The living human eye is in constant motion. The cornea, which is the transparent front surface of the eyeball, is a formidable specimen for microscopy. How can we use a microscope to obtain sufficient contrast in order to observe cellular and subcellular details on a moving, transparent specimen? Although the normal human cornea is free of blood vessels, there are many nerves within the 500 μm thickness of this tissue. How can we observe these nerves in the living human eye?

To accomplish these aims, use a new real-time, scanning slit confocal microscope that was developed by Dr. A. Thaer for imaging the in vivo human cornea. The optical design of the real-time, scanning slit confocal microscope is shown as follows in Figure 1. The confocal microscope is a modification of the real-time, scanning slit confocal microscope based on an oscillating too-sided mirror (bi-lateral scanning) which was designed and first constructed in 1969 by G. M. Svishchev in Lenningrad.

In October 1979, a technician in the electron microscopy laboratory of one of the teaching hospitals in Toronto spilled a bottle containing approximately 500 ml of 2% osmium tetroxide. He asked for help, and four other technicians were involved in the cleanup. They all were exposed to osmium tetroxide vapours for long enough to show signs of acute intoxication. They developed redness and swelling of the conjunctiva, impaired vision, chest pains, breathing difficulties and skin irritation and were taken into Emergency Care at the hospital. The occular symptoms disappeared after two days, but the chest pains and breathing difficulty persisted for approximately one week.

This accident could have had more serious consequences. It has been reported that exposure to osrruum vapour could lead to blindness and serious respiratory trouble. At McMaster University Medical Centre, the safety committee gives precise procedures to be followed in case of accidents with dangerous chemicals. All the occupants of the laboratory have to leave immediately and phone the safety and security team.

Microscopes are being used to obtain more and more information from a specimen. We are all acquainted with various ways to visualize structures, whether on the surface or embedded within a relatively translucent specimen. There are many ways to “tag” a molecule of interest so that the molecule can be positively identified within the specimen. Traditional microscopes are not able to identify a molecule for us. Other analytical tools are used for that. For example, the nuclear magnetic resonance (NMR) spectrum of a molecular species yields a “fingerprint” that gives a reliable identification. Wouldn't it be great to combine the sensitivity of a state-of-the-art microscope with the molecular analytical capabilities of NMR?

Well you guessed it, this has been done. This approach was first suggested by John A. Sidles at the University of Washington and has recently been demonstrated by Dan Rugar and colleagues at the IBM Almaden Research Center in San Jose.

The history of microscopy has focused on better and better resolution, as has been documented on these pages [e.g., J.-P Revel). As one can see in the first graph, the early improvement in resolution was agonizingly slow, as it was dependent on technological improvements in optics and methods for preparing specimens. Hans and Zacharias Jensenn are credited with being the first to put two lenses in the same optical path to create a primitive microscope in 1590 Nearly a century later Antoni van Leeuwenhoek was impaling specimens an needles. Whereas van Leeuwenhoek and other observers were able to make significant observations to change fundamental concepts of their day, microscopists such as Ernst Abbe, Hermann Ludwig Ferdinand von Helmholtz, Lord John Rayleigh and Carl Zeiss brougnt us to the brink of optimal performance of the light microscope.

The Gopher, although as industrious as the Beaver and the skilled architect of complex subterranean mazes which should inspire as much awe as the dams and lodges built by beavers, is rarely revered as the mascot of Institutes of Higher Education. In real life many, my wife and I included, relentlessly pursue the garden variety gopher who dares to intrude and destroy prized plants, or for that matter even plants we do not care about. It is my job to deal with them and I do it like a Daemon that's BinHex-ed. However there is a highly prized and very beneficial, if virtual, species of GOPHERS. These creatures, created at the U. of Minnesota (home of the Golden Gophers), put their tunneling ability to good use, digging out otherwise hard to find information and so performing great services on the latter day wonder of electronic communication, the Information Superhighway, the Internet.

