Since 1996 the Minnesota Microscopy Society (MMS) has had several different opportunities to use the “Microscopic Explorations” [1] handbook that has been developed by MSA in collaboration with the Lawrence Hall of Science [2] as part of their Great Explorations in Math and Science (GEMS) series. Initially we used a beta-test version of the manual and worked with several different schools in the St. Paul's school district. Since then we have broadened the range of our outreach, and have interacted with different school districts, as well as local museums and other youth and community organizations - including church youth groups, scout groups and local governments. One of the strengths of the manual is that it can be used in many ways, and is adaptable to the particular learning situation available. These opportunities can span the range from essentially uncontrolled interactibns with the general public, with its large age range and ability spectrum, to the very carefully structured setting of an ongoing, single-age class program.

Of all the meanings and definitions of the word passion, the two that are applied here are “a pursuit to which one is devoted” and “excitement of the mind.” These are the emotional feelings that drive artists, musicians, writers, and scientists to fervently apply their skills. Within the field of microscopy, scientists and technologists display their zeal when they pursue the development of new techniques and methodologies, when they invite the world into their laboratories through telepresence microscopy, and when they use only the highest of standards to execute their studies. It is the ardor that drives retired microscopists to deliver microscopes to school children, and the joy that makes teachers of us all, as we are so desirous to share our knowledge. Passion is the deep feeling that can motivate a microscopist to produce imaginative IMAX movies and films for public television series.

During the last five years we have all seen and experienced how the explosive growth of the Internet has impacted our lives and our technology. At the 1995, 1996 and 1998 Microscopy and Microanalysis meetings, sessions devoted to technologies for remote access; control and collaboration were held. In each of these, a number of authors outlined the various methods by which they had implemented their concept remote access. In this tutorial we will look at where each of the technologies described during those years currently stands from the point of view of simplicity, effectiveness, cost and overall versatility.

From the onset, it should be recognized that there is no single, universal solution to the task of implementing any telepresence collaboration technology over the Internet. Each solution has both its merits and its disadvantages. However all interactions require the collaboratory to address a universal set of functional requirements they are:

Multi-photon excitation microscopy provides attractive advantages over confocal microscopy for three-dimensionalry resolved fluorescence imaging and photochemistry. The most commonly used type of multi-photon excitation is two-photon excitation where simultaneous absorption of two photons leads to a single quantitized event. The powerful advantages of using two-photon excitation microscopy arise from the basic physical principle that the absorption depends on the square of the excitation intensity. In practice, two-photon excitation is generated by focusing a single pulsed laser through the microscope. As the laser beam is focused, the photons become more crowded, but the only place at which they are crowded enough to generate an appreciable amount of two-photon excitation is at the focus. Above and below the focus, the photon density is not high enough for two of them to interact with a single fluorophore at the same time. This dramatic difference between confocal and two-photon excitation microscopy is shown in Fig. 1.

Electron microscopy (EM) has become an increasingly powerful method for the determination of three-dimensional (3D) structures of proteins and macromolecular complexes. EM offers advantages over X-ray crystallography and NMR for obtaining structural information about proteins in physiological conditions, as components of large assemblies, that cannot be obtained in large quantity, or that fail to yield 3D crystals. EM has been used to obtain structural data from images of isolated molecules and molecular complexes, two-dimensional (2D) protein crystals, and helical protein arrays. Helically arranged proteins allow the most rapid determination of 3D maps because they contain a complete range of equally spaced molecular views, therefore no tilting of the sample with respect to the electron beam is required. However, so far 3D structure determination of helical assemblies has been limited to proteins that naturally adopt this organization and to proteins that fortuitously crystallize as helices.

