共查询到20条相似文献,搜索用时 31 毫秒
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简要介绍了传统自适应光学系统的局限性和多层共轭自适应光学基本原理。模拟了单双层共轭校正系统的共轭高度,并结合平程与垂程(HV模型)两种传输状态对系统等晕角增益作了进一步的分析。对单层共轭系统,在20 km的传输距离内,在平程中整个区域都属于等晕角放大区,共轭高度的最佳位置在传输距离的中间(约10 km处),等晕角取极大值,增益效果较好;但垂程中增益效果变差,且等晕角放大区也仅在3.6 km之内。对双层共轭系统来说,第1层共轭高度的变形镜主要对近距离畸变波前进行校正,并对整个传输距离的等晕角影响很大,是双层共轭系统的关键因素;第2层共轭高度对远距离等晕角影响较大。 相似文献
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C.P. Wang 《Optics Communications》1975,14(2):200-204
For optical imaging through turbulence, a measure which specifies how close a given imaging system is to be isoplanatic is defined. Its defendence on the spatial resolution, seeing angle, and turbulence structure is given. The result shows that for low resolution imaging, the isoplanatic condition is usually satisfied, while for diffraction-limited imaging, the isoplanatic condition does restrict the seeing angle to be small. 相似文献
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为保证半导体激光打标机F-θ镜头的扫描质量,实现系统像高与扫描角的线性变化,需对F-θ镜头给予一定的畸变量,并使其满足等晕条件。分析F-θ镜头工作原理及像差要求,根据1 064 nm半导体激光打标机的光源成像要求选择合适的玻璃材料,合理分配每片透镜的光焦度,以保证等晕成像;根据F-θ镜头线性成像要求,计算系统总畸变量为1.6%,系统总畸变量为系统的实际桶形畸变与相对畸变量之和;在光学系统优化设计时,引入这两项优化参数,优化过程中观察系统成像变化情况。设计结果表明:系统MTF曲线接近衍射极限,F-θ镜头相对畸变小于0.36%,各视场均方根半径均小于艾里斑直径,并且整个系统70%的能量集中在直径为16 μm的圆内,系统总畸变量为1.58%,满足设计指标要求。 相似文献
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激光导引星大气湍流波前非等晕性误差的像差模式分解 总被引:2,自引:1,他引:1
激光导引星概念解决了自适应光学技术的信标问题,同时带来了无法克服的非等晕性误差。将高度聚焦非等晕性误差和角度等晕性误差统一起来考虑,分析激光导引星的大气湍流波前各阶模式的非等晕性误差,并给出了解析模型。同时分析了瑞利导星和纳导星的大气湍流波前的模式非等晕性相对误差,在没有角度偏离的情况下,90km的钠导星的模式非等晕性误差明显小于15km的瑞利导星,但是它对角度的敏感程度却远远大于端利导星。采用激光导引星的自适应光学系统用于大气湍流的校正,选择较低阶的模式校正就可以达到较好的效果,而且即使目标与导引星的偏角大于等晕角,选择低阶模式也可以达到有效的部分校正效果。 相似文献
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What is believed to be a novel holographic design for read-only memory systems allows a compact low-cost consumer drive within a 10 mm drive height, using a lensless phase conjugate readout and a combination of polytopic and angle multiplexing. A two-step mastering method enables production of high-efficiency holographic masters, and fast replication is possible by using only a series of plane-wave illuminations. Mastering and replication techniques are verified experimentally with an array of 125 holograms with no measured bit errors. 相似文献
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周视彩虹全息图中共轭像的抑制 总被引:2,自引:1,他引:1
本文从理论和实验两方面分析了共轭像的干扰问题,求得了共轭像强度对记录介质厚度及物光—参考光夹角的依赖关系,并对普通6μm干板给出了抑制共轭像的条件. 相似文献
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KNSBN:Co晶体自泵浦位相共轭特性的研究 总被引:3,自引:3,他引:0
本文报道在两块不同尺寸的KNSBN:Co晶体中实现了自泵浦位相共轭输出,通过实验验证了位相共轭反射率与入射角、入射位置以及波长有关,并给出各自的实验曲线.保持激光器工作波长为514.5nm不变,在大块晶体中可得到高达73.0%的位相共轭反射率.文章还给出共轭光的形成时间随系统光强变化关系的实验曲线,并指出自泵浦形成时透射光强和晶体表面反射光强的时间变化特性,解释了自泵浦形成的阈值特性. 相似文献
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Tatsuki Tahara Yuki Shimozato Peng Xia Yasunori Ito Takashi Kakue Yasuhiro Awatsuji Kenzo Nishio Shogo Ura Toshihiro Kubota Osamu Matoba 《Optical Review》2013,20(1):7-12
Parallel phase-shifting digital holography (PPSDH) is a technique of single-shot phase-shifting digital holography. We found that there are two problems with this technique. (1) Some extraneous noises caused by the intensity unevenness of the reference wave become slightly superimposed on the object image. (2) The conjugate image cannot be completely removed. This is because the object wave causes the phase-shift error by illuminating an image sensor with a large incident angle. To solve these problems, we propose an algorithm for removing residual 0th-order diffraction and conjugate images in PPSDH. In the proposed algorithm, we modified phase-shifting interferometry in order to work through the unevenness of the intensity distribution and applied the Fourier transform technique to PPSDH to remove the residual conjugate image. The effectiveness of the proposed algorithm was experimentally verified. 相似文献
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《Journal of magnetism and magnetic materials》2001,234(3):545-555
The force exercised on a permanent magnet (PM) in a nonuniform field (gradient force) is dependent on the magnetization orientation of the magnet. In this paper, it is shown theoretically that the gradient force is greatest when the magnetization through the magnet, or at least at its surface, is collinear with the external field. The formulae for calculating the force between an axis-symmetric optimal magnet and a coaxial axis-symmetric coil are presented. Using the finite element method (FEM), calculations of the magnetic field distribution of an optimal cylindrical magnet and some its approximations are performed. The forces between these magnets and a pancake coil are computed and compared. For a system consisting of a magnet with a height of 1 unit and a diameter of 2 units and magnetization invariant in field and an annular pancake coil with a diameter of 2.4 units, a thickness of 0.2 units, an inner diameter of 0.4 units and a distance from the magnet of 0.2 units, the force on the optimal magnet was 1.44 times greater than the force on an axially magnetized magnet of the same size and magnetization magnitude. The optimal magnetization may be approximated by magnetization inclined at a constant angle to the axis and by a combination of axially and radially magnetized sections. With magnetization at a constant angle to the axis in the axis plane, the force was greatest when the angle was about 45°, being 1.38-fold compared to the force on an axially magnetized magnet. When the magnet was composed of an axially magnetized cylindrical core and a radially magnetized outer ring, the force was greatest when the volume of the core was approximately equal to the volume of the ring, being 1.26-fold compared to the force on an axially magnetized magnet. The optimal magnet and its approximations also provided a reduced stray field. A short review of methods of the fabrication of permanent magnets (PMs) with a continuous variation of the magnetization orientation and with radial magnetization orientation is given.The results of this study can be used to design linear electromagnetic (micro)actuators. 相似文献
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从BaTiO_3晶体自泵浦相位共轭透射光束的出射角随泵浦光束入射角的变化,相位共轭透射光束在晶体中的光路,以及相位共轭透射光束的透射率随泵浦光束和晶体c轴夹角的变化等几方面研究了BaTiO_3晶体自泵浦相位共轭中的透射效应,根据实验结果肯定了自泵浦相位共轭中透射现象的存在. 相似文献