We give a simple proof of the image sharpness criterion S<sup>1</sup> introduced by Muller and Buffington. A close connection with interferometric techniques for diffraction-limited imaging is pointed out. The method of our proof provides indications on the limited validity of several other sharpness criteria.
© 1977 Optical Society of America
J. P. Hamaker, J. D. O’Sullivan, and J. E. Noordam, "Image sharpness, Fourier optics, and redundant-spacing interferometry," J. Opt. Soc. Am. 67, 1122-1123 (1977)