Subtle changes in existing microscope technology can enhance our ability to explore features and characteristics of components and materials. For example, researchers at Los Alamos National Laboratory have rethought confocal microscope design, creating an instrument that is small enough and inexpensive enough to make confocal imaging available as an inexpensive attachment for an ordinary-light microscope. Another NIST research team has added accurate mapping of microscopic magnetic fields to the atomic force microscopy repertoire. A Virtual Confocal Microscope Confocal microscopes have become popular over the past decade or so because they offer imaging capabilities superior to those provided by conventional-light microscopes. These superior capabilities include better contrast and resolution and the ability to resolve images in three dimensions.
Confocal microscopes tend to be large, expensive, and relatively slow to produce an image.
Selected Rays Figure 1 shows the arrangement of optics for one conventional type of confocal reflectance microscope. The illumination starts with a beam of light that falls on a pinhole aperture at the microscope's focal plane. The objective focuses the small amount of light that passes through the aperture onto the sample, which absorbs, scatters, and reflects light according to its optical properties. A portion of the light scattered or reflected from the sample returns through the objective's aperture and gets focused back onto the pinhole. Only those rays that originate at the location of the objective's focal point find their way back through the pinhole.