microscope (redirected from specular microscope)

microscope /mi·cro·scope/ (mi´kro-skōp) an instrument used to obtain an enlarged image of small objects and reveal details of structure not otherwise distinguishable.

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acoustic microscope  one using very high frequency ultrasound waves, which are focused on the object; the reflected beam is converted to an image by electronic processing.

binocular microscope  one with two eyepieces, permitting use of both eyes.

compound microscope  one consisting of two lens systems.

corneal microscope  one with a lens of high magnifying power, for observing minute changes in the cornea and iris.

darkfield microscope  one designed to permit diversion of light rays and illumination from the side, so that details appear light against a dark background.

electron microscope  one in which an electron beam, instead of light, forms an image for viewing on a fluorescent screen, or for photography.

fluorescence microscope  one used for the examination of specimens stained with fluorochromes or fluorochrome complexes, e.g., a fluorescein-labeled antibody, which fluoresces in ultraviolet light.

infrared microscope  one in which radiation of 800 nm. or longer wavelength is used as the image-forming energy.

light microscope  one in which the specimen is viewed under visible light.

phase microscope , phase-contrast microscope one altering the phase relationships of the light passing through and that passing around the object, the contrast permitting visualization without the necessity of staining or other special preparation.

scanning microscope , scanning electron microscope an electron microscope in which a beam of electrons scans over a specimen point by point and builds up an image on the fluorescent screen of a cathode ray tube.

simple microscope  one consisting of a single lens.

slit lamp microscope  a corneal microscope with a special attachment that permits examination of the endothelium on the posterior surface of the cornea.

stereoscopic microscope  a binocular microscope modified to give a three-dimensional view of the specimen.

ultraviolet microscope  one that utilizes reflecting optics or quartz and other ultraviolet-transmitting lenses.

x-ray microscope  one in which x-rays are used instead of light, the image usually being reproduced on film.

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mi·cro·scope (mkr-skp)

n.

1. An optical instrument that uses a lens or a combination of lenses to produce magnified images of small objects, especially of objects too small to be seen by the unaided eye.

2. An instrument, such as an electron microscope, that uses electronic, acoustic, or other processes to magnify objects.

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microscope

[mī′krəskōp′]

Etymology: Gk, mikros, small, skopein, to view

an instrument with lenses for viewing very small objects. Types of microscopes include the acoustic microscope and the electron microscope.

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microscope,

n an instrument containing a powerful lens system for magnifying and viewing near objects.

Microscope, Confocal Laser Scanning (CLSM),

n.pr a microscope equipped with a laser beam light source, electronic image detector, and computer for image storage and processing that is used in the laboratory to perform high-resolution, three-dimensional microscopy.

microscope, dark-field,

n a microscope that has a special condenser and objective with a diaphragm or stop by which light is scattered from the object with the result that the object appears bright and the background dark.

microscope, electron,

n a microsope in which electron beams with wavelengths shorter than those of visible light are used in place of visible light, allowing much greater resolution and magnification of the object.

microscope, electron, scanning (SEM),

n an electron microscope capable of reflecting electrons from the specimen surface, resulting in a three-dimensional image of the surface that provides both high resolution and a great depth of focus view of the object.

microscope, interference,

n a microscope designed to split entering light into two beams that pass through the specimen and are recombined in the image plane, allowing visualization of refractile object details that are not possible with a single beam.

microscope, phase-contrast,

n a specially constructed microscope that has a special condenser and objective containing a phase-shifting mechanism whereby small differences in refraction can be made visible to intensity or contrast in the images. It is particularly helpful in examining living or unstained cells and tissues. This is an excellent aid in the education and motivation of patients in the understanding and control of dental plaque.

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microscope

an instrument used to obtain an enlarged image of small objects and reveal details of structure not otherwise distinguishable.

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acoustic microscope

one using very high frequency ultrasound waves, which are focused on the object; the reflected beam is converted to an image by electronic processing.

binocular microscope

one with two eyepieces, permitting use of both eyes simultaneously.

bright-field microscope

the standard bench microscope used in histology and requiring stained tissue sections.

compound microscope

the standard laboratory microscope used in veterinary science; consists of a two lens system whereby the image formed by the system near the object (objective) is magnified by the one nearer the eye (eyepiece).

darkfield microscope

used for examining unstained, often living cells, in which light is only directed into the objective lens if it is deflected by an object in its path. The object is thus viewed as a white structure in an otherwise black (darkfield) background.

electron microscope

one using an electron beam of very short wavelength as the source of illumination. It has a resolving power of 2 nm (which is 100 times greater than with the light microscope). Includes the transmission electron microscope and the scanning electron microscope (below). See also immunoelectron microscopy.

fluorescence microscope

one used for the examination of specimens stained with fluorochromes or fluorochrome complexes, e.g. a fluorescein-labeled antibody, which fluoresces in ultraviolet light. See also fluorescence microscopy.

interference microscope

a microscope similar to the phase contrast microscope but delivers a three-dimensional image. Called also Nomarski interference phase microscope.

