共查询到19条相似文献,搜索用时 156 毫秒
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利用衍射光学元件增加出射光束的焦深 总被引:1,自引:1,他引:0
在入射光束的孔径受限制的情况下,利用衍射光学元件来增加激光束的焦深。首先确定光阑孔径的大小、然后利用Y-G算法,在已知入射和出射光波函数的条件下,计算出衍射光学元件的位相分布。计算结果表明焦深可以比未用衍射光学元件时增加一半或更多。 相似文献
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基于蒙特卡罗模拟的NaI,BGO,LSO,GSO,YSO闪烁晶体对比研究 总被引:1,自引:0,他引:1
发射断层成像系统中大都采用闪烁晶体与光电倍增管相耦合组成的γ射线探测器。闪烁晶体的光收集效率直接影响着探测器的能量、时间和空间分辨力。为了设计更好的探测器,利用M onte Carlo方法对N aI,BGO,LSO,GSO,YSO闪烁晶体进行了对比研究,分析比较了不同表面处理、晶体尺寸,外界反射材料对光收集效率的影响。模拟结果表明:入射面为粗糙面,其余为抛光面同时外层包装上高反射率的材料可得到最大的光输出,其中YSO表现出最优的光输出性能。晶体的几何尺寸对得到高的光输出也起着非常重要的作用。 相似文献
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为研究闪电特性,设计了用于闪电实验室场景模拟的大变倍比近红外无焦激光扩束光学系统,用于模拟不同光斑尺寸的闪电单元.根据高斯光学几何法计算系统外形尺寸,合理确定了各组份的口径及光焦度;由ZEMAX软件包优化设计得到系统的光学结构参数,并对系统整体性能进行了分析评价.该系统变倍比为13,出射光束光斑均匀、无衍射环,满足研究闪电信号特性的需求.激光扩束系统的中心工作波长为777.4 nm,入射光束直径为1.0 mm,入射激光光束在步进电机驱动下连续可调,使得出射光束可从φ0.8 mm变化到φ10.6 mm.系统具有镜片少,结构简单,变焦轨迹平滑无卡滞等优点,可用于模拟不同尺寸的闪电单元. 相似文献
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应用蒙特卡罗方法模拟了三层皮肤组织中光的传输和分布情况,模拟结果得出光经过皮肤组织漫反射后的出射位置分布和出射角度分布情况;根据此模拟结果,分析和设计了一种具有特殊结构的血糖无创检测光纤探测器,此探测器在表皮和收集光纤之间设置了一组反射镜面,大部分光经镜面反射后被收集光纤收集。此设计弥补了光纤数值孔径对探测器收集效率的限制。 相似文献
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一种反射式光纤传感器的研究 总被引:5,自引:1,他引:5
为了解决传统的单端输出Y型分支结构的反射式光纤传感器易受入射光强变化、被测表面形貌不同等因素影响的问题,作者研制了一种具有两个输出端的新结构光纤传感器,并对该光纤传感器在精加工表面上的光反射特性进行了理论分析和实验研究。研究结果表明,光纤测头两输出信号之比与测量距离的变化有较好的线性关系,并能显著减少光源发光强度波动及被测表面粗糙度对位移测量结果的影响,从而有利于提高抗干扰能力和测量精度。因此,这是一种性能比较优越的非接触式微位移传感器。 相似文献
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本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。 相似文献
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本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。 相似文献
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Techniques for broadside coupling to long-range surface plasmon waves propagating along metal stripes are investigated. The baseline technique consists of evanescently coupling an optical input beam originating from a polarization maintaining fiber to the plasmon wave via a right-angle prism positioned above the metal stripe, and providing an optical output some distance away through a mirror arrangement of identical elements. The technique is modeled theoretically using plane waves and implemented to measure the attenuation of the long-range plasmon wave propagating along a metal stripe supported by a thin freestanding dielectric membrane. An alternative technique for providing an output is proposed, whereby a tipless atomic force microscope probe physically contacts the metal stripe to generate out-of-plane scattering and a multimode fiber positioned nearby is used to capture a portion of the scattered light. This technique is easier to implement than the baseline technique, resulting in attenuation measurements of significantly better quality. The goodness of fit of the best fitting linear models to the measurements was significantly improved using this technique (0.93 and 0.99), and the measured attenuations were in very good agreement with the theoretical ones (6.01% and 0.27% error). This simple technique for optical probing and coupling could be applied to other surface plasmon waveguides and possibly to dielectric waveguides with modes having sufficient field strength in their evanescent tail. Output scattering using micron-sized particles located on the metal stripe was also investigated. The stability of the experimental setup was assessed and found to be about 0.01 dB peak to peak over a few minutes at constant temperature using a reference optical signal. 相似文献
