共查询到18条相似文献,搜索用时 78 毫秒
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有的教科书在“安培力、磁感应强度”一节中,为了说明安培力现象和安培力大小的决定因素,介绍用4根导线把1根直导线悬吊在3个并列的蹄形磁铁两极间来进行实验演示,导线通电后,根据导线摆动的角度来比较安培力的大小. 相似文献
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看得见的超声波演示实验 总被引:2,自引:2,他引:0
利用超声波能使光发生衍射的原理,将声光结合起来,以演示超声的直线传播、聚焦、反射、折射等特性,使学生直观地、形象地看到超声波的各种物理现象 相似文献
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C.K.Gamini Piyadasa 《Optics Communications》2012,285(24):4878-4883
The paper shows that the boundary diffraction wave originating at an edge is an omnidirectional cylindrical wave. The experimental set-up used to demonstrate this property employs a He-Ne laser beam. The beam is split into three beams using a glass plate. One of the beams passes straight through, the second beam passes through the glass plate and the third beam is the reflected beam. It is shown that the interference patterns are observed in all three beams. Analysis of these patterns shows that the boundary diffraction wave originating from the edge is an omnidirectional cylindrical wave. This analysis also provides strong evidence that the boundary diffraction wave travels not only within the beam where it originates but also to the neighboring coherent beam. The energy re-distribution was also shown to be dependent on the wavelength of the incident light beam and hence provides further evidence as to why longer wave lengths disperse more compared to shorter wavelengths in white light diffraction by an edge. 相似文献
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针对直边衍射效应造成的图像边缘退化问题,建立边缘退化模型。从菲涅尔直边衍射理论出发,基于信号与系统理论的图像边缘退化数学描述方法,分析了造成图像边缘退化的原因。通过分析不同光源波长和成像物距下直边衍射强度分布曲线的特点,构造简单函数实现衍射光强分布的近似,进而得到退化系统传递函数;利用退化系统传递函数构造滤波器对获取图像的边缘进行恢复,从而提高尺寸测量精度。实验结果表明:经边缘恢复方法校正后的测量结果误差约为0.02 mm,相对未校正数据的测量结果误差减小0.04 mm,提高了尺寸测量精度。 相似文献
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根据半波带法的思路,介绍了利用计算机课件演示对单缝夫琅和费衍射的条纹光强与衍射角之间的关系,以便有效地化解教学难点,帮助学生对该知识点形成清晰的认识和深化理解,同时对课件制作要点作了简要说明。 相似文献
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利用球面波夫琅禾费衍射放大衍射图样 总被引:1,自引:0,他引:1
基于球面波夫琅禾费衍射原理 ,通过理论推导得出衍射图样线度与障碍物 (被测物 )到像面的距离z成正比 ,而不是与物镜的焦距 f成正比 .因此仅通过移动障碍物 (改变z)即可使衍射图样线度得到放大 .本文以细丝的衍射实验为例进行了验证 ,实验结果表明该方法是可行的 相似文献
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Yusuf Ziya Umul 《Optics Communications》2011,284(22):5269-5274
The line integral of the boundary diffraction wave theory is derived by considering the exact diffracted fields of a resistive half-plane. The line integral is generalized for arbitrary resistive surface with edge discontinuity. The method is applied to the diffraction problem of waves by a convex resistive spherical reflector and the resultant field expressions are investigated numerically. 相似文献
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The intensity distribution in Fresnel diffraction through a slit includes numerous small fluctuations referred to as ripples. These ripples make the modelling of the intensity distribution complicated. In this study, we examine the characteristics of the Fresnel diffraction intensity distribution to deduce the rule for the peak position and then propose two types of quantum-mathematical models to obtain the distance between the edge and the peak point. The analysis and simulation indicate that the error in the models is below 0.50 μm. The models can also be used to detect the edges of a diffraction object, and we conduct several experiments to measure the slit width. The experimental results reveal that the repetition accuracy of the method can reach 0.23 μm. 相似文献
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球面波入射圆锥透镜产生的出射光束中心光斑直径较小且焦深长,适合通讯领域长距离测量和准直。针对实际操作中球面波光束入射时很可能与圆锥透镜的中心轴线发生偏移或倾斜,使衍射光场发生变化,着重研究圆锥透镜对偏轴球面波光束的衍射模式,并通过衍射理论和稳相法分析,研究其径向衍射光场的分布特性。使用半径为15mm,底角为1°的圆锥透镜进行计算机仿真和实验,最后将实验结果与理论分析和仿真结果相比较,证明球面波的曲率半径和出射光束的传输距离越小,偏轴对衍射模式的影响越小。该研究结果表明:在激光通讯等长距离通信中,使用曲率半径小的球面波光束代替平面波入射圆锥透镜,不仅可以扩展焦深,还可以降低偏轴对测量的影响。 相似文献