值,计算精度为浮点数系统的最低有效位。从而解决了求解大芯径、大数值孔径阶跃光纤的特征方程时．贝塞尔函数溢出双精度浮点数表示范围的问题。分别对多模石英光纤和大芯径大数值孔径的聚合物光纤的传导模特征方程进行了求解,石英光纤的传导模特征值计算结果与Optiwave公司的软件一致;对于聚合物光纤,算法给出了所有模式的计算结果,其中模式角向序数小于70的计算结果与Optiwave公司的软件一致,而Optiwave公司的软件不能计算角向序数大于70的模式。     

Zone-Plate Interferometer for Measuring the Shape Error of Mirrors with Large Numerical Aperture and Steep Asphericity

A compact zone-plate interferometer is developed to measure the shape error of concave mirrors. A diffracted light of (0, 0) and that of (-1, -1) or (+1, +1) are used in the interferometer. The interferometer enables us to measure the shape error of mirrors with a large numerical aperture and a steep asphericity. The shape errors of a spherical mirror and a parabolic mirror are measured by the interferometer, and that of the former agrees well with that measured by Fizeau interferometer. Methods for adjustments of zone plates and the mirrors being tested are proposed to perform precise measurements of the mirror shapes.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994.     

物理实验大平台建设实践与思考

本文介绍了中国石油大学(华东)物理实验教学中心开展物理实验大平台建设与实践情况。物理实验大平台建设以"整体规划、统一建设、集中管理、资源共享、促进创新"为指导思想,构建"一个中心,两个平台、多个模块"实验室运行体系,提高了实验室建设和运行水平,促进了教学、科研和人才培养。     

机载光电吊舱嵌入式大容量视频存储和回放系统的设计

受地球曲率半径的限制,地面测控站在一定距离之外便无法接收到无人机光电吊舱获取的图像信息。为解决这一问题,设计了一种嵌入式大容量视频存储和回放系统。该系统采用DSP＋FPGA的硬件架构,以NAND Flash大容量存储技术为基础,结合JPEG2000实时编解码芯片ADV202进行视频数据的压缩和解压。该系统录像时间可达30min,存储可靠,回放图像清晰,满足了无人机对探测目标的影像存储和回放需求。     

用于获取大调制度的驻波型电光调制器的设计与制作

设计并制作了一种采用微波驻波电极的电光调制器,该调制器被用于光谱展宽。通过非周期极性反转方法,在１６．２５ＧＨｚ的调制频率下实现了微波驻波与光波的相位匹配,从而获得了大调制度。实验中光谱展宽达到２．５ＴＨｚ。     

Implications for Cognitive Quantum Computation and Decoherence Limits in the Presence of Large Extra Dimensions

An interdisciplinary physical theory of emergent consciousness has previously been proposed, stemming from quantum computation-like behavior between 10⁹ or more entangled molecular qubit states (microtubulin). This model relies on the Penrose-Diósi gravity-driven wavefunction collapse framework, and thus is subject to any secondary classical and quantum gravity effects. Specifically, if large extra spatial dimensions exist in the Universe, then the resulting corrections to Newtonian gravity cause this model to suffer serious difficulties. It is shown that if the extra dimensions are larger than 100 fm in size, then this model of consciousness is unphysical. If the dimensions are on the order of 10 fm in size, then a significantly smaller number of microtubulin than originally predicted are required to satisfy experimental constraints. Some speculation on evolution of consciousness is also offered, based on the possibility that the size of these extra dimensions may have been changing over the history of the Universe. PACS numbers: 87.16.Ka, 03.67.Lx, 04.50.+h.     

Validity and Accuracy of Equivalent Circuit Models of Passive Inductive Meshes. Definition of a Novel Model for 2D Grids

Accuracy of equivalent circuit models of periodic grids is investigated in amplitude and phase in the visible region. The grids studied here are one-dimensional (1D) and two-dimensional (2D) inductive thin metal meshes. They are located in free space and are illuminated by a plane wave under normal incidence. The range of validity and the accuracy of conventional circuit models are defined by comparison with rigorous results obtained with the Finite-Difference Time-Domain (FDTD) method. In particular, it is shown that electrical models of 1D grids are accurate, whereas equivalent circuits of 2D grids should be used very cautiously. Then, a new formulation is proposed to overcome this major drawback. In the non-diffraction region, the agreement between our model and the FDTD results is within 2% for the power reflectivity and 1° for the phase over a very wide range of strip widths.     

Characterization of hybrid organic and inorganic functionalised membranes for proton conduction

Titanium zirconium phosphate and organic polymer hybrid (poly-vinyl alcohol, (3-glycidoxypropyl)-trimethoxysilane and ethylene glycol) based membranes were investigated for their potential application as proton conductors. The hybrid materials were characterized by XRD, FTIR, SEM, TGA and impedance spectroscopy analysis. It was found that embedding of functionalised inorganic particles (TiZrP) into composite polymer matrix allowed for some crystallinity formation, and cross-linking of hydroxyl groups during annealing or reactions within the organic and inorganic phases during synthesis. A complex structure was formed, as many FTIR peaks were masked by more defined peaks assigned to P–O–R bonds. The high concentration of phosphorus in the TiZrP (1:1:9 molar ratio) samples resulted in more hydrophilic particles. This was further reflected in the hybrid membranes as the water losses increased from 13 to 25 wt.% as a function of the TiZrP content changing from 10 to 50 wt.% in the final hybrid membrane, respectively. As a result, proton conductivity increased by two to three orders of magnitude from blank (organic phase only) membranes (2.61 × 10^− 5 S cm^− 1) to TiZrP hybrid membrane (2.41 × 10^− 2 S cm^− 1) at 20 °C. Proton conduction changed as a function of temperature and the Ti1Zr1P9 particles content, mainly attributed to the membrane ability to retain water, thus complying with the Grotthus mechanism.     

Fabrication and Characterization of a Fiber-Optic pH Sensor for the pH Range 2 to 13

Fabrication and characterization of a fiber-optic pH sensor based on evanescent field absorption and immobilization of ethyl violet dye on the unclad core of the fiber using sol-gel technique have been reported. The probe has been demonstrated to operate in the pH range 2 to 13. The operating range is the largest among those reported in the literature by using a single pH-sensitive dye. The sensitivity of the sensor increases with the increase in the length of the probe. The response of the probe depends on the ionic strength and the temperature of the fluid. This suggests that the pH sensor developed by us is likely to perform best under well-defined sample conditions.