microscope

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 or other processes to magnify objects.

An instrument used to obtain an enlarged image of a small object. The image may be seen, photographed, or sensed by photocells or other receivers, depending upon the nature of the image and the use to be made of the information of the image.

A simple microscope, hand lens, or magnifier usually is a round piece of transparent material, ground thinner at the edge than at the center, which can form an enlarged image of a small object. Commonly, simple microscopes are double convex or planoconvex lenses, or systems of lenses acting together to form the image.

The compound microscope utilizes two lenses or lens systems. One lens system forms an enlarged image of the object and the second magnifies the image formed by the first. The total magnification is then the product of the magnifications of both lens systems (see illustration).

Compound microscope diagram. (After F. A. Jenkins and H. E. White, Fundamentals of Optics, 4th ed., McGraw-Hill, 1976)

The typical compound microscope consists of a stand, a stage to hold the specimen, a movable body-tube containing the two lens systems, and mechanical controls for easy movement of the body and the specimen. The lens system nearest the specimen is called the objective; the one nearest the eye is called the eyepiece or ocular. A mirror is placed under the stage to reflect light into the instrument when the illumination is not built into the stand. For objectives of higher numerical aperture than 0.4, a condenser is provided under the stage to increase the illumination of the specimen. Various optical and mechanical attachments may be added to facilitate the analysis of the information in the doubly enlarged image. See also Electron microscope; Fluorescence microscope; Interference microscope; Lens (optics); Optical microscope; Phase-contrast microscope; Reflecting microscope; X-ray microscope.

---

microscope

A device that produces a magnified image of objects too small to be seen with the naked eye. Such objects are thus called “microscopic.” The microscope is widely used in medicine and biology. Common microscopes use lens es; others, such as electron microscope s, scan an object with electron s, x-ray s, and other radiation besides ordinary visible light.

n

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

For more information on microscope, visit Britannica.com.

---

The ability to view things that are too small to be seen by the unaided eye is important in espionage and security. For example, the diagnosis of an infection often relies in part on the visual examination of the microorganism. Information about how the microbe reacts to certain staining methods (e.g, the bacterial Gram stain), the shape of the microbe, and the reaction of antibodies to the microbe all provide important clues as to the identity of the organism.

As well, microscopic examination of documents can reveal information that cannot otherwise be seen. The high magnification and analysis of the elements that make up a sample that is possible using specialized techniques of scanning and transmission electron microscopy can reveal the presence of material that is of suspicious origin (i.e., missile casing), or the presence of codes on a surface.

A microscope is the instrument that produces the highly magnified image of an object that is otherwise difficult or impossible to see with the unaided eye. A microscope is able to distinguish two objects from one another that could not be distinguished with the eye. The resolving power of a microscope is greater than that of the eye.

History of the microscope. In ancient and classical civilizations, people recognized the magnifying power of curved pieces of glass. By the year 1300, these early crude lenses were being used as corrective eyeglasses.

In the seventeenth century Robert Hooke published his observations of the microscopic examination of plant and animal tissues. Using a simple two-lens compound microscope, he was able to discern the cells in a thin section of cork. The most famous microbiologist was Antoni van Leeuwenhoek. Using a single-lens microscope that he designed, Leeuwenhoek described microorganisms in environments such as pond water. His were the first descriptions of bacteria and red blood cells.

By the mid-nineteenth century, refinements in lens grinding techniques had improved the design of light microscopes. Still, advancement was mostly by trial and error, rather than by a deliberate crafting of a specific design of lens. It was Ernst Abbe who first applied physical principles to lens design. Abbe combined glasses that bent light beams to different extents into a single lens, reducing the distortion of the image.

The resolution of the light microscope is limited by the wavelength of visible light. To resolve objects that are closer together, the illuminating wavelength needs to be smaller. The adaptation of electrons for use in microscopes provided the increased resolution.

In the mid-1920s, Louis de Broglie suggested that electrons, as well as other particles, should exhibit wavelike properties similar to light. Experiments on electron beams a few years later confirmed this hypothesis. This was exploited in the 1930s in the development of the electron microscope.

Electron microscopy. There are two types of electron microscope. They are the transmission electron microscope (TEM) and the scanning electron microscope (SEM). The TEM transmits electrons through a sample that has been cut so that it is only a few molecules thin. Indeed, the sample is so thin that the electrons have enough energy to pass right through some regions of the sample. In other regions, where metals that were added to the sample have bound to sample molecules, the electrons either do not pass through as easily, or are restricted from passing through altogether. The different behaviors of the electrons are detected on special film that is positioned on the opposite side of the sample from the electron source.

The combination of the resolving power of the electrons, and the image magnification that can be subsequently obtained in the darkroom during the development of the film, produces a total magnification that can be in the millions.

