The Influence of the Condenser on Microscopic Resolution

Abstract

An expression is found for the distribution of light in the image of two small apertures which are illuminated by a condenser of numerical aperture equal to s times that of the imaging objective. The resolving power of the system is written ρ=Kλ/(N.A.), and K is found as a function of s. It is shown that precisely the same result obtains for both critical and Kohler illumination.