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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.
At magnifications higher than 100× moving a slide by hand is not practical. A mechanical stage, typical of medium and higher priced microscopes, allows tiny movements of the slide via control knobs that reposition the sample/slide as desired. If a microscope did not originally have a mechanical stage it may be possible to add one. [citation ...
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.
The practical limit to magnification with a light microscope is around 1300×. Higher magnifications are possible, but it becomes increasingly difficult to maintain image clarity as the magnification increases. [17] Bright-field microscopes have low apparent optical resolution due to the blur of out-of-focus material;
The area provides a reference unit, for example in reference ranges for urine tests. [3]Used for grading of soft tissue tumors: Grading, usually on a scale of I to III, is based on the degree of differentiation, the average number of mitoses per high-power field, cellularity, pleomorphism, and an estimate of the extent of necrosis (presumably a reflection of rate of growth).
A typical magnification for use in dentistry is 2.5×, but dental loupes can be anywhere in the range from 2× to 8×. [14] Optimal magnification is a function of the type of work the doctor does - namely, how much detail he or she needs to see, taking into consideration that when magnification increases, the field of view decreases.
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 ...
Oil-immersion objectives are used only at very large magnifications that require high resolving power. Objectives with high-power magnification have short focal lengths, facilitating the use of oil. The oil is applied to the specimen (conventional microscope), and the stage is raised, immersing the objective in oil.