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With an optical microscope having a high numerical aperture and using oil immersion, the best possible resolution is 200 nm corresponding to a magnification of around 1200×. Without oil immersion, the maximum usable magnification is around 800×. For details, see limitations of optical microscopes.
While larger magnifications are possible no additional details of the object are resolved. [citation needed] Alternatives to optical microscopy which do not use visible light include scanning electron microscopy and transmission electron microscopy and scanning probe microscopy and as a result, can achieve much greater magnifications.
At higher magnifications, the image quality of a simple magnifying glass becomes poor due to optical aberrations, particularly spherical aberration. When more magnification or a better image is required, other types of hand magnifier are typically used. A Coddington magnifier provides higher magnification with improved image quality.
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. [3] Bright-field microscopes have low apparent optical resolution due to the blur of out-of-focus material;
Small specimens necessarily require intense illumination, especially at high magnifications, and this is usually provided by a fibre-optic light source. Fiber optics utilize halogen lamps which provide high light output for a given power input. The lamps are small enough to be fitted easily near the microscope, although they often need cooling ...
One of the most important properties of microscope objectives is their magnification.The magnification typically ranges from 4× to 100×. It is combined with the magnification of the eyepiece to determine the overall magnification of the microscope; a 4× objective with a 10× eyepiece produces an image that is 40 times the size of the object.
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.
A photographic loupe for examining film and prints. A loupe (/ ˈ l uː p / LOOP) is a simple, small magnification device used to see small details more closely. [1] They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye.