Effect of half-stop lateral misalignment on imaging of dark-field and stereoscopic confocal microscopes

There are several ways to realize dark-field imaging in confocal microscopy. In a recent paper [J. Microsc. 181 260-268 (1996)] we suggested a simple modification of a commercial confocal microscope to incorporate dark-field imaging. This modification involved an aperture stop covering half of the entrance pupil of the objective lens. Now we investigate the lateral misalignment of the aperture stop for dark-field and stereoscopic confocal microscopes. We show the effect of lateral alignment of the half-stop on the point-spread and transfer functions and also examine the detected signal from a sloping plane reflector. Lateral and axial resolution values are given from theoretical data.