Like many other people I find myself not having the time to do all the things that I would like to do in a day. I have always wished I could emulate the young lady in Prof. Arthur Bullers (1874-1944) limerick which was published in the December 19,1933 issue of that reputed journal, Punch:

Well, up to now I have not succeeded in my attempts to gain time in this way, but there is hope, there is hope as I will try to make clear in a minute.

First of course, as we all know, the speed of light is finite. This was first demonstrated by Roemer in 1676, He measured the interval between successive eclipses of the intermost satellite of Jupiter (that would be lo, with its sulfur spewing volcanoes), at a time when Jupiter was close to Earth.

Prior to Near-Field Scanning Optical Microscopy (NSOM) there were two major light microscopy techniques; optical and confocal.

In an optical microscope a sample is illuminated with a flood of light. The lighted area is then imaged and magnified by collecting the light that is either reflected from or transmitted through the sample by a series of glass lenses. A color magnified image of the sample may be seen directly or displayed on a TV screen. Even if the lenses could be made perfectly, the resolution and magnification of an optical microscope are limited by diffraction effects to approximately one half of the wavelength of the light that is used. Optical microscopes are used routinely to image the general shape of samples as small as human chromosomes or compact disk bits.

In the early days of biological electron microscopy (the 1950s and 1960s), projection slides of electron micrographs for talks or teaching were generally prepared as 3-1/2″ X 4″ lantern slides, which were shown using large lantern-slide projectors. It was felt by professional electron microscopists that the detail, tones, and general image quality of electron micrographs could be adequately portrayed only in this larger format.

However the large lantern slides were very cumbersome, and most professionals began switching to 2″ X 2″ slides in the early 1970s. Some of us during that period put in a great deal of time trying to work out a procedure for printing EM negatives directly on 2″ X 2″ glass Kodak Projector Slide Plates, following the general approach by which we had previously made the 3-1/4″ X 4″ lantern slides.

How many of the analytical chemists reading this will identify with the following scenario? A customer gives you a sample with a contaminant and asks you to identify the material. Your customer provides a very logical dissertation on what the material is likely to be. With that bias firmly entrenched in your mind, you proceed with the analysis, fully expecting to find what your customer said you should. However, during the course of your analysis, you discover that the contaminant is something completely different than expected. Now you are presented with the dilemma of facing that customer to explain the “unexpected” result. You are immediately put on the defensive by being accused of not having properly calibrated instruments or you have obviously contaminated the sample with something else during sample preparation, etc. These situations occur in laboratories all over the world.

Questions about samples consisting entirely of a collection of microparticles come from people involved in a wide variety of industries dealing with powders, from Pharmaceuticals to industrial minerals, powdered coatings to industrial hygiene concerns. The questions often asked are morphological. How big? How long? How wide?, and often pose a special problem for the microscopist. The time and tedium associated with answering these questions for a significant subset of the sample particles without an automated system causes the cost to skyrocket and sends the requester off to the light scatterers who at least give cheap answers, never mind that nobody knows what they really mean (What is the average size of a particle with an aspect ratio of 5? And did you calibrate your scattering system for my particles in my dispersant or are you still using latex spheres in water?). A common additional question is “How many are quartz, or titania, or organic, or….?” The inherent advantages of microscopy—the ability to determine detailed morphology in two dimensions (and maybe three), and to discriminate different particle types in a mixture—were usually overwhelmed by the cost and time involved.