Unusual Kinds of Mirrors
Other types of reflecting device are also called "mirrors".
- Acoustic mirrors are passive devices used to reflect and perhaps to focus sound waves. Acoustic mirrors were used for selective detection of sound waves, especially during World War II. They were used for detection of enemy aircraft prior to the development of radar. Acoustic mirrors are used for remote probing of the atmosphere; they can be used to form a narrow diffraction-limited beam. They can also be used for underwater imaging.
- Active mirrors are mirrors that amplify the light they reflect. They are used to make disk lasers. The amplification is typically over a narrow range of wavelengths, and requires an external source of power.
- Atomic mirrors are devices which reflect matter waves. Usually, atomic mirrors work at grazing incidence. Such mirrors can be used for atomic interferometry and atomic holography. It has been proposed that they can be used for non-destructive imaging systems with nanometer resolution.
- Cold mirrors are dielectric mirrors that reflect the entire visible light spectrum, while efficiently transmitting infrared wavelengths. These are the converse of hot mirrors.
- Corner reflectors use three flat mirrors to reflect light back towards its source. They are used for emergency location, and even laser ranging to the Moon.
- Hot mirrors reflect infrared light while allowing visible light to pass. These can be used to separate useful light from unneeded infrared to reduce heating of components in an optical device. They can also be used as dichroic beamsplitters. (Hot mirrors are the converse of cold mirrors.)
- Metallic reflectors are used to reflect infrared light (such as in space heaters or microwaves).
- Non-reversing mirrors are mirrors that provide a non-reversed image of their subjects.
- X-ray mirrors produce specular reflection of X-rays. All known types work only at angles near grazing incidence, and only a small fraction of the rays are reflected. See also X-ray optics.
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Famous quotes containing the words unusual, kinds and/or mirrors:
“In proceeding to the dining-room, the gentleman gives one arm to the lady he escorts—it is unusual to offer both.”
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)
“There are two kinds of fathers in traditional households: the fathers of sons and the fathers of daughters. These two kinds of fathers sometimes co-exist in one and the same man. For instance, Daughter’s Father kisses his little girl goodnight, strokes her hair, hugs her warmly, then goes into the next room where he becomes Son’s Father, who says in a hearty voice, perhaps with a light punch on the boy’s shoulder: “Goodnight, Son, see ya in the morning.””
—Letty Cottin Pogrebin (20th century)
“Our age is very cheap and intelligible. Unroof any house, and you shall find it. The well-being consists in having a sufficiency of coffee and toast, with a daily newspaper; a well glazed parlor, with marbles, mirrors and centre-table; and the excitement of a few parties and a few rides in a year.”
—Ralph Waldo Emerson (1803–1882)