Advances in charged couple device (CCD) design, low cast processor power, cheap memory and dropping prices of digital cameras over the last few years have made the CCD digital camera art attractive alternative to the film camera for many imaging applications. This is especially true in macro imaging where it appears likely that digital cameras will replace film cameras (curiously, Long (2001), says otherwise). As will be described here, a digital camera equipped with a quality macro-zoom lens, generates images with a depth of field (e.g., Fig. 1) that greatly surpass images produced by a film camera with a comparable lens system.

In the past few weeks we have been very involved jn setting up new QemSCANs, MLA's and analytical scanning systems and it Is amazing how many times we had to explain the relationship between accuracy, magnification, scan speed, resolution and the resulting time taken to scan over a number of samples.

Let me explain. All the above systems are used to scan over a number of geological samples using a scanning electron microscope and EDX analytical systems. In most cases the users are simply looking for a phase/type of mineral within each sample. They then need to analyse it. The main criteria being that they scan through a large number of such samples in as short a time as possible.

Polymer films and fibers can readily be imaged in a “top-view“ mode by depositing the sample directly on a transmission electron microscopy (TEM) support grid. Sample preparation of thin polymer films and fibers for cross-sectional views in the electron microscope, however, is a major challenge. Owing to their small dimensions, the films or fibers cannot be mounted alone, because they will not remain immobilized In the microtome, even at low temperatures. Brittle polymers complicate sample preparation even further because they tend to break due to the mechanical stresses exerted on them by the microtome sample holder and the knife. Such sections often jump off the knife-edge or the sample film, thus preventing a systematic collection of thin sections. Similar arguments apply for cross-sectional atomic force microscopy (AFM).

Transmission electron microscopy (TEM) continues to play an important role in diagnostic surgical pathology, particularly in such areas as kidney pathology and tumor diagnosis, among others. Diagnostic TEM is subject to unique time constraints, quality control regulations, and other problems not seen in other TEM applications. The diagnostic TEM laboratory must produce high-quality electron microscopy on small samples which frequently are suboptirnal in fixation and tissue quality due to the pathology involved and time factors associated with biopsy and surgery.

Cast irons belong to a family of iron-carbon (Fe - C) alloys with free carbon in the form of graphite, a very soft constituent of iron microstructures, that improves machinability and damping properties of castings, or combined carbon, in the form of cementite, that improves wear resistance. Graphitic cast irons include grey iron, compacted iron, malleable iron, and ductile iron, Cementite irons include white cast iron and alloy cast irons. Solidification of graphite directly from molten metal takes place between 1145°C (2093 °F) and 1152 °C (2105 °F), according to the Fe-C equilibrium diagram. The above considerations regard only pure Fe - C alloys.

SEM users are familiar with two forms of contrast in SEM images: topographic contrast and atomic number contrast. We can now add a third form of contrast. Contrast can arise due to the different orientation of grains in the sample. However, in normal operation this con trast is very weak, since in the SEM the beam includes a range of incident angles. This has the effect of averaging out diffraction contrast from the different orientations of the grains. This contrast is generally much stronger when the trast is very weak, since in the SEM the beam includes a range of incident angles. This has the effect of averaging out diffraction contrast from the different orientations of the grains. This contrast is generally much stronger when the incident beam is an ion beam rather than an electron beam — contrast between the grains is strong in ion-beam images but not in normal SEM images.

The traditional polarizing microscope equipped with crossed linear polarizers shows a picture in which the image contrast of a birefringent object depends on both the amount of relative retardation induced by the object and the orientation of its principal axis. For example, if the orientation of the principal axis is parallel to one of the polarizers, then the birefringent object becomes invisible. For best visibility, the principal axis must be oriented at 45° to the polarizers. In addition, the image intensity of the object is proportional to the square of the sine of the relative phase shift between the ordinary and the extraordinary ray passing through the object. The addition of a waveplate as compensator to the optical train provides the opportunity to improve the contrast and measure the relative retardation, but the principal restrictions of orientation dependence and non-linear image contrast remains.

Microanalysis using an EDS on an SEM are sometimes asked whether two samples are of different composition, or if different regions in the same sample vary in composition, A best educated guess may be that differences of a few percent can be distinguished under optimized conditions that include favorable data collection times and count rates, stable instrument operation, and well prepared samples and standards that remain free of contamination. Another frequently asked question is whether it is possible to detect a given amount of a particular element in a sample.

Commonly known as 'water bears', tardigrades are a phylum of microscopic animals that can be found living on mosses and lichens all over the world. The name Tardigrada means 'slow walker' which describes their sluggish, deliberate movements. Between these slow movements and their 'teddy bear' like appearance, tardigrades are the only really “cute” invertebrate. Tardigrades, Echiniscus sp., are generally less than 500 micrometers in length and require at least40-power magnification to be seen clearly.

D. Sherman: This session centers on approaches to maintaining major equipment—primarily electron microscopes. I thought we ought to look at how effective it is to seivice with onsite engineers. So with that I would like to start us out with Pat McGinley from JEOL.

Pat is a long—time JEOL employee. He started out as a service engineer in 1976 and is currently Vice President of Service and a member of the Board of Directors for JEOL USA.

What is the best cantilever for intermittent contact mode (often called Tapping Mode™) atomic force microscope (AFM) imaging under water? This is a question I hear often and one that recently generated some interesting discussion on an AFM newsgroup (more on the newsgroup below). The ability of the AFM to image samples En physiologically relevant environments has made it a popular technique in the biological sciences. However, because scanning the AFM tip in contact mode easily perturbs many biological samples, it was the advent of intermittent contact modes that lead to AFM's widespread use in biology.

Fluorescence labeling techniques are quite useful to microscopists. Not only can fluorescent probes label sub-cellular structures with a high degree of specificity, they can also do so with a very high degree of sensitivity. This combination of specificity and sensitivity permits observations of cellular events that are not always visible using traditional methodologies, such as brightfield microscopy.

In the world of fluorescent imaging, the need to colorize grayscale images can be an everyday task. Yet, when all too many of these colorized images go to publication, the results appear to contain undifferentiated blobs of a saturated color, rather than images that contain gradations of color.

While very small objects need to be as bright as possible in order to make these objects apparent (e.g. bacteria under low magnification), and while too many push the gain on photomultiplier tubes in order to top grayscale values off at 255 (on an 8-bit range) in order to show unquestionable colocalization, only the former can be defended on the basis of revealing lost features.