共查询到20条相似文献,搜索用时 93 毫秒
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液晶光阀实时图像变换实验的新内容 总被引:1,自引:0,他引:1
以网格状物体为例。介绍了空间滤波的原理;以计算傅里叶变换全息为例,介绍了罗曼Ⅲ型和李奇型2种编码原理.利用液晶光阀图像变换光学系统进行了空间滤波实验以及计算全息图的光学模拟再现实验.实验结果与计算机仿真结果相吻合.在原液晶光阀实时图像变换实验中增加了空间滤波和计算全息2个新内容,使原实验的教学内容得到扩展. 相似文献
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用谱方法数值模拟槽道内的气固两相流动 总被引:1,自引:0,他引:1
在数值模拟领域内,谱方法具有收敛快、分辨率高和精度高的优点.谱方法处理边界方便,随着数值方法的改善和计算机的发展,它在数值模拟中的作用愈加重要.这里采用谱方法数值求解三维N—S方程,用这一方法计算了直槽道内流体的流动.计算得到的层流和湍流结果与理论结果符合地较好.在此基础之上进一步模拟了几种不同槽道内的三维粘性流体层流流动,特别在弯曲槽道内的流动计算中,发展了源项处理方法,正确地反映了弯曲固壁对流体流动的影响.通过对湍流计算获得的脉动速度场的统计可以得到湍流运动的许多统计量,正确地反映了湍流运动的特征,说明可以用模拟得到的流场来代替真实的流场.进行了气固两相流动的研究,由直接模拟得到的流体瞬时速度场对固体粒子的作用进行了粒子运动的模拟计算,得到了颗粒在真实流场中运动的浓度,轨道等有用信息和运动特性,得到了令人鼓舞的结果. 相似文献
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用中子源模拟粒子加速器,以MORSE程序分析计算由于天空反散射引起的中子剂量当量的变化规律,揭示了天空反散射的实质,计算结果可供加速器或核设施环境评价和防护设计使用.计算模型采用将中子源置于空心圆柱体中,圆柱体分为有顶盖屏蔽和无顶盖屏蔽两种情况.中子源能量分别为2.38MeV、14Mev和巨共振中子.中子源为各向同性.此外,还分析计算了不同的发射立体角和不同散射介质的影响. 相似文献
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Formulations for the total fluorescence intensity of fluorescent microspheres in slabs of cardiac tissue were determined experimentally
and theoretically. The tissue depth, at which the slab can be considered as a semi-infinite turbid medium, and critical layer
thickness, which accounts for the most emission intensity were evaluated to be 8–9 and 3–5 mm, respectively, for the cardiac
tissue. When fluorescent microspheres are linearly distributed across the slab depth, the mean absorption of them is proportional
to the sum of their normalized total emissions in the slab excited from both sides. The formulations may be used for the fluorescence
images analysis of cardiac and other biological tissues. 相似文献
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生物组织中光子微区扩散理论研究 总被引:1,自引:0,他引:1
为合理描述生物组织中光子微区的扩散情况,提出在相函数中引入独立控制参量来改进现有的一般扩散近似理论。以平板结构为例,分别利用改进的一般扩散近似理论、标准扩散近似理论以及一般扩散近似理论,对光子在不同厚度中的扩散进行数值模拟,并与蒙特卡罗方法的模拟结果进行了比较,从而论证了改进的一般扩散近似理论能很好地描述生物组织中光子微区扩散。在此基础上,进一步探讨了系统参量对独立控制参量的影响。结果表明:最佳独立控制参量会随着数值孔径的增加而下降、随着光束半径的增加而增加。本研究对微区生物组织光学特性测量技术的研究具有重要的指导意义。 相似文献
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Data relating photon migration in human tissue can be obtained from experiments in which laser light is injected into one face of a finite slab of tissue and detected at the opposite face. From the results of such experiments one would like to infer optical properties of the underlying tissue which are related to its biological properties. Random walk theory has been successfully applied to the translation of such data into the physical parameters that characterize properties of the tissue. We here outline a technique based on the theory of random walks for analyzing how well time-resolved transillumination experiments may be expected to perform for detecting hidden inclusions which have a greater absorption than surrounding tissue. We use an asymptotic evaluation of exact results to determine the degree to which detection is possible. 相似文献
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Yb:YAG and Nd:YAG edge-pumped slab lasers 总被引:9,自引:0,他引:9
Experimental demonstrations of two edge-pumped zigzag slab lasers are presented. The Nd:YAG slab laser generated 127 W of multimode output power with 300W of pump power. Preliminary results with a Yb:YAG slab produced 46 W of output power with 315W of pump power. The edge-pumped slab design permits symmetric conduction cooling and efficient pump absorption and accepts large-numerical-aperture pump sources. 相似文献
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高热负荷固体激光介质的热效应已经成为制约激光器功率进一步提高的严重障碍,只有对激光介质进行有效的冷却才能保证其安全运行。以不均匀换热系数模型为基础,研究了具有非均匀内热源的侧面双向抽运板状激光介质在狭窄通道强制对流冷却情况下的耦合换热问题,对热汇冷却方案下介质的温度分布和热应力分布进行了数值模拟和分析,并对复合介质、蓝宝石和金刚石三种热汇材料进行对比。结果表明,忽视换热系数的非均匀性将导致应力计算结果偏低。对于侧面抽运、侧面冷却的激光介质,金刚石热汇冷却方案最佳,蓝宝石热汇方案次之,而复合介质方案不宜采用。 相似文献
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在氙灯放电泵浦过程中,放大器片腔内材料在高强度氙灯光辐照下,存在显著的热解过程,产生大量的微米级悬浮粒子。在两种实验条件下对粒子数进行了测量:一是放大器氙灯泵浦结束之后悬浮粒子的自然消散过程;二是氙灯泵浦结束之后利用大气流量的超纯氮气冲洗片腔之后的粒子数测量。研究结果表明,正常情况下,氙灯泵浦结束后片腔洁净度达到了10~50万级气溶胶的水平(在粒子直径Φ 0.5 μm的水平上)。利用大气流量的超纯N2气冲洗片腔能够在短时间内显著地提高片腔的洁净度。 相似文献
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Yue Dong Jifeng Zu Liqun Hou Xianhua Yin Tao Zhang Yalong Gu Zhigang Liu Jianqiang Zhu 《中国光学快报(英文版)》2006,4(6)
Approximate formulas of transient temperature and stress distributions in the slab of a two-side pumped heat capacity laser are attained by solving the heat diffusion equation. Based on the formulas, the distributions of temperature and stress during the pump period of a two-sided symmetrically laser diode array (LDA) pumped Nd:GGG slab laser with 5-kW average output power are numerically simulated. The results show that the temperature in the slab will averagely increase by more than 70 ℃ after operating for 10 seconds; the stress and maximum of the temperature difference in the slab are about 30 MPa and 24 ℃, respectively. The thermal induced effects are discussed also. 相似文献