光阑对平面光波傍轴性的影响
Effect of apertures on paraxiality of plane wave
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摘要: 根据单色光傍轴度的定义，分别研究了圆形光阑和方形光阑对平面光波傍轴性的影响。推导出平面光波经圆形光阑和方形光阑衍射后其傍轴度的解析表达式。平面光波经圆形光阑或方形光阑衍射后，其傍轴性下降，傍轴度小于1，傍轴度下降量取决于光阑尺寸与入射平面光波波长的比值。数值计算结果表明：随光阑尺寸与入射平面光波波长的比值从零开始增大，平面衍射光波的傍轴度从零开始快速增大而后趋于一饱和值，但光阑的形状不影响平面衍射光波的傍轴性。Abstract: According to definition of degree of paraxiality for a monochromatic light beam, the effects of a circular aperture and a rectangular aperture on the paraxiality of a plane wave have been investigated, respectively. Analytical expressions of degree of paraxiality for a plane wave diffracted by a circular aperture and a rectangular aperture have been derived. If a plane wave is diffracted by a circular aperture or a rectangular aperture, the corresponding paraxiality decreases, which means that degree of paraxiality of the diffracted plane wave is smaller than one. Decreasing quantity of degree of paraxiality is determined by the ratio of aperture dimension to incident wavelength. The numerical results show that degree of paraxiality of the diffracted plane wave quickly augments from zero a
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Key words:
- plane wave /
- paraxiality /
- aperture /
- diffraction
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