Using offset interfering beams for improved resolution in confocal imaging: The potential of the PSAF-technique

The interferometric spatial overlap of two laterally offset focal field distributions of a high numerical aperture lens in combination with confocal detection lead to improved resolution in confocal imaging. Experimental data of the achieved signal, the point spread autocorrelation function (PSAF), are presented for both the lateral and axial directions. Numerical simulations of lateral PSAF imaging of selected fluorescent objects show an increased resolution of up to 30% with moderate ringing, obtainable also in the presence of moderate spherical aberrations.