A marriage of microscopy and image compression

Instead of looking at a surface pixel by pixel, a new microscope takes a more global view to achieve improved resolution. The detailed chemical structure of a surface can reveal a wealth of information about such processes as catalysis, corrosion, and wetting. One technique for getting at that surface structure is sum frequency generation (SFG), in which a pair of photons simultaneously strike a spot on the surface, interact with the material there, and convert to a single photon. Conventional SFG microscopes use a raster-scan; that is, they image the surface one pixel at a time. That approach has an inherent limitation: As the microscope samples smaller pixels to improve resolution, the intensity associated with each pixel drops, eventually becoming too small to measure. Now Steven Baldelli of the University of Houston, Kevin Kelly of Rice University, and colleagues have combined the mathematics of image compression with SFG to create...