Like many other people I find myself not having the time to do all the things that I would like to do in a day. I have always wished I could emulate the young lady in Prof. Arthur Bullers (1874-1944) limerick which was published in the December 19,1933 issue of that reputed journal, Punch:

Well, up to now I have not succeeded in my attempts to gain time in this way, but there is hope, there is hope as I will try to make clear in a minute.

First of course, as we all know, the speed of light is finite. This was first demonstrated by Roemer in 1676, He measured the interval between successive eclipses of the intermost satellite of Jupiter (that would be lo, with its sulfur spewing volcanoes), at a time when Jupiter was close to Earth.

I am a professor at a university, and like most of my colleagues I divide my time between teaching, administration, service work and basic research. Of all these activities it is the research that I and my students have dene that has been most important for the advancement of our respective careers. Research is indeed the life blood of science and the meeting of MSA in New Orleans this month, will be an occasion to celebrate this and to show each other what we have been doing since we saw each other in Cincinnati last year.

I am driven to write this column because some nights ago I watched a program on the problems surrounding the delivery of the impending “universal” health care package. On the stage were Senators Dole and Mitchell, along with people representing different opinions about the issues at hand.

As is the case with many other aspects of our lives here in the twilight years of the twentieth century, the computer is having an evermore pervasive role in the daily endeavors of the electron microscopist. And as I contemplate the little button on the microwave that allows me to burn popcorn the exact same way, time after time, I am led to wonder “where is it all going?”…the technology that is. I know where the burnt popcorn will end up. Whether we like it or not, the computer is a tool that can drastically improve our productivity, and typically such productivity gains occur precisely within those tasks where mistakes are the most likely to creep in, to wit: the mundane and repetitive.

As an example, consider the task of indexing a diffraction pattern for a known crystal. In the far distant and superstitious past of the mid to late 1960's, this task required all sorts of strange alchemy.

Prior to Near-Field Scanning Optical Microscopy (NSOM) there were two major light microscopy techniques; optical and confocal.

In an optical microscope a sample is illuminated with a flood of light. The lighted area is then imaged and magnified by collecting the light that is either reflected from or transmitted through the sample by a series of glass lenses. A color magnified image of the sample may be seen directly or displayed on a TV screen. Even if the lenses could be made perfectly, the resolution and magnification of an optical microscope are limited by diffraction effects to approximately one half of the wavelength of the light that is used. Optical microscopes are used routinely to image the general shape of samples as small as human chromosomes or compact disk bits.

In recent years, microscopy systems have become more capable of capturing, transferring, and manipulating electronic images. In the last issue of this publication, there was a summary of different image format types and their flexibility for use with microscopy. This article will briefly discuss converting images among different formats, which often becomes necessary when transferring images from one software application to another or creating hardcopy of the image. In order to transfer the image, either the original software has to save the image to a format which the new software or output device can read, or that new software or device has to read a format which is native to the image generating software.

Sometimes (happy days), this all works out straightforwardly. Other times, transferring an image is impossible. The user then has the choice of writing his own conversion software, finding freeware, or purchasing a commercial conversion utility.

When one speaks of microscopes one usually imagines devices which produce spatially resolved images. So it is most intriguing when a novel application of microscopic techniques permits discoveries not by forming images but by allowing very precise measurements to be made on very small objects. The blind showing the way to the sighted! A recent paper in Nature is a good example of what I speak. It deals with biological motors, which, as cell biologists are learning, are involved in the movement of cells and the movements of organelles within cells. There are a number of different biological motors, but all are molecules which change shape, as they convert the chemical energy derived from the hydrolysis of high energy molecules such as ATP, into mechanical work. As the motor molecules undergo this conformational change and then return to their original state they take a step away from their starting point, dragging along the structures to which they are attached.

The electron source is the most important component of the Scanning Electron Microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in a SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required, e.g. a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp. to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.