Confocal scanning optical microscope with circular scan line

A reflected-light confocal scanning optical microscope with circular scan line is described. For the horizontal scanning, the instrument uses a rotating dispersive prism embedded at the tip of a hollow motor shaft. The rotating hollow motor shaft accepts a polarized collimated laser beam and transforms it into a rotating beam, with a cone-shaped trajectory, on its exit from the prism. The rotating beam then passes through an inverted telescope and a quarter-wave plate before it is focused onto the specimen plane by a conventional microscope objective. To improve upon the ranging accuracy, a telecentric scan is maintained throughout the scan. The reflected light travels back through the same components until it is redirected by a beam splitter to pass through an analyzer and a pinhole before arriving at the detector. The use of the same optics for both illumination and imaging automatically satisfies the confocal requirement, and eliminates the need for a synchronizing mechanism. Also, the use of a rotating prism renders the system completely insensitive (for all practical purposes) to motor wobble.