Tunable optical sectioning in confocal microscopy by use of symmetrical defocusing and apodization

We present two novel optical methods to achieve a significative improvement in the optical-sectioning capacity of confocal scanning microscopes. The techniques, whose real power is the simplicity with which they can be implemented, consist of a suitable combination of symmetrical defocusing with two different manners of apodizing both parts of the confocal architecture. It is shown that the proposed techniques are useful in both the bright-field and the fluorescence modes and for reflection and transmission geometries.