Recent Internet postings on the Microscopy listserver indicate paradoxical views on the personal protective equipment (PPE) necessary to handle liquid nitrogen (LN2) safely. Those views range from full protective gear to, somewhat facetiously, complete nudity. The crux of the paradox is that both extremes have points of validity.

The gist of preventing frostbite or cold injury to the skin is to prevent continuous contact with LN2. The physics of the Leidenfrost effect (LE) protects the skin from momentary contact or splashes of LN2. A layer of gas between the LN2 and the skin prevents significant heat transfer from the skin, stopping damage. The LE does not apply to inadvertent splashes of LN2 to the cornea. Alternatively, using protective equipment insulates the skin and prevents trapping of the cryogen by allowing the LN2 to run off.

Over the past decade the achievable resolution of the scanning electron microscope (SEM) in secondary electron (SE) imaging mode has improved by about one order of magnitude. In fact, instruments capable of demonstrating a resolution of one nanometer and exhibiting a probe size of less than 0.6 nm are not available. Continued improvements in electronoptics, electron sources, and in electronic and mechanical stability promise even smaller probe sizes that still contain adequate current for imaging, it is therefore relevant to consider what resolution might ultimately be achievable with an SEM in SE mode.

Often times one is asked the question "how can the optical microscope be used to make quantitative measurements?" The microscope certainly lets one observe the sample {whatever the sample may be) and make qualitative statements about what is it one is looking at. It has been used for various purposes from just visual observation in brightfield, reflection and the one that is near and dear to my heart, observations under crossed polarizers. This certainly allows one to identify materials as being isotropic or anisotropic. If one works on materials like liquid crystals, an optical microscope is a tool that is used all the time. It certainly allows for identification of various phases of liquid crystals based on the defects and textures that can be observed. All of this is somewhat qualitative in nature. By that I mean that the observations do not lend themselves to obtain, say for example, refractive index or birefringence of the material. I would like to describe a technique that will allow one to do just that.

Mr. John Mardinly of Intel Corporation, former president of NCSM, gave the Physical Science Presentation at the December 7, 1995, NCSM meeting held in Albany. CA. “Applications of Microscopy in the Microelectronics Industry” was the speaker's topic. Mr. Mardinly began by giving some background on integrated circuits. He had wafers to show as examples while stating that the value of each one exceeds $100,000 at S500 per chip and there are numerous chips on each wafer. The individual chip he showed had 3.1 million transistors, with 237 pins and 237 connections per device. The new Pentium Pro will have a mind-boggling 5.5 million transistors packed onto the same size chip.

Having shopped for an inexpensive but powerful digital imaging system for the last four years, I have finally found a device that will satisfy even the most frugal budget. The Snappy Video Snapshot by Play, Incl, is a 24-bit true color frame grabber that plugs into your PC printer port. After plugging the Snappy device into your printer port (Figure 1) and spending approximately six minutes loading the Snappy software provided, you can connect a color or black and white camera, VCR, or television set and capture your first digital image. Because the device plugs into a printer port, it is completely portable. A switch box is needed if you will be changing between digital image acquisition and printing tasks frequently.

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.