大口径望远镜Coude光路光机结构设计研究

Coude光路是大口径望远镜光学系统必要的组成部分,它将主望远镜的光束进行传递,以使其进入望远镜机下Coude实验室,与子光学系统相耦合.在Coude光路中,存在多块折转反射镜,反射镜之间的相对位置关系影响着系统的成像质量.因此如何保证光学元件之间的位置关系,成为光机结构研究的关键问题.根据系统要求分析并设计了各类型调...     

正支共焦非稳激光谐振腔的数值模拟

谐振腔内像差对光束质量的影响十分明显，直接导致激光器的输出功率及光束质量的下降。对理想状态以及受相位倾斜、像散像差扰动后的正支共焦非稳腔进行了数值模拟分析。计算机仿真结果表明，采用数值迭代分析法可以很好地对正支共焦非稳腔的模式特性进行研究，从而为自动调腔或采用自适应光学技术对谐振腔内像差进行自动补偿提供了理论基础。     

利用腔内凹面镜控制输出光束稳定性的激光系统

本文给出了一种控制正支共焦非稳腔输出光束稳定性的激光系统.利用哈特曼波前传感器实时测量谐振腔内的倾斜扰动像差,基于该像差信号,采用一台步进电机作为主控器,并采用比-积分一微分(PID)控制算法控制一块高反射率的凹面腔镜完成腔内倾斜扰动的自动校正.理论和实验研究表明:本系统能够快速稳定地控制正支共焦非稳腔失调引起的倾斜像差,实现正支共焦非稳腔输出光束的自动稳定.     

集成光学陀螺环形谐振腔的优化设计与制备

利用广角有限差分光束传播法(WA-BPM)对集成光学陀螺(10G)用掺锗的二氧化硅光波导环形谐振腔进行了优化设计,详细分析了谐振腔的主要性能参数精细度F与各种损耗及光强耦合系数的关系. 在优化设计基础上,在硅基底上利用等离子体增强型化学汽相沉积(PECVD)法与反应离子刻蚀(RIE)制作了掺锗的SiO2光波导环形谐振腔.经测试,在1 550 nm波长处,光波导传输损耗为0.02 dB/cm,环形谐振腔内总传输损耗仅为0.1 dB/circuit,可为今后集成光学陀螺的小型化和高灵敏度提供理论参考.     

高能激光发射系统光束监测与装调的新方法

高能激光束能量高,波长较长,无法用常规的光电探测器进行接收.为了实现高能激光发射系统中激光束的监测和系统的快速高精度装调,采用间接测量的方法,将激光束的监测转换为激光谐振腔出射镜的监测,并且通过使用光路切换镜,用He-Ne激光束代替高能激光束来完成整个系统的装调.对光束监测系统、装调辅助系统、靶标镜以及光路切换镜等辅助设备的工作原理和使用方法做了简单的介绍.为考察方法的有效性,结合CO2激光发射系统进行了精度分析.结果表明,使用本方法装调后,光轴平行度误差可达到15.9",满足设计指标的20".     

基于Lighttools的激光陀螺光学仿真

LightTools是一个全新的具有光学精度的交互式三维实体建模软件体系,在系统初步设计、复杂系统设计规划、照明系统设计分析等方面发挥重要作用。介绍一种基于Lighttools的激光陀螺光学仿真,依靠Lighttools完成对激光陀螺光学模型的建立,并对模型可靠性进行测试,从而在实际的陀螺生产中提供设计指导。     

压电陶瓷驱动电源及其在激光陀螺扫模中的应用

对压电陶瓷微位移器驱动电源与环形激光陀螺腔长调节原理进行了分析 ,在此基础上 ,设计了微机控制 0～ 30 0 V电压连续可调压电晶体驱动电源 ,并将其应用于自行设计的环形激光陀螺自动扫模系统。实验获得的扫模曲线表明 ,该驱动电源能够满足环形激光陀螺扫模系统的要求     

