Surface Plasmon Fluorescence Microscopy: Characteristics and Application to Bioimaging

Abstract

The imaging characteristics of a widefield surface plasmon fluorescence microscope are studied. It is shown through modeling as well as experiments that the microscope has a donut-shaped point spread function. To mitigate the poor imaging condition arising from this, an optical method of adding conversion elements to the microscope is proposed. The effects of adding conversion elements ? a polarization mode converter or a spiral phase plate, to the detection path of the microscope are explored both theoretically and experimentally. In terms of the frequency domain, it is also shown that the resulting optical transfer functions do not have zero crossings or negative values which contribute to the distortion. This method can also be applied to confocal microscopy to improve its detection efficiency when radially polarized illumination is used, without sacrificing the lateral resolution of the microscope. In addition, a standing wave method is demonstrated to give sub-diffraction limited resolution.