Application of Structured Illumination in Nano-Scale Vision

Abstract

We describe how structured illumination patterns can be used to increase the resolution of an imaging system for optical microscopy. A target is illuminated by a sequence of finely textured light patterns formed by the interference of multiple coherent beams. The sequence of brightness values reported from a single pixel of a CCD imager encodes the target contrast pattern with sub-pixel resolution. Fourier domain components at spatial frequencies contained in the probing illumination patterns can be recovered from the pixel brightness sequence by solving a set of over-determined linear equations. We show that uniform angular spacing of the beams generating the illumination patterns leads to less than ideal sampling of the transform space and we propose alternative geometric arrangements. We describe an image reconstruction algorithm based on the Voronoi diagram that applies when the transform domain is not sampled uniformly. Finally, the contrast patterns within individual pixels can be spliced together to forman image encompassing multiple pixels.