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A microscope, which makes a small object appear as a much larger image at a comfortable distance for viewing. A microscope is similar in layout to a telescope except that the object being viewed is close to the objective, which is usually much smaller than the eyepiece. A slide projector, which projects a large image of a small slide on a screen.
This image shows a cross-section of the vascular tissue in a plant stem. Bright-field microscopy ( BF ) is the simplest of all the optical microscopy illumination techniques. Sample illumination is transmitted (i.e., illuminated from below and observed from above) white light , and contrast in the sample is caused by attenuation of the ...
An account of the early history of scanning electron microscopy has been presented by McMullan. [2] [3] Although Max Knoll produced a photo with a 50 mm object-field-width showing channeling contrast by the use of an electron beam scanner, [4] it was Manfred von Ardenne who in 1937 invented [5] a microscope with high resolution by scanning a very small raster with a demagnified and finely ...
Created Date: 8/30/2012 4:52:52 PM
The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century.
The stereo, stereoscopic or dissecting microscope is an optical microscope variant designed for low magnification observation of a sample, typically using light reflected from the surface of an object rather than transmitted through it. The instrument uses two separate optical paths with two objectives and eyepieces to provide slightly ...
Typical magnifications for viewing slides full-frame depend on image format; 35 mm frames (24×36 mm slides to 38×38 mm superslides) are best viewed at ca. 5×, while ca. 3× is optimal for viewing medium format slides (6×4.5 cm / 6×6 cm / 6×7 cm). Often, a 10× loupe is used to examine critical sharpness.
A typical microscope has three or four objective lenses with different magnifications, screwed into a circular "nosepiece" which may be rotated to select the required lens. These lenses are often color coded for easier use. The least powerful lens is called the scanning objective lens, and is typically a 4× objective.