Microscopy compound microscope

Robert Hooke (1635-1703) was the first to publish results on the microscopy of plants and animals. Using a simple two lens compound microscope, he was able to discern the cells in a thin section of cork. The most famous mierobiologist was Antoni van Leeuwenhoek (1632-1723) who, using just a single lens microscope, was able to describe organisms and tissues, such as bacteria and red blood cells, which were previously not known to exist, hi his lifetime, Leeuwenhoek built over 400 microscopes, each one specifically designed for one specimen only. The highest resolution he was able to achieve was about 2 micrometers. 

Confocal microscopy is a related new technique that provides three-dimensional (3D) optical resolution. Image formation in a confocal microscope is significantly different from a conventional light microscope. Compared with a conventional compound microscope, a modern confocal microscope has two distinctive features in its structure a laser light source and a... 

As shown above, several themes can be extracted from Hooke s contributions to microscopy. First, Hooke explicitly endorsed the use of compound microscopes as dynamic tools for revealing the workings of otherwise unobservable machines. Second, suppositions about any natural body can be drawn from analogical associations to the workings of artificial machines. Third, any machine of the natural world is characterized by its capacities to produce movement, and by its reagent properties. Fourth, to apprehend a machine s capacities, experimenters must acquire a designer s skills of visualization. 

Light microscopy is one of the discipline s primary characterization techniques. It allows the forensic scientist to quickly address that most fundamental question, what does the sample look like before proceeding with more extensive, often destructive, analyses. At all levels of sophistication (from hand lenses to compound microscopes), optical microscopy reveals... 

Additionally, in part because of the pervasive intrusion (or timely arrival) of microprocessors, tools for structure determination are constantly being refined and enlarged in scope. Examples include multidimensional nuclear magnetic resonance (NMR), which is now commonly used for large molecules (the first commercial NMR spectrometers were introduced in the late 1950s) and, even more recently, near-field microscopy, which uses a lensless technique for VIS spectroscopy and thus sidesteps the normal problems of resolution by accumulating structural features a little at a time, is being developed (the first compound microscope became available in 1610). ... 

When a winery considers investment in laboratory equipment, a compound microscope should be a priority. Microscopic capabilities allow winemakers to quickly monitor the progress of alcoholic and malolactic fermentations and to tentatively determine the source of microbiological problems. This chapter oudines basic microscopy as well as techniques to view wine microorganisms. 

The two most useful supplementary techniques for the light microscope are EDS and FTIR microscopy. Energy dispersed x-ray systems (EDS) and Eourier-transform infrared absorption (ETIR) are used by chemical microscopists for elemental analyses (EDS) of inorganic compounds and for organic function group analyses (ETIR) of organic compounds. Insofar as they are able to characterize a tiny sample microscopically by PLM, EDS and ETIR ensure rapid and dependable identification when appHed by a trained chemical microscopist. 

Probably the most extensive use of particle morphology and microscopy has been in the area of chemical microscopy. With this approach, derivatives of the analyte species are prepared, crystallized, and identified through the morphological characteristics of these derivatives [21]. Most of these applications have been superseded by modem methods of analysis, but the microscopic method can still be used by skilled practitioners for the study of trace quantities of analyte. The literature developed during the heyday of chemical microscopy is too large to be reviewed here, but advances in the field are still chronicled in the Annual Reviews issue of Analytical Chemistry [22]. A substantial review of the optical characteristics of organic compounds is available [23]. 

Figure 9.29 Membrane formation by meteoritic amphiphilic compounds (courtesy of David Deamer). A sample of the Murchison meteorite was extracted with the chloroform-methanol-water solvent described by Deamer and Pashley, 1989. Amphiphilic compounds were isolated chromatographically on thin-layer chromatography plates (fraction 1), and a small aliquot ( 1 p,g) was dried on a glass microscope slide. Alkaline carbonate buffer (15 p,l, 10 mM, pH 9.0) was added to the dried sample, followed by a cover slip, and the interaction of the aqueous phase with the sample was followed by phase-contrast and fluorescence microscopy, (a) The sample-buffer interface was 1 min. The aqueous phase penetrated the viscous sample, causing spherical structures to appear at the interface and fall away into the medium, (b) After 30 min, large numbers of vesicular structures are produced as the buffer further penetrates the sample, (c) The vesicular nature of the structures in (b) is clearly demonstrated by fluorescence microscopy. Original magnification in (a) is x 160 in (b) and (c) x 400.

---