cone of light


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cone

 [kōn]
1. a solid figure or body having a circular base and tapering to a point.
2. one of the conelike structures which, with the rods, form the light-sensitive elements of the retina; the cones make possible the perception of color. See also eye and vision. Called also retinal cone.
3. in radiology, a conical or open-ended cylindrical structure formerly used as an aid in centering the radiation beam and as a guide to source-to-film distance. Cones were commonly attached to the x-ray tube prior to the use of the collimator.
4. in root canal therapy, a solid substance with a tapered form, usually made of gutta-percha or silver, fashioned to conform to the shape of a root canal.
ether cone a cone-shaped device used over the face in administration of ether for anesthesia.
gutta-percha cone in root canal therapy, a plastic radiopaque cone made from gutta-percha and other ingredients, available in standard sizes according to the dimensions of root canal reamers and files; used to fill and seal the canal along with sealer cements. Called also gutta-percha point.
cone of light the triangular reflection of light seen on the tympanic membrane.
pressure cone the area of compression exerted by a mass in the brain, as in transtentorial herniation.
retinal cone cone (def. 2).
silver cone silver point.

light re·flex

1. Synonym(s): pupillary reflex
2. a red glow reflected from the fundus of the eye when a light is cast on the retina, as in retinoscopy; Synonym(s): eye reflex, fundus reflex
3. a triangular area at the anterior inferior part of the tympanic membrane, extending from the umbo to the periphery, where there is seen a reflection of light. Synonym(s): cone of light, Politzer luminous cone, pyramid of light, red reflex, Wilde triangle

red re·flex

(red rē'fleks)
Term describing reflection of light from retina in healthy eyes; abnormality in ocular media, refractive state, or retina can cause this reflex to be abnormal.
Synonym(s): cone of light, light reflex (3) , pyramid of light.
References in periodicals archive ?
today after school the teepee was covered with loose canvas and tonight it is a cone of light golden, in the groin of the hill
But a quite different picture emerges when one peeks outside the small cone of light cast by the trade press.
But people working round the cone of light are not left entirely without knowledge of the elements, for those eye-browed strips of glazing that give the outside its brooding presence turn out to be clerestories that bring light in over the bookstacks; the brows serve to reduce glare and prevent direct sunlight from striking the books.
Forty-foot-tall cone of light turns the Space Needle into the world's tallest Christmas tree stand.
The TIR optic also interacts with all of the light from the LED, whereas there is typically a large cone of light from a traditional, reflector-based luminaire (a.k.a.
There is gratification in instantly "getting it," in feeling a piece work its magic--something Dan Graham must have felt in the photograph screenprinted on Chapter 12: iamb (blind smile), 2008, in which the blissed-out artist bathes in a cone of light.
A cone of light, perhaps 30[degrees] wide at the base under the best of skies, will be visible.
Cone of light which seemed a gesture urgently made by a speaker now far in the distance.
Old man in his cone of light, his juncture of past and future.
But after completing it, my attention pulled back from events in front of the camera and became engaged by the possibility of a film that could exist only in the moment of projection with an audience, without reference to an "elsewhere." The thirty-minute Line Describing a Cone, made soon after I moved to New York from London in 1973, took the form of the gradual coming-into-being in midair of a complete, hollow cone of light. The proportions of this projection vary, but the scale is large.