My 9 years in industry, 5 years in academia, and 4 years as a postdoc tell me this about getting a regular (tenure-track) faculty appointment:

On a very simple level, one who wishes to be in lofty pursuits (an academic position at a research institution, where the goals are noble and the intellectual rewards are pure and at least some people respect you) would follow this conventional-wisdom paradigm:

First get a Ph.D (or MD/Ph.D), next get a postdoc, and then get an assistant “prof.” position.

The cutting-edge tool for IC fab support and defect review brings together the Focused Ion Beam (FIB) technology with the Scanning Electron Microscope (SEM) into a single workstation. The twin beam FIB/SEM workstation, FEI Company's DualBeam™ 820 for example, combines the unique micromachining, microdeposition, and analysis capabilities of a FIB with the high resolution imaging power of a Schottky field emission scanning electron microscope (FE SEM). The full functionality of both instruments is available and neither is compromised by the other.

The world of electron microscopy is in a period of transition from acquiring images on film to acquiring images digitally, using CCD cameras, for example. It would be useful to know how much information there is on a piece of film, in order to know how film compares with digital methods and to be able to make good judgements on the optimum moment to change from one technology to the other.

This is an attempt to use simple arguments to estimate just how much information there is in an image exposed on film in the transmission electron microscope. The main reason for addressing this issue is that, while many people are affected by it, there seems to be little agreement on the answer.

Up to the present waypoint in this series on EM site magnetic fields, we have identified typical sources of time-varying magnetic field intensities, examined salient field characteristics and illustrated correct survey methods. Our goal this month is to analyze data collected at a proposed site and answer the key question of whether or not the candidate site is, as far as magnetic fields go, acceptable for EM use. In the process of analyzing the magnetic field survey data we will define some of the interpretive techniques involved and observe the distinction between localized (a.c. power) and non-localized (geomagnetic) time-varying fields. Finally, we will discuss the implications of EM susceptibility threshold vs. measured field ratios when considering remedial site shielding.

Grains of sand collected from the beach may be examined for a number of reasons. From the youngster who first peers at a handful of beach sand under a magnifying glass to see the various shapes and colors to the sedimentologist who studies sand grains for clues to the questions of plate tectonics, the collection and examination of sand can be a fascinating activity. Dr. Oliver H. Howe, in an interesting article published in 1946, remarked of one sand sampie that under a low power magnifier the various colors of garnet grains contrasted strikingly with the black grains of magnetite, green of epidote and the brilliant grains of quartz.

Two of the aggravations of effectively managing an EM unit are cost containment and effective storage of large numbers of specimens. For the past several years we have enjoyed the benefits of a stub-storage box (for pin-type stubs) available to microscopists without cost. These boxes, which held micro-pipette tips, are regularly discarded by molecular biology and biochemistry labs, in fact, since colleagues have recognized that we use their spent plastic boxes, we have been inundated with boxes originally slated for recycling. While several types of these boxes are available, most measure approximately twelve cm by eight cm and have a plastic platform with ninety-six holes. The boxes hold eight one-inch stubs and six half-inch stubs or thirty-two half-inch stubs.

The electron microscope laboratory at the High Temperature Materials Laboratory in Oak Ridge National Laboratory runs essentially film free. This is possible due to the use of TV-rate and slow-scan CCD cameras together with fast desktop computers connected through Ethernet to network servers for image storage; and a variety of hard copy output devices. In our experience, the functionality of a film-free laboratory goes beyond the simple replacement of film material with some other storage media. For example, the time and effort to produce a final hardcopy image has been reduced effectively from several hours to several minutes. At the same time, data accuracy has increased due to the high linearity of the CCD cameras and data safety is improved due to automated nightly backups.

Those of us who have particle identification problems sometimes have very small samples, say, only a few nanograms - even less sometimes. We also like to make up permanent Aroclor 5442 preparations of these tiny samples for safe keeping and future reference. If we mount such small samples in a normal drop of Aroclor filling an 18 mm diameter coverslip, we may spend a few frustrating minutes looking for the sample in a few acres of Aroclor. My solution is to use a very tiny Arocior droplet under a small coverslip. Ten millimeter or smaller round coverslips are available from Erie Scientific in Portsmouth, New Hampshire.

A.C. magnetic fields exist throughout every EM site. For a given site, then, how does one predict when EM interference problems are likely to occur? Obviously, an accurate, meaningful magnetic field survey is the first step toward evaluating site EM magnetic field compatibility. Consequently, this article in our series will describe measurement equipment and techniques for achieving accurate, unambiguous magnetic field characterization.

In a previous article (Part II: “ACMF/EM Antipathy”, Microscopy Today, November ‘95), we examined several types of sources which produce alternating current magnetic fields (ACMFs). In near proximity, or at sufficiently high power levels, any of these sources (e.g., transformers, power cabling, ground currents, and/or combinations thereof) can affect EM operation. In this article, we will review specific instrumentation and methods for accurate magnetic field survey data collection and interpretation, a necessary prior step for EM interference prediction and resolution.

A microscopist is presented with a special problem when asked to characterize a population of particles. In order to adequately describe the sample, it may be necessary to examine hundreds or even thousands of individual particles, recording the size, shape, identity or other parameters of interest. To manually characterize a statistically significant fraction of the sample could require many hours of tedious work at the scope, followed by still more tedious hours of data reduction. What is needed is a technique to automate the repetitive parts of this process: the recognition and characterization of particles in the sample and the reduction of data and presentation of results. This technique is automated particle analysis.