One of the most pervasive problems in microscopy is that of making sure that what one is observing represents reality. The complex specimen preparation steps which have to be followed to obtainimages of biological samples all produce artifacts, at least in the sense that they modify the sample. The investigator has to somehow show that these changes in the sample reveal true microscopic features, rather than structures which do not exist in the living. This, of course, is why polarized light microscopy, phase and interference microscopy and their derived approaches, all of which reveal detail in live untreated specimen, are so important, in spite of the limited resolution which can be achieved.

When electron microscopy was in its infancy there were, and justifiably so, even more severe fears about the reality of what could be seen. Even visionary people like Gabor had their doubts and the first steps in biological microscopy were taken with the realization that if the sample was burned to a crisp, perhaps examination of its cinders would still give valuable information.

In his preface to the first edition of The Particle Atlas, Jim Lodge talks of the challenge he posed to Dr. Walter McCrone in the 1950s to come up with a taxonomy for particles to assist in the identification of particles under the microscope. Jim's interest and the support of the Midwest Air Pollution Prevention Association and, laier, the US Public Health Service, gave birth to the first edition of The Particle Ailas. This first edition, published in 1967, was a single volume which combined guidance on particle separation and identification techniques with a collection of optical micrographs of reference particles. The demand for this reference work soon outpaced the supply. In the meantime, however, it had become obvious that reprinting was not the answer as increased application of the microscope, in all its implementations, to environmental pollution and industrial contamination had resulted in a need for a more comprehensive work.

Although it has been possible for many years to determine the average position of atoms by using diffraction techniques, finding the positions of specific atoms has been an elusive target. This latter goal is now in sight. Individual atoms on surfaces were first seen in the seventies by the Chicago Group using the then newly invented Scanning Transmission Electron Microscope (STEM). More recently atoms on surfaces have also been seen by Scanning Tunneling Microscopy (STM) and associated variants (e.g. Atomic Force Microscopy). Atomic structures in the interior of a material have been imaged in recent years through atomic resolution transmission electron microscopy of thin film specimens. Progress in these developments is following an acceleration path and the Materials Research Division of the NSF recently commissioned a panel to review the area and provide advice on an appropriate response.