Lateral resolution enhancement in confocal microscopy by vectorial aperture engineering

This article reports the design and implementation of a lateral resolution-enhancement technique in confocal microscopy that can work, in principle, either in the reflection mode or in the fluorescence mode. Taking the difference between two images corresponding to two different vectorially (involving amplitude, phase, and polarization of light) engineered illumination pupils or apertures of a confocal microscope, high spatial frequency contents in the resultant image can be significantly enhanced. This can be realized by incorporating an extra vectorial beam-forming element into the illumination beam path of a conventional confocal microscope. The method of the proposed technique has been explained by giving it an analytical treatment supported by numerical simulation results. The technique has been implemented in a reflection mode confocal microscope and results obtained are presented.