远红外自由电子激光光学谐振腔

光学谐振腔是自由电子激光器的一个重要部分，远红外波段自由电子激光的光学腔由两个相距２７６７ｍｍ，曲率半径分别为１９３９ｍｍ和１１６８ｍｍ的凹圆柱面反射镜Ｍ１（上镜）和Ｍ２（下游镜）相对地与摇摆器的扁矩形真空室相连接的光镜室而构成。为满足产生自由电子激光的要求，必须使摇摆器的机械中心轴、电子整整不运动轨迹包络的中心轴和两反射镜镜面中心构成的光轴共线，且反射镜应能在真空中作一定范围的六维，即Ｘ，Ｙ，Ｚ     

机抖激光陀螺稳频控制技术

激光陀螺的工作中心频率作为激光陀螺的工作计量基准,其频率的稳定性对激光陀螺的测量精度有着直接的影响．稳定激光陀螺工作中心频率最为有效的方法就是采用主动腔长补偿控制．在对腔长控制原理和方法介绍的基础上,提出了将激光陀螺输出光强信号进行交直流分量分离独立控制的方法,并给出了系统的硬件设计框图,最后介绍了软件设计流程．测试结果表明漂移均方差在0．4°·h-1以内,满足系统的使用要求．     

一种非稳腔激光器光束填充因子测量方法

基于CCD探测技术，设计了对激光非稳腔光束填充因子的测量系统，可精确地测量强激光近场光强分布，并运用Matlab软件对测试数据进行处理，得到光束填充因子。与量热阵列测量法相比，该方法具有测量准确度高的优点。     

Two-deformable-mirror concept for correcting scintillation effects in laser beam projection through the turbulent atmosphere

A two-deformable-mirror concept for correcting scintillation effects in laser beam projection through the turbulent atmosphere is presented. This system uses a deformable mirror and a Fourier-transforming mirror to adjust the amplitude of the wave front in the telescope pupil, similar to kinoforms used in laser beam shaping. A second deformable mirror is used to correct the phase of the wave front before it leaves the aperture. The phase applied to the deformable mirror used for controlling the beam amplitude is obtained with a technique based on the Fienup phase-retrieval algorithm. Simulations of propagation through a single turbulent layer sufficiently distant from the beacon observation and laser beam transmission aperture to cause scintillation shows that, for an ideal deformable-mirror system, this field-conjugation approach improves the on-axis field amplitude by a factor of approximately 1.4 to 1.5 compared with a conventional phase-only correction system.     

Use of null optics for monitoring the optical alignment of a beam director

The use of null optics is proposed as a new concept for monitoring the optical alignment of a beam director. Null optics consist of a primary mirror and an annular mirror just outside the aperture of the secondary mirror. The characteristics of the proposed null optics are investigated with the designed sample of a two-mirror system with an effective aperture of 275 mm. The results show that null optics yield four times the amplification with respect to the alignment errors of the secondary mirror; however, they have low residual aberration sensitivity to misalignment. Therefore null optics can be used successfully as the alignment monitoring apparatus of a beam director.     

Off-axis mirror based optical system design for circularization, collimation, and expansion of elliptical laser beams

In this paper, we present two optical system design methods for beam circularization, collimation, and expansion of semiconductor laser output beam for possible application in LIDAR systems. Two different optical mirror systems are investigated: an off-axis hyperbolic/parabolic mirror system and an off-axis parabolic mirror system. Equations specific to these mirror systems are derived and computer package programs such as ZEMAX and MATLAB are used to simulate the optical designs. The beam reshaping results are presented.     

Polarimetric calibration of large-aperture telescopes. I. Beam-expansion method

A concept is described for the high-accuracy absolute calibration of the instrumental polarization introduced by the primary mirror of a large-aperture telescope. This procedure requires a small aperture with polarization-calibration optics (e.g., mounted on the dome) followed by a lens that opens the beam to illuminate the entire surface of the mirror. The Jones matrix corresponding to this calibration setup (with a diverging incident beam) is related to that of the normal observing setup (with a collimated incident beam) by an approximate correction term. Numerical models of parabolic on-axis and off-axis mirrors with surface imperfections are used to explore the accuracy of the procedure.     

