Question

Derive the expression for fical lenght of a zone plate

Answer 1

Answer:

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Explanation:

rn = root n lambda f. A zone plate is a device used to focus light or other things exhibiting wave character. Unlike lenses or curved mirrors however, zone plates use diffraction instead of refraction or reflection. Based on analysis by Augustin-Jean Fresnel, they are sometimes called Fresnel zone platesin his honor.