Single particle processing is a technique for determining the 3D structure of molecules and macromolecular assemblies using TEM images of individual molecules. In principle, individual molecules float freely in solution before freezing/fixation, so particles in the micrographs represent 2D projections of individual molecules in random, or nearly random orientations. Practically speaking, surface effects often cause preferred orientations to exist in the particle population. In addition, single particle processing makes the assumption that all of the individual molecules are either in the same conformation, or in a discrete mixture of conformations. Single particle processing refers to the computational techniques by which thousands of individual molecule images are processed to produce a 3D structure. The technology of single particle processing has advanced to the point that a low resolution reconstruction (∼ 15-25 Å) can be performed on a cooperative specimen quite rapidly, typically less than a month from purified specimen to 3D model.

Over the several years that imaging energy filters have been available commercially, numerous and wide-ranging applications have demonstrated elemental mapping with a resolution approaching 1 nm. A few reports have even shown resolutions <0.4 nm. Elemental mapping by energy-filtered transmission electron microscopy (EFTEM) is clearly an attractive and powerful tool, but some aspects of the techniques can be complex, with many pitfalls awaiting the unwary. This tutorial aims to cover some practical aspects of elemental mapping by EFTEM. It is based largely on the author's work at the ORNL SHaRE User Facility, where EFTEM research has been performed since 1994 with a Gatan imaging filter (GIF) interfaced to a Philips CM30T operated at 300 kV with a LaBa cathode.120 Most of the applications have been to metals and ceramics, emphasizing interfacial segregation and precipitation.

For quantitative composition mapping by EFTEM a number of interrelated parameters [field of view, resolution (δ),

Atom probe tomography (APT) is an ultrahigh resolution microanalytical technique that enables the spatial coordinates and elemental identities of the atoms in a small volume of material to be determined. The specimen volume that may be analyzed is typically ∼ 10 to 20 nm square by ∼ 100 to 250 nm deep, and contains up to ∼ 1 million atoms. The distribution of the solute atoms within this volume may then be reconstructed from these data. The compositions of small volumes are determined by simply counting the number of atoms of each type within that volume, and thus the technique provides a fundamental measure of local concentrations. Atom probe tomography requires that the specimen has some electrical conductivity and may be applied to almost all metals and alloys, many semiconductors, and some electrically conducting ceramics. The sharp needle-shaped specimens may be fabricated from bulk and thin film materials with the use of electropolishing, chemical or ion milling methods.

Two of the most significant microscopy milestones that were achieved in the last century were the imaging of individual atoms and the identification of individual atoms. Both these remarkable achievements were due to Prof. E. W. Miiller and members of his group at Pennsylvania State University. Almost fifty years ago, Miiller introduced a new type of microscope in which a sharp needle-shaped specimen was pointed at a fluorescent screen, Fig. 1. By applying an appropriately high positive voltage to the specimen, image gas atoms near the apex of the specimen could be ionized and radially projected towards the screen where they produced highly magnified images of the specimen surface, Fig. 2. By cryogenically cooling the specimen and using helium as the image gas, the first images of individual atoms were obtained in a field ion microscope by Bahadur and Müller on October 11th, 1955.

Transmission electron microscopy to a resolution of 0.89Å has been achieved at the National Center for Electron Microscopy and is available to electron microscopists who have a requirement for this level of resolution. Development of this capability commenced in 1993, when the National Center for Electron Microscopy agreed to fund a proposal for a unique facility, a one- Ångstrom microscope (OÅM).2 The OÅM project provides materials scientists with transmission electron microscopy at a resolution better than one Angstrom by exploiting the significantly higher information limit of a FEG-TEM over its Scherzer resolution limit. To turn the misphased information beyond the Scherzer limit into useful resolution, the OÅM requires extensive image reconstruction. One method chosen was reconstruction from off-axis holograms; another was reconstruction from focal series of underfocused images. The OÅM is then properly a combination of a FEG-TEM (a CM300FEG-UT) together with computer software able to generate sub-Ångstrom images from experimental images obtained on the FEG-TEM.

Before the advent of the OÅM, NCEM microscopists relied on image simulation to obtain structural information beyond the TEM resolution limit.