2. A flat area set into a frame, attached to a handle, etc., for use in viewing oneself or as an ornament: Small framed hand mirrors were considered an appropriate courtship gift many years ago.
3. Any flat and shiny plane; such as, the surface of calm water under certain lighting conditions: The top level area of the lake was a perfect mirror, reflecting the rising moon and trees along the shores by the water.
4. Optics, an expansion that is either plane, concave, or convex and that sends back rays of light: Powerful telescopes use mirrors to gather the light rays in order to view the night skies.
5. Something that gives a minutely faithful representation, image, or idea of something else: The description of the grumpy old man in the story was a perfect mirror of Mark's unpleasant uncle who lived in an attic.
6. A pattern for imitation; exemplar: Henry was a man who was the mirror of self-discipline.
7. A glass, crystal, or the like, used by magicians, diviners, etc.: The fortune teller gazed into the mirror, fascinated by the light patterns, seeking to understand the predictions he felt were indicated there.
8. Etymology: from Old French mireor, "a reflecting glass," earlier miradoir (11th century), from mirer, "look at", from Vulgar (Common) Latin mirare, from Latin mirari, "to wonder at, to admire".
The most common use of mirrors is in the home for personal grooming, but mirrors are also used in scientific apparatus; such as, telescopes and lasers, and in industrial machinery.
Most mirrors are designed for visible light; however, mirrors designed for other wavelengths of electromagnetic radiation are also used, especially in optical instruments.
The history and development of mirrors
The mirror of the ancient Greeks and Romans was a disk of metal with a highly polished face, sometimes with a design on the back, and usually with a handle.
Glass mirrors date from the Middle Ages.
They were made in large numbers in Venice from the 16th century, the back being covered with a thin coating of tin mixed with mercury; after 1840, a thin coating of silver was generally substituted.
The introduction of plate glass for mirrors (17th century) stimulated the use of large stationary mirrors as part of household furniture.
Small bits of silvered glass were often used in the East to adorn articles of clothing and of decorations.
The metal trench hand mirror of World War I revived the manufacture of mirrors of this type. More recently, aluminum was introduced as the reflecting material because it is almost as efficient as silver but is more resistant to oxidation. Mirrors play an important part in the modern astronomical telescope.
Mirrors and telescopes
Telescopes and other precision instruments use front silvered mirrors, where the reflecting surface is placed on the front surface of the glass, which gives better image quality.
Some of them use silver, but most are aluminum, which is more reflective at short wavelengths than silver.
All of these coatings are easily damaged and require special handling. They reflect 90% to 95% of the incident light when new.
The coatings are typically applied by vacuum deposition. A protective overcoat is usually applied before the mirror is removed from the vacuum, because the coating otherwise begins to corrode as soon as it is exposed to oxygen and humidity in the air. Front silvered mirrors have to be resurfaced occasionally to keep their quality.
Mirrors have been a part of literature
- In Greek mythology, the hero Perseus killed Medusa by using a mirrored shield so as not to gaze directly upon her monstrous appearance.
- In English literature, a famous example is Lewis Carroll's Through the Looking Glass, in which protagonist Alice uses a mirror as a portal to a strange alternate world.
- Another example is found in the fairy tale Snow White, in which the Wicked Queen consults a magic mirror to determine the identity of the most beautiful woman in the world.
- In the Harry Potter novel, Philosopher's Stone, the "Mirror of Erised" is a magic mirror that reflects its viewer's deepest desires.
Also featured in the series is a type of device (a dark detector) that functions as a mirror, depicting not only the gazer but also a number of shadowy figures in the background who are enemies and their proximity to the viewer represents their imminent threat.
2. To show the image of something on a surface: It was easy to see the building being mirrored in the lake.
A computer programmer can mirror a process that exactly duplicates computer information from one location to another.3. In psychiatry, a technique in psychodrama in which another person in the group plays the role of the patient who is watching the enactment as if he or she were gazing into a mirror: The first person may exaggerate one or more aspects of the patient's behavior that was mirroring his or her actions.
Following the portrayal, the patient is usually encouraged to comment on what he or she has seen during the process as it was being mirrored.
2. A surface or a region capable of reflecting radio waves; such as, one of the ionized layers in the upper atmosphere.
2. An electrode that has the primary function of secondary emission of electrons.
It is used in multiplier phototubes and some types of television camera tubes.
2. A curved reflective surface, which may be either convex, bulging outwardly; or concave, bulging inwardly.
Most curved mirrors have surfaces which are shaped like part of a sphere, but other shapes are sometimes used in optical devices, too.