d) Light from a monochromatic point source of wavelength 2. is focused to a point image by a Fresnel zone plate having 1
Posted: Thu Feb 17, 2022 11:09 am
d) Light from a monochromatic point source of wavelength 2. is focused to a point image by a Fresnel zone plate having 100 open odd-half-period zones with all even zones opaque. Compare the intensity of the point image: i) when the zone plate is removed [3 marks ii) when the zone plate is replaced by a lens of the same focal length and diameter. [3 marks) Assume the diameter of the opening is small compared to the distance from the source to the image.