Having been brought up on monocular microscopes I find the omnipresent binocular systems a luxury. To support this viewpoint I'd like to suggest some benefits you may not have considered.

Because I'm used to monocular viewing I sometimes use two different oculars, say 10X and 25X, in order to scan quickly to find an area of interest and then to examine the detail with higher magnification. Occasionally I use both oculars simultaneously and “concentrate” on either image to the exclusion of the other. A better way is to set the interocular distance at the extreme setting most different from your own interocular distance. By moving your head about a centimeter either way you can use either ocular.

This familiar saying may be a little too risque for sober scientists but surely all of us can accept a substitution of the word humor for the word nonsense. For humor is based on a sense of proportion and fitness of relationships, which is the very essence of the scientific obligation to interpret what we observe. In fact, many of our colleagues insert humorous slides in their very serious talks to help wake up the audience and give them an association for remembering a key point. Do we also remember to use this power of humor when teaching, or otherwise communicating with, a lay audience?

Like it or not we are all required to be teachers to our own circle of support people and should furthermore take advantage of any opportunity to educate the world at large about our work. I should like to give a few examples from my own experience in teaching electron optical practice.

The traditional method of preparing high quality projection slides of one's best electron micrographs was to “print” negatives onto Kodak 2″ x 2″ emulsified glass slides using a standard enlarger fitted with a reduction lens and then to tray develop the slide to the desired contrast. As A. Kent Christensen pointed out in the June/July 1994 issue of this publication, the cost of 2″ x 2″ slides has become prohibitive. In any event, I always found adjusting the reduction lens on the enlarger to be a major hassle and searching for the correct exposure and developing times to be a ffustratingly inexact experience with much plate wastage.

Advances in camera technology and digital instrument control have meant that in modern microscopy, the image that was, in the past, typically recorded on a piece of film is now recorded directly into a computer. The transfer of the analog image seen in the microscope to the digitized picture in the computer does not mean, however, that the problems associated with recording images, analyzing them, and preparing them for publication, have all miraculously been solved. The steps involved in the recording of an image to film remain largely intact in the digital world. The image is recorded, prepared for measurement in some way, analyzed, and then prepared for presentation.

Spiderman carefully slid the sample of mud into the microscope. As he increased the magnification he caught sight of a tiny spherical crystal. Zooming in on it, he said “Let's see what it's made of”. He reached over and flipped on the x-ray detector. As the spectrum formed on the screen a gasp went through the small group of researchers. “Kryptonite…the intruder is from another comic strip!”

The primary function of a microscope is to get a closer look at a sample. Many times a closer look is enough. Other times you need as much information as possible to solve a problem. In the above example, a reading of the chemical elements contained in the sample gave important clues about the sample's origin. X-ray analysis in electron microscopy combines elemental analysis with high resolution imaging. Of all the analytical techniques available to microscopists, it is the most highly developed and easiest to use.

If you were to examine surfaces in a typical SEM system using any number of surface analysis techniques, I think you'd be surprised at the results. You might expect to see all materials used to construct the vacuum chamber (e.g., plastic or stainless steel), but frequently the spectra will show mostly carbon, the most frequent culprit of SEM contamination. Carbon is adsorbed onto the walls of the vacuum chamber and builds up on the sample, thereby contaminating the SEM system and compromising image quality. By manufacturing and maintaining a clean SEM environment, this problem can be avoided, and you will increase the overall performance of your SEM system.

The Information Superhighway, Email, The Internet, FTP, BBS, Modems,: all buzz words which are becoming more and more routine in our daily life. Confusing terminology? Hopefully it won't be in a few minutes. All you need is to have a handle on a few basic concepts and terms and you will be on-line with the rest of the “telecommunication experts”. These terms all refer to some type or aspect of tools associated with a range of computer-based communication software and hardware. They are, in fact, far less complex than the instruments we use on a day to day basis as microscopists and microanalysts. The key is for each of us to know what each is and how to make use of the wealth of information which they can make available to us for the asking.

We are all familiar with digital imaging for SEM instruments. Digital Imaging for TEM applications is not as well established. Nevertheless, it seems clear that it will not be long before digital imaging for TEM becomes common place. Systems are improving and costs are plummeting. With this in mind it is timely to review what digital imaging for TEM involves.

In normal TEM operation an electron bream is scattered through a thin section of a sample. Physical mechanisms cause the electrons of the beam to scatter, producing bright-field images, dark-field images and diffraction patterns. The operator adjusts the instrument to display one of these images on the instrument's viewing screen. A photographic record is collected by flipping the viewing screen and exposing a sheet of film held in the TEM's camera. Exposed negatives can be removed for developing and printing in batches, using standard darkroom techniques.

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 X 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 X 4096 resolution or greater.

One of Olympus' not well known product in the American market is the UH3 Scanning Acoustic Microscope (SAM). This state of the art, highly versatile microscope has many applications from non-destructive imaging to biomedical analysis, to pharmaceutical applications to name a few areas of current industrial interest.

The principle behind SAM is quite simple, and uses the basic physical laws of reflection. High frequency sound waves are mechanically produced by a piezoelectric crystal. A high voltage impulse spike starts the crystal vibrating at its preset resonant frequency emitting acoustical plane waves through a medium with a relatively high sound velocity such as sapphire. The waves are made to converge by a half-spherical lens at the bottom of the sapphire rod. The diameter of the lens is less than one millimeter and depends on the operating frequency. The lower the frequency, the larger is the diameter of the lens.

Successful immunolabeling in electron microscopy of animal and plant tissues requires a combination of excellent antigen preservation while maintaining the original structure of the tissue. One important element is tissue embedding which accomplishes two goals for the immunohistochemist, the preservation of tissue specimen structure and maintenance of biological antigenicity. Tissue embedding in plastic resins is a common method in which several important elements must be considered.

1. 1. Fine tissue structure must not be damaged by the polymerization.

2. 2. The plastic must be stable to the electron beam.

3. 3. Light scattering properties of the plastic should be minimal.

4. 4. The plastic should cut easily.

5. 5. The plastic must be of sufficiently low viscosity to infiltrate the tissue.

Historically, microscopes have been used to gather morphologic data. We have called people who use these instruments microscopists, and it is implied that microscopists are morphologists. As was pointed out in the April/May issue of this newsletter, useful information about a specimen is also gained from temporal analysis. Further, it has been appreciated that the new family of scanning probe microscopes can be used to gather additional types of information so that these instruments have the potential to be useful beyond the dreams of a conventional microscopist. As we will discuss in this article, the future is here for one such application.

The atomic force microscope (AFM) takes advantage of the leverage afforded by the deflection of a laser beam bounced off a cantilevered stylus that is scanned over the surface of a specimen.