Abstract

Confocal reflected light microscopy provides a very high depth resolution if the numerical aperture of the micro-objective is on the order of 1. The most common confocal microscopes rely on scanning the field of view by means of a Nipkow-disc or simply by mechanical scanning the object in a raster scan /l,2,3/. The basic idea of confocal imaging is spatial filtering on the way to and from the object through a small pinhole. This means that only the light from the immediate neighborhood of the image plane is allowed to pass the optical channel which means a very strong suppression of light coming from other than the plane the microscope is focused on. In a reflected light microscope the pinhole of the illuminating light path is imaged sharply onto the surface to be measured and is reflected back and has to pass the same pinhole again. Only if the pinhole is sharp on the surface to be measured the pinhole is imaged on itself and light can get through this pinhole. Unsharp imaging causes the image of the pinhole to be spread out over a considerable area which means that the total light flux is very low.

© 1998 Optical Society of America