Fraunhofer Diffraction Geometry
夫琅禾费衍射几何
 Although the formal Fraunhofer diffraction requirement is that of an infinite screen distance, usually reasonable diffraction results are obtained if the screen distance D >> a. But an additional requirement is D>> a2/λ which arises from the Rayleigh criterion as applied to a single slit. If the conditions for Fraunhofer diffraction are not met, it is necessary to use the Fresnel diffraction approach. The diffraction pattern at the right is taken with a helium-neon laser and a narrow single slit. The pattern below was made with a green laser pointer. 右侧的衍射图样使用氦氖激光和一个窄单缝拍摄而成。下方的图样则使用绿色激光笔制作。
尽管夫琅禾费衍射的正式要求是屏幕距离为无限远，但通常在屏幕距离D >> a时即可获得合理的结果。此外，根据单缝的瑞利准则，还要求D >> a²/λ。如果无法满足夫琅禾费衍射的条件，则必须采用菲涅耳衍射方法。 |
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Note: To obtain the expression for the displacement y above, the small angle approximation was used.
注意：为了得到上述位移y的表达式，采用了小角度近似。
单缝衍射计算 |
单缝强度 |
双缝干涉 |
与双缝实验的比较 |
|
考察近似 |
缝宽变化 |
Diffraction concepts
Fraunhofer diffraction
Oxford Optics
索引 夫琅禾费衍射 哥伦比亚大学光学
| HyperPhysics***** Light and Vision
HyperPhysics ***** 光与视觉 | R Nave |
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