Previous papers about coherent scanning optical microscopes took into account two types of microscope: those with a point detector called type-II or confocal microscopes and those with an infinitely large area detector called type-I or conventional microscopes. Here the pinhole size of a type-II microscope was permitted to vary, and it is shown how the size could affect the imaging properties of a real microscope. The three-dimensional optical transfer function is established, and we discuss in particular the resolution capabilities, lateral as well as longitudinal, of a scanning microscope with a given pinhole size or detector area. Finally, a rigorous confocality criterion, which will answer the question of how small the pinhole should be made to give confocal imaging properties to a scanning microscope, is given.
“Dependence of two- and three-dimensional optical transfer functions on pinhole radius in a coherent confocal microscope“, Valter DRAZIC, Journal of the Optical Society of America A, Vol. 9, No 5, May 1992, 725-731
“Dependence of two- and three-dimensional optical transfer functions on pinhole radius in a coherent confocal microscope – comments“, C. J. R. Sheppard, Min Gu, Journal of the Optical Society of America A, Vol. 10, No 3, March 1993, 533-534
“Dependence of two- and three-dimensional optical transfer functions on pinhole radius in a coherent confocal microscope – reply to comments“, Valter DRAZIC, Journal of the Optical Society of America A, Vol. 10, No 3, March 1993, 535-537