Scanning photon microscopy

We describe the scanning photon microscopy (SPM), a new method of microscopic image formation that is analogous to the scanning electron microscopy but carried out entirely by optical means and therefore is without the cumbersome sample preparation procedures. A laser beam is focused and raster-scanned over the surface of an object by means of an a motorized micrometer. The light reflected from the object surface is collected by a detector that is placed at a finite angle with respect to the incident beam. The geometry of the system is such that it yields images reminiscent of the scanning electron microscopy with striking three-dimensional impression and the effects of shadowing and diffuse reflection. In the preliminary experiments several artificial and biological objects are imaged using this technique obtaining images with about 5 micron resolution and reasonable image quality. Because this is a scanned optical system, the optical quality requirement is significantly relaxed in comparison to conventional wide-field imaging system. We also consider the possibility of surpassing the wide-field system in terms of the resolution and depth of focus by use of Bessel optics. The simple concept can be extended in many directions such as fluorescence and nonlinear optical imaging.