Microscopes compound

A confocal microscope using ultraviolet light and a 1.30-NA objective is expected to produce a resolution of about 0.07 p.m (70 nm), but no such instmment has been developed. There are confocal attachments that fit on almost any compound microscope. If one of the eady twentieth century ultraviolet microscopes or a Burch reflected optics scope can be found, the shorter wavelength and improved contrast would make possible better resolution than any compound light microscope. 

Filthy conditions, due to rodent or insect population, may be observed in a grain warehouse. The inspector notes rat-chewed flour sacks and sacks contaminated with rat excrement. He removes a sample of sacking and flour from such contaminated areas and submits them to the analyst. Urine fluoresces under ultraviolet light. Where rodent urine is to be confirmed, the xanthydrol test is one of several that may be used. Excreta pellets may be moistened with water or an appropriate clearing solution and crushed for observation under the compound microscope. The presence of striated hair fragments indicates rodent excrement. 

Figure 2.1 Hooke s compound microscope drawn by himself.

The compound microscope is essentially a two-stage magnifier. One lens (or combination of lenses), termed the objective, forms a real image of an illuminated or self-luminous object, and a second lens (or combination of lenses), denoted as the eyepiece, acts as a simple magnifier whose object is the real image formed... 

Fluorescence microscope equipped with appropriate excitation filter, dichroic mirror, and barrier filter. For this example, an Olympus BHT compound microscope equipped with a BP490 excitation filter, BH-2DM500 dichroic mirror, and a LP515 barrier filter is used. 

Flying Spot Microscope, A television-type scanner illuminates specimen in compound microscope to obtn pictures superior in size, brightness, contrast resolution to those of normal microscope. Discrete particles are automatically oounted and sized Ref F. Roberts, J.Z. Young D. Causley, Electronics 26, 137—39 (July 1953)... 

The electron microscope is an optical instrument with magnification much higher than any other known instrument (magnifications of up to 100000 are obtainable, compared with 1000 for the ordinary compound microscope) Essentially, an electron microscope consists of a source of electrons, sometimes called an electron gun (negative high voltage), and a series of devices serving as "lenses the first is a condenser lens, then an objective and a third lens which.functions as a... 

F results in a magnified image produced at a considerable distance from F on the other side of the the lens, which is convenient for viewing. In a compound microscope, the most common type, an additional lens, the eyepiece, is added to magnify the image produced by the objective lens. 

Fig. 1. Optical pathway of (a) a compound microscope and (b) a phase-contrast microscope.

Stir the initial sample gently to mix it and put a drop onto a microscope slide. Under a compound microscope count the number of cells in the first 50 colonies encountered. If the counting is all to be done in a single class, then this sample could be preserved (Lugofs solution or glutaraldehyde) and counted later. If the microscope is sufficiently powerful, drawings of several colonies can be made to estimate roughly the spine sizes on the cells. 

After 3 days to 1 week (longer would be fine, but would necessitate more daily application of experimental and control water) stir the samples gently to mix. For each replicate of each treatment place a drop under the compound microscope and record the number of cells in the first 50 colonies encountered. Again, observe the spines if the microscope s resolution permits (Data Sheet 15.1). 

Since the time of the Romans, it was realized that certain shapes of glass had properties that could magnify objects. By the year 1300, these early crude lenses were being used as corrective eyeglasses. It wasn t until the late 1500s, however, that the first compound microscopes were developed. 

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. 

A typical compound microscope. Carolina Biological Supply Company/Phototake NYC Reproduced by permission. 

Compound microscope—light microscope which uses two or more glass lenses to produce an image. 

Fig. 4.—Diagram illustrating optics of a compound microscope in use. Pi, Upper focal plane of objective P2, Lower focal plane of eyepiece A, Optical tube length = distance between Fi and P2 Oi, object Os, real image in Pj, transposed by the eollective lens, to Oj, real image in eyepiece diaphragm O4, virtual image formed at the projection distance C, 250 mm. from EP, eyepoint CD, condenser diaphragm L, mechanical tube length (160 mm.) i, 2, 3, three pencils of parallel light coming from different points of a distant illuminant, for instance, a white cloud, which illuminate three different points of the object. (Courtesy of Bausch and Lomb Optical Co.)...

The volume of water filtered through the plankton sampling net was carefully noted. For raw water, e.g. surface-water or reservoir water and influent slow sand filter, a sample of 15—20L was collected. For treated water, e.g. filtrate of rapid filters, 150 L samples were taken. The concentrate, collected into a small cylindrical container, was quantitatively carried over into a calibrated small polyethene bottle after that the small container was immediately rinsed with demi-water and the calibrated recipient was filled up to 50 mL. Netplankton samples were preserved with formalin. If necessary, further concentration was performed by a secondary nitration through a plankton net with size aperture of 30 nm. A suvolume of 50 juL of the concentrated sample, taken with a micropipet, was used for mounting and counting the preparation by means of a compound microscope. 

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