Multipass annular mirror system for spectroscopic studies in shock tubes

Abstract

A fundamentally new multipass reflecting mirror system for studies in shock tubes is designed. Conducting optical absorption measurements in shock tubes when modelling processes of controlled combustion is necessary. The results of these optical studies facilitate working out recommendations on efficient and non-polluting burning of natural fuels in industry. The basic component of the suggested multipass optical system is an annular reflector in the form of a spherical concave belt joined as a separate section to the shock tube. Radiation from a source directed inwards the annular reflector traverses the tube section many times reflecting from the mirror surface which thereby increases the thickness of the absorbing layer. Because of the absence of bulging edges inside the reflector, no perturbations appear in the flow. The system design allows simple control of the optical path length. Equations relating the angular aperture of an incident beam to the chosen parameters of the annular reflector are reported. A formula for the number of beam passes as a function of the incidence angle of the beam entering the reflector is derived.     

An interference method for measuring parallelism of miniature optical components

A method for measuring parallelism of transparent optical components with small aperture size is described. It uses a Haidinger-type laser interferometer adapted for the measurement of optical components with millimeter and sub-millimeter aperture size. The method is based on the measurement of the optical thickness variation when the plate under test is translated across a focused laser beam. Measurement results for optical parts with 0.8 mm–10 mm aperture size are presented.     

大数值孔径微透镜阵列激光扫描

提出微透镜阵列与转镜相结合的大口径激光光束扫描方法。采用机械制模法制作微透镜阵列模板 ,然后采用模压法制作光学微透镜阵列 ,其子口径为 2 mm× 2 mm,数值孔径为 0 .2 ,阵列数为 8× 8。并进行了扫描测试实验 ,扫描角达± 6.56°。     

HL-2A托卡马克装置CXRS光学系统设计

电荷交换复合谱(CXRS)是一项先进的测量托卡马克等离子体温度及空间分布的方法。针对我国HL-2A托卡马克装置上CXRS光谱采集系统对宽光谱范围(470?660nm)、大视场(535.34mm)、宽光束(直径110mm)、高空间分辨(14道)以及与后续导光光纤数值孔径(0.22)匹配等要求,应用ZEMAX光学设计软件优化设计了一片反射镜与四片透镜组合的光学系统,并通过将像面倾斜的方法进一步减小了像差。模拟计算表明像面最大弥散斑RMS半径为88.14?m,像方数值孔径0.217,很好地满足了使用需要。     

Modes of resonators with dispersive phase-conjugate mirrors

We investigate the transverse and longitudinal modes of a resonator consisting of a spherical mirror, a Gaussian aperture, and a dispersive phase-conjugate mirror (PCM). The photorefractive PCM introduces spatial dispersion in the form of lateral and focal shifts along with temporal dispersion. For both degenerate and nondegenerate operation, the decentered Gaussian beam was found to be a mode whose peak intensity is displaced from the resonator axis. In the nondegenerate case, the components of a mode oscillating at a pair of frequencies that are up and down shifted from the pump frequency by the same amount have different spatial distributions, so that the intensity pattern moves periodically across the output mirror. The resonance frequencies of the longitudinal modes are calculated numerically.     

An implementation of synthetic aperture focusing technique in frequency domain

A new implementation of a synthetic aperture focusing technique (SAFT) based on concepts used in synthetic aperture radar and sonar is presented in the paper. The algorithm, based on the convolution model of the imaging system developed in frequency domain, accounts for the beam pattern of the finite-sized transducer used in the synthetic aperture. The 2D fast Fourier transform (FFT) is used for the calculation of a 2D spectrum of the ultrasonic data. The spectrum is then interpolated to convert the polar coordinate system used for the acquisition of ultrasonic signals to the rectangular coordinates used for the presentation of imaging results. After compensating the transducer lobe amplitude profile using a Wiener filter, the transformed spectrum is subjected to the 2D inverse Fourier transform to get the time-domain image again. The algorithm is computationally attractive due to the use of 2D FFT. The performance of the proposed frequency-domain algorithm and the classical time-domain SAFT are compared in the paper using simulated and real ultrasonic data.