Microscopy

Microscopy - visual study of various small objects (from 0.2 to 0,0000002 mm) by means of a microscope (with an increase from a few dozen to hundreds of thousands of times).
Ordinary light microscope (see) is used in cases when the structure of the object is enough contrast and distinct. Light microscopy increases and moving images, to conduct microphoto and filming, long to see one and the same object. In cases when objects microscopy weak contrast, to study them use special methods of light microscopy.
1. A dark-field microscopy (and its variant, ultramicroscopy) is based on the fact that the smallest particles, which are beyond the resolution of the microscope become visible in the rays coming at such a steep angle that the lens is not directly fall (powerful beam of light side). The lens gets only light reflected from these particles;
they look glowing spots on a dark background.
2. Phase-contrast microscopy dramatically improves the contrast of the image of object. Principle of the method is to identify shifts the phase of light vibrations that occur when light passes through the structure in which the refractive index is different from the refractive index of the surrounding environment. Phase shifts in the eye are not recovered, but in a special phase-contrast microscope structure that has a higher refractive index (even completely transparent)are darker (or lighter depending on the device design)than the surrounding background.
Such picture is observed during the so-called amplitude-contrast or anopthalmia microscopy.
3. Ultraviolet microscopy, based on the ability of some substances selectively absorb ultraviolet light with the wavelength, principally almost no different from an ordinary light microscope and using microscopes with quartz or reflective (mirror) optics. The image is considered to fluorescense the screen visually and photographed. Microscope objects allows to identify the tested substance, without the use of color.
4. Fluorescent (fluorescent) microscopy allows to study as their own (primary) fluorescence of a number of substances and secondary fluorescence caused by staining cellular structures with special dyes - fluorochrome. Principle of the method is that some substances light irradiation begin to glow themselves. For excitation of fluorescence in visible part of the spectrum are usually blue or ultraviolet light.
Many substances, fluorescent not in the visible region (especially nucleic acids), when illuminated with UV rays begin to floorestimate and can be detected without the use of fluorochromes. Secondary fluorescence is immunofluorescence, based on the interaction of immune protein fluorochrome. Cm. also Microscope, Microscopic techniques.

Microscopy (from the Greek. mikros - small and skopeo - examine, investigate) is a method of the visual study of small objects at magnifications from several tens to hundreds of thousands of times. For modern microscopy is available to almost all body sizes ranging from 0.2 to 0,0000002 mm Distinguish between light and electronic Meters of Light microscopy provides a useful increase up to 2-3 thousand times, color and moving image of a living object is the possibility of microinnochange and long-term observations of the same object, the evaluation of the dynamics and chemistry. It is irreplaceable in diagnostic and research work, routinely necessary in practical medicine.
Electron microscopy (see) allows you to work at magnifications up to many hundreds of thousands of times, but only with a dried, dead or priznatelen objects. Its scientific value is extremely high, the use of practical, including diagnostic purposes is possible, but not developed. Common as in light and electron microscopy remains description forms on a zoomed image object and matching forms with different functional, chemical and other properties.
The resolution and contrast - the main characteristics of any microscope. The resolution is quantitatively expressed by the minimum distance at which there are two points that demonstrate the microscope separately (the minimum allowed distance, or resolution). Resolution of the human eye in best mode vision is equal to 0,2 mm Image of two points located closer one to another 0.2 mm, merge, and the naked eye detects instead of two points some figure (picture geometrically not consistent with the real object). The same error occurs in any optical instrument building unresolved image. To see the unresolved object is possible only under the condition that the light is considerably brighter than the background (a typical example unresolved image - the stars in the night sky). Such an object, regardless of its real shape looks like a bright point. For unresolved object any increase is useless, because in any circumstances its actual form and details cannot be shown and discussed. Resolution light microscope is 0.0002 reaches mm Consequently, with its help it is possible to reach maximum increase in 1000-2000 times. The most experienced microscopists, using the best means of improving contrast, receive a good micrograph when the increases of the order of 3000 - 4000 times. This and the limited opportunities of useful increasing light microscope.
Image contrast is the difference in brightness of the background image. If the brightness differ by less than 3-4%, the difference may not be captured nor eye, nor a photographic plate; the image will not be visible even if the microscope allows its details. The contrast depends on the properties of the object that changes luminous flux in comparison with the background and the ability optics to capture emerging differences in the properties of the ray.
The natural limits of the light microscope wave nature of light. Construction of modern microscopes worked out so well that the upper limits of their technical capabilities almost coincide with those of the natural, physical boundaries. However, there are very many factors that impair the operation mode of the microscope and reduce scientific and practical value of the results. Most of these factors is controlled by the knowledge and ability of microscopist. Compliance with the rules of microscopic techniques (see) is mandatory for skilled work, i.e. for the approximation of the real results of the microscope to the computational capabilities of this device.