Interferometric resolution improvement for confocal microscopes.

We present a method for increasing the lateral resolution and detection efficiency of scanning fluorescence microscopes by adding an interferometer with partial image inversion to the detection pathway. We show that the resulting detection transfer function is essentially the absolute square of the system's amplitude transfer function enlarged to twice its spatial frequency range. Simulations for a confocal system yield a lateral FWHM resolution of 168 nm (135 nm after image subtraction) as compared to 218 nm for confocal detection without an interferometer. Furthermore we demonstrate how this method is suitable for extended focus imaging. Here simulations for Bessel beam excitation and interferometric detection yield a resolution of 146 nm (116 nm after image subtraction) as compared to 199 nm for integrating detection without an interferometer.