Abstract

This incident-light microscope employs an oscillating three-facet mirror to scan the image of an illuminated slit across the object plane. The light returning from this illuminated region is passed through a second slit located in the imaging system. As a result nearly all the light reaching the image plane is from a thin layer centered at the object plane. By adjusting the slit widths the optimum optical section thickness can be chosen for the particular specimen and the light source used. For studies of the inner ear of the cat, an optical section thickness of 300 μm (full width at 1/10 power) or less is chosen, so that reflections or scattering from the round window membrane are eliminated. This permits identification of anatomical details on the basilar membrane without opening the round window membrane and disturbing the environment of the structures of interest. Results of theoretical calculations of optical section thickness are given, showing how it can be varied by selection of numerical aperture of the objective and slit width.

© 1987 Optical Society of America