Confocal supercritical angle microscopy for cell membrane imaging

We demonstrate subwavelength sectioning on biological samples with a conventional confocal microscope. This optical sectioning is achieved by the phenomenon of supercritical angle fluorescence, wherein only a fluorophore next to the interface of a refractive index discontinuity can emit propagating components of radiation into the so-called forbidden angles. The simplicity of this technique allows it to be integrated with a high numerical aperture confocal scanning microscope by only a simple modification on the detection channel. Confocal-supercritical angular fluorescence microscopy would be a powerful tool to achieve high-resolution surface imaging, especially for membrane imaging in biological samples. (C) 2014 Optical Society of America