Temporal resolution has long been a challenge to microscopists. Certainly, spatial resolution has occupied center stage, but we're all concerned about what happens over time in a biologic system, for example, a cell. Tags such as green fluorescent protein (GFP) have been used with confocal microscopy and other light microscopic techniques to achieve outstanding temporal resolution, but good spatial and temporal resolution have proven to be difficult to achieve simultaneously. This has been accomplished in a remarkable study by Guido Gaietta, Thomas Deerinck, Stephen Adams, James Bouwer, Oded Tour, Dale Laird, Gina Sosinsky, Roger Tsien, and Mark Ellisman, who demonstrated a pulse-chase technique that correlates with both fluorescence and electron microscopy.

It was Castaing who many years ago lamented “First 1 realized that in massive samples which concerned the metallurgists i would have to give up the splendid resolving power that I had cheerfully envisaged, as 1 became aware of the terrific path that my electrons would perform haphazardly in the sample before agreeing to stop. I had to limit my ambitions to analyzing volumes of a few cubic micrometers. This was a big disappointment. ..”. In the early days most instruments for imaging and microanalysis of bulk samples were restricted to operating only at relatively high beam energies (∼30kV) and for many (and perhaps too many) years this became the accepted operating procedure. However, we now know there are substantial advantages (pros) in using lower, and in some cases much lower, voltages; but also some significant limitations (cons). So what is possible?

Many us who use microscopes are interested in the internal structure or components of three-dimensional objects. Often we must section these objects to observe these internal components. For many years, microtomes have been used to make physical sections, but in recent years confocal microscopes, MR imaging, CT scanners, and even standard optical microscopes have been used to obtain “optical” sections. Two-dimensional images of these different types of sections can be used to extract three-dimensional quantitative information about the objects and their internal components, The sectioning process reduces the observed dimensions of the object and components. With apologies to Rene Magritte, the structure portrayed in Figure 1 is not a three-dimensional glomerulus but a two-dimensional profile of a glomerulus. In most cases, interest is on the structure of the three-dimensional object and not the structure in the two-dimensional image. Thus, care must be taken when obtaining and interpreting data from two-dimensional images.

Adobe Photoshop may not come to mind as a program that is useful for segmenting (separating regions of interest from other visual information), but, in many ways, its functions can help scientists gain several end results. These include the ability to fully or partially automate the segmentation of entire directories of image files, the ability to better separate regions of interest from background, and the ability to narrow histograms (making the selection of a grayscale value less subjective when setting a threshold value).

My first universal student microscope, shown in Figure 1, began life as a Monolux microscope from the 1960rs. Its development into a universal student microscope began when my wife wanted a polarized light microscope with the ability to photograph microscopic crystals under a cover glass for their artistic value. My background as a metallurgist was with the reflected light metallurgical microscope, I have also designed and built vertical illuminators for brightfield illumination of complete metal log raphic specimens using a fiber optic light guide end as the light source with lens configurations giving an imaged field diaphragm and an illumination aperture diaphragm imaged in the aperture of the macro lens.

Cross-section transmission electron microscope (TEM) specimen preparation of Ill-V materials using conventional methods can be a painful and time-consuming activity, with a day or more from receipt of a sample to examination in the TEM being the norm. This article describes the cross-section TEM specimen preparation technique used at Bookham Caswell. The usual time from start to finish is <1 hour. Up to 10 samples can be prepared at once, depending upon sample type. Most of the tools used are widely available and inexpensive, making the technique ideal for use in institutions with limited resources.

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.

Microspherules (MS) ranging in size from 50μm to 425μm were discovered at Westwater, Utah in 1999. Examination of these particles using a scanning electron microscope identifies certain physical features that support an extraterrestrial (ET) provenance for these objects. Energy dispersive spectrometry (EDS) was used to determine the qualitative chemistry of these particles.