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©1990-2002 J.Paul Robinson, Purdue University
Depth of Field and Resolution
•Depth of field is designated as the longitudinal distance for the formation of a sharp image is obtained at a fixed point in the image plane
•Limits of resolution are diffraction limited - the diffraction image is a point is a bright central spot surrounded by what is called the Airy disk (alternating light and dark rings)
•at wavelength l, the
radius of the Airy disk is 0.61 l Thus
to resolve two points they need to be at least this distance apart (radius of the Airy disk) thus the resolution is defined as 0.61 l /NA
Shapiro p 97
