EYEPIECES

Noun

eyepieces

plural of eyepiece

Source: Wiktionary


EYEPIECE

Eye"piece`, n. (Opt.)

Definition: The lens, or combination of lenses, at the eye end of a telescope or other optical instrument, through which the image formed by the mirror or object glass is viewed. Collimating eyepiece. See under Collimate.

– Negative, or Huyghenian, eyepiece, an eyepiece consisting of two plano-convex lenses with their curved surfaces turned toward the object glass, and separated from each other by about half the sum of their focal distances, the image viewed by the eye being formed between the two lenses. it was devised by Huyghens, who applied it to the telescope. Campani applied it to the microscope, whence it is sometimes called Campani's eyepiece.

– Positive eyepiece, an eyepiece consisting of two plano-convex lenses placed with their curved surfaces toward each other, and separated by a distance somewhat less than the focal distance of the one nearest eye, the image of the object viewed being beyond both lenses; -- called also, from the name of the inventor, Ramsden's eyepiece.

– terrestrial, or Erecting eyepiece, an eyepiece used in telescopes for viewing terrestrial objects, consisting of three, or usually four, lenses, so arranged as to present the image of the object viewed in an erect position.

Source: Webster’s Unabridged Dictionary 1913 Edition



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Word of the Day

4 July 2024

CHLORTHALIDONE

(noun) a diuretic (trade names Hygroton and Thalidone) used to control hypertension and conditions that cause edema; effective in lowering blood pressure to prevent heart attacks


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Coffee Trivia

In 1884, Angelo Moriondo of Turin, Italy, demonstrated the first working example of an espresso machine.

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