light microscope

used for examining unstained or stained particles or the cellular structure of tissues that have been cut into sections and stained. It has a resolving power of 0.2 μm. Modern light microscopes have an eyepiece and objective lenses which provide magnification, and a condenser beneath the stage which gathers and focuses light on the object being examined.

operating microscope

one designed for use in performance of delicate surgical procedures, e.g. on the middle ear, eye or small vessels of the heart.

phase microscope, phase-contrast microscope

a form of light microscope useful for examining living, unstained structures, including animal cells and bacteria, e.g. leptospira. The phase of the light wave passing through different structures in the cell, e.g. nucleus vs. thin part of the cytoplasm, is changed by different amounts and thereby provides contrast.

polarizing microscope

based on the phenomenon of birefringence; useful in the study of bone and muscle.

scanning electron microscope (SEM)

an electron microscope that produces a high-magnification image of the surface of a metal-coated specimen (shadow casting) by scanning an electron beam and building up an image from the electrons reflected at each point. Particularly useful for determining the three-dimensional structure of objects.

simple microscope

one that consists of a single lens.

specular microscope

one used in the examination of the corneal endothelium.

stereoscopic microscope

a binocular microscope modified to give a three-dimensional view of the specimen.

surgical microscope

see operating microscope (above).

transmission electron microscope, TEM

one that resembles an inverted light microscope in that the beam of electrons generated from a heated filament at the top of the instrument passes down through a column where it is focused by magnetic coils (lenses) and is differentially scattered when it passes through the specimen. The image is recorded either on a photographic plate or on a phosphorescent screen.

ultraviolet microscope

uses an ultraviolet light source; useful in histochemical studies; only photographic images are available.

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microscope

An optical instrument for magnifying small near objects. It can consist of a single converging lens such as a loupe (simple microscope) or of two or more lenses or lens systems (compound microscope) (Fig. M11). In this latter case, one lens or lens system serves as an objective to form real and magnified images of the object while the other lens or lens system serves as an eyepiece to examine the aerial image formed by the objective. The final image is inverted with respect to the object. It can use light or a beam of electrons (electron microscope) which produces magnification some 50 to 100 times greater than with light. The magnification, M, of a light microscope, adjusted for a final image at infinity, is equal to

M = M_o ✕ M_e

where M_o is the lateral magnification of the objective, and M_e the angular magnification of the eyepiece. See eyepiece; immersion lens; objective; stage.
confocal microscope A microscope that provides viewing of cells, organisms (such as bacteria or fungi) and other structures within various tissues, in living patients. It allows each layer of a tissue to be viewed with much greater clarity than with a conventional microscope because signals from the viewed layer and the illumination beam have the same focus, while elements above or below the focal plane are out of focus and usually filtered out. The instrument has been used to investigate and diagnose corneal disease processes, including dystrophies and infectious keratitis, or to follow corneal healing after laser or traditional surgery. In addition, the instrument scans the object of interest by varying the plane of focus to form an image in three dimensions, of higher contrast and resolution than provided by a specular microscope. See confocal scanning laser ophthalmoscope.
microscope magnification See microscope.
slit-lamp microscope Compound microscope used in conjunction with a slit-lamp. It is designed to have a working distance of about 90-125 mm to allow room for the clinician or for placing certain accessories such as a tonometer or pachometer. Slit-lamp microscopes have a magnification that varies usually within the range of ✕6 to ✕40. See working distance; slit-lamp.
specular microscope A light microscope utilizing specular reflection to view the component layers of the cornea and particularly to observe and photograph the endothelium. It consists of an objective which is divided longitudinally. Light in the form of a slit beam is directed down one half and is reflected from the cornea-aqueous interface to the other half of the objective to form a visible and photographic image of the endothelium. The microscope is usually fitted with a ✕ 40 water immersion objective which has a working distance of 1.6 mm. The cornea is covered with silicone fluid into which the objective tip is immersed. Good resolution is achieved provided that the width of the slit beam is kept small, to reduce the light scatter from the overlying corneal layers. This microscope allows examination of the corneal endothelium in vitro.For clinical measurements, the specular microscope is mounted horizontally using an objective with less magnification (usually ✕ 20). The tip of the microscope has a glass-windowed, fluid-filled, screw-on cap, which applanates the cornea over a very small area. The field of view is usually increased by the insertion of a + 10 D into the incident light path before the objective. Photomicrography is accomplished with a flash unit, as otherwise eye movements make photography with long exposure impossible. However, corneal anaesthesia is necessary and clear images of the endothelium are not possible if the cornea is oedematous. For these reasons new systems have been developed which fit on a slit-lamp and facilitate photography. Their magnification is greater than other slit-lamps, being ✕ 40 to ✕ 70, and they do not require contact with the cornea as they have long working distances. Specular microscopy is used to monitor changes in corneal endothelium in contact lens wearers, especially those wearing extended wear lenses. See working distance; confocal microscope; endothelial polymegethism.

Fig. M11 Optical principle of a compound microscope (F_o, F′_o, first and second principal focus of the objective; F_e, F′_e, first and second principal focus of the eyepiece; h, h′, object and image formed by the objective)