Tables are presented giving the MTF of an aberrationless defocused lens with circular aperture for objects illuminated with incoherent monochromatic light. MTF values are given to six decimal places for reduced spatial frequencies νr = 0(0.01)1 and defocusing Δ = 0(0.1)0.4, 0.5(0.5)5, 10(5)50, except that 5/Δ is an upper limit on νr. Here Δ is measured in units of Rayleigh’s ¼ λ tolerance on defocusing. The integral of the MTF and (MTF)2 are also given for Δ ≤ 5. The numerical integration was performed by Simpson’s rule over most of the range and by series expansion over the rest. An error analysis is appended. Tables of the line spread function for the focused case are also given.
Leo Levi and Richard H. Austing, "Tables of the Modulation Transfer Function of a Defocused Perfect Lens," Appl. Opt. 7, 967-974 (1968)