Because TEM uses slices of a sample, it reveals internal details of a sample. In SEM, the electrons do not penetrate the sample. Rather, the sample is coated with gold, which causes the electrons to bounce off of the surface of the sample. The electron beam is scanned in a back and forth motion parallel to the sample surface. A detector captures the electrons that have bounced off the surface, and the pattern of deflection is used to assemble a three dimensional image of the sample surface.

Scanning, tunneling, and other microscopy techniques. In the early 1980s, the technique called scanning tunneling microscopy (STM) was invented. STM does not use visible light or electrons to produce a magnified image. Instead, a small metal tip is held very close to the surface of a sample and a tiny electric current is measured as the tip passes over the atoms on the surface. When a metal tip is brought close to the sample surface, the electrons that surround the atoms on the surface can actually "tunnel through" the air gap and produce a current through the tip. The current of electrons that tunnels through the air gap is dependent on the width of the gap. Thus, the current will rise and fall as the tip encounters different atoms on the surface. This current is then amplified and fed into a computer to produce a three dimensional image of the atoms on the surface.

Without the need for complicated magnetic lenses and electron beams, the STM is far less complex than the electron microscope. The tiny tunneling current can be simply amplified through electronic circuitry much like that used in other equipment, such as a stereo. In addition, the sample preparation is usually less tedious. Many samples can be imaged in air with essentially no preparation. For more sensitive samples that react with air, imaging is done in vacuum. A requirement for the STM is that the samples be electrically conductive.

Scanning tunneling microscopes can be used as tools to physically manipulate atoms on a surface. This holds out the possibility that specific areas of a sample surface can be changed.

Other forces have been adapted for use as magnifying sources. These include acoustic microscopy, which involves the reflection of sound waves off a specimen; xray microscopy, which involves the transmission of x rays through the specimen; near field optical microscopy, which involves shining light through an opening smaller than the wavelength of light; and atomic force microscopy, which is similar to scanning tunneling microscopy but can be applied to materials that are not electrically conductive, such as quartz.

Further Reading

Books

Aebi, Engel. Atlas of Microscopy Techniques. San Diego: Plenum Press, 2002.

Hayat, M. Arif. Microscopy, Immunohistochemistry, and Antigen Retrieval Methods for Light and Electron Microscopy. New York: Plenum Publishing, 2002.

Murphy, Douglas, B. Fundamentals of Light Microscopy and Electronic Imaging. New York: Wiley-Liss, 2001.

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

• acoustic m. — 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 m. — one with two eyepieces, permitting use of both eyes simultaneously.
• bright-field m. — the standard bench microscope used in histology and requiring stained tissue sections.
• compound m. — 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 m. — 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 m. — 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 m. — 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 m. — a microscope similar to the phase contrast microscope but delivers a three-dimensional image. Called also Nomarski interference phase microscope.
• light m. — 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 m. — one designed for use in performance of delicate surgical procedures, e.g. on the middle ear, eye or small vessels of the heart.
• phase m., phase-contrast m. — 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 m. — based on the phenomenon of birefringence; useful in the study of bone and muscle.
• scanning electron m. (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 m. — one that consists of a single lens.
• specular m. — one used in the examination of the corneal endothelium.
• stereoscopic m. — a binocular microscope modified to give a three-dimensional view of the specimen.
• surgical m. — see operating microscope (above).
• transmission electron m., 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 m. — uses an ultraviolet light source; useful in histochemical studies; only photographic images are available.

Dreaming about a microscope can be a message that we should look at something more carefully. Alternatively, it can represent the feeling that someone else is examining us in detail.

---

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - mikroskop

idioms:

• under the microscope    under mikroskopet

Nederlands (Dutch)
microscoop

Français (French)
n. - microscope

idioms:

• under the microscope    (lit, fig) au microscope

Deutsch (German)
n. - Mikroskop

idioms:

• under the microscope    unter der Lupe

Ελληνική (Greek)
n. - μικροσκόπιο

idioms:

• under the microscope    κάτω από το μικροσκόπιο

Italiano (Italian)
microscopio

idioms:

• under the microscope    al microscopio, sotto stretto controllo

Português (Portuguese)
n. - microscópio (m)

idioms:

• under the microscope    sob investigação detalhada (m) (fig.)

Русский (Russian)
микроскоп

idioms:

• under the microscope    под микроскопом

Español (Spanish)
n. - microscopio

idioms:

• under the microscope    investigar a fondo, examinar detenidamente

Svenska (Swedish)
n. - mikroskop

中文（简体）(Chinese (Simplified))
显微镜

idioms:

• under the microscope    在显微镜下, 仔细查看

中文（繁體）(Chinese (Traditional))
n. - 顯微鏡

idioms:

• under the microscope    在顯微鏡下, 仔細查看

한국어 (Korean)
n. - 현미경

idioms:

• under the microscope    세밀하게 조사하다

日本語 (Japanese)
n. - 顕微鏡

العربيه (Arabic)
‏(الاسم) مجهر‏

עברית (Hebrew)
n. - ‮מיקרוסקופ‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.

microscope	Swift Microscope
Digital Microscope	Flourescent Microscope