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Jean-Claude Jésior 《Ultramicroscopy》1982,8(4):379-384
Biological molecules often form micro-crystals that are in a size range that is unsuited for study either by X-ray crystallography or by electron microscopy. The method described here allows the use of most of these crystals. It consists of cutting sections through the crystal deposited on a grid after a preliminary observation in the electron microscope to determine its precise location. It allows visualization of the crystal molecular packing in any plane normal to the grid plane at the resolution usually obtained by negative staining. If the crystal is thin enough, two orthogonal views of the same crystal can be obtained. The orientation and the position of the sections along the crystal axis are precisely determined using latex particles as reference points. Crystals as small as 1 μm in length can be studied. 相似文献
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提出了紧凑型矢量光场发生器中4f系统在横向和纵向上的精确对齐方法,并进行了实验验证。将设计的特定相位图加载到矢量光场发生器中,通过调整4f系统中各元件之间的距离以及物面和像面到相应透镜的距离,以CCD采集光斑图像的锐利程度作为判据来实现4f系统的纵向对齐。以空间光调制器的相位控制区域作为参考坐标系,采用四象限图测量另外三个调制区域的光斑在横向上的坐标位移,通过在设计的相位图中预补偿测量到的坐标位移来实现4f系统的横向对齐。实验结果表明,所提出的4f系统对齐方法可以显著减小矢量光场发生器中所调制光斑的衍射效应。 相似文献
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为了优化MgO:PPLN连续光参量振荡器(OPO)的输出特性,对三镜直腔结构的内腔式OPO系统进行腔结构设计,对其同时输出高效的信号光和闲频光进行研究。采用半导体激光端面抽运Nd:YVO4晶体实现连续的1064 nm激光为基频光。对比分析了基频激光腔和OPO腔各腔镜分别采用平面镜或平凹镜的三种腔型结构的激光输出特性。基于30.5 μm的极化周期和12.4 W入射抽运功率时,获得了最高输出功率3.92 W(信号光2.6 W和闲频光1.32 W),转化效率31.6%的激光输出,对应的信号光和闲频光的中心波长分别为1549 nm和3394 nm。结果表明三个腔镜均采用平凹镜时,可有效的压缩基频激光腔在MgO:PPLN晶体上的光斑,提升基频激光的功率密度,而且基频激光腔和OPO腔的基模光斑在MgO:PPLN晶体上更好的匹配,从而提升变频效率。 相似文献
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Stoeckl C Fiksel G Guy D Mileham C Nilson PM Sangster TC Shoup MJ Theobald W 《The Review of scientific instruments》2012,83(3):033107
A narrowband x ray imager for the Cu K(α) line at ~8 keV using a spherically bent quartz crystal has been implemented on the OMEGA EP laser at the University of Rochester. The quartz crystal is cut along the 2131 (211) planes for a 2d spacing of 0.3082 nm, resulting in a Bragg angle of 88.7°, very close to normal incidence. An optical system is used to remotely align the spherical crystal without breaking the vacuum of the target chamber. The images show a high signal-to-background ratio of typically >100:1 with laser energies ≥1 kJ at a 10-ps pulse duration and a spatial resolution of less than 10 μm. 相似文献
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Geometric Theory for the Design of Multielement Optical Systems 总被引:1,自引:1,他引:0
1 Introduction Thecurrenttrendinextremeultraviolet(EUV )lithographyandsophisticatedsynchrotronradiationinstrumentationistheuseofanopticalsystemthatconsistsofseveraladvancedopticalele ments,suchasaccuratelyfiguredasphericmirrorsandvariedlinespacinggrati… 相似文献