Fibered interference Scanning Optical Microscopy for living cell imaging

We present imaging of biological cells by a fibered high-resolution optical microscope, which we call interferometric Scanning Optical Microscope (iSOM). The topography and surface structure of mouse fibroblasts and living hippocampal neurons are clearly revealed by iSOM. Its working principle is based on the interference of the internally reflected light at an optical fiber tip with the light reflected by the surface facing the tip. iSOM is working in the optical far field, i.e. at tip-sample distances of the order of a few microns, thus avoiding any mechanical contact with the sample. This feature is of particular importance for the observation of living cells. Samples with topography in the micron range can thus be imaged at high resolution without any closed-loop tracking of the fiber tip height as done in AFM or NSOM. This feature allows to use less complex electronic control units and much faster recording speeds. In addition, iSOM can be developed at reduced costs and is well suited for integration with other measurement techniques, as only an optical fiber has to be positioned near the sample surface.