Some Experimental Measurements of Diffraction Images in Low-Resolution Microscopy

Experiments are described in which the sharply focused diffraction images of circular holes in a thin, opaque screen were measured using an objective of low numerical aperture (n.a.=0.120) and light of wavelength λ=5300 Å, the condenser aperture equalling that of the objective. Further results are given showing the effect of variations in the condenser aperture upon the image of a thin, opaque straight edge. The results are compared with the predictions of scalar theory, the agreement being generally within the limits of experimental error.