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Opticians Glossary Of Terms (Test Question With Correct Solutions)
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Opticians Glossary Of Terms (Test Question With Correct Solutions)
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Opticians Glossary Of Terms (Test Question WithCorrect Solutions)
"A" measurement Right Ans - The horizontal dimension of the boxing
system rectangle that encloses a lens or lens opening.
Abbe value Right Ans - The most commonly used number for identifying
the amount of chromatic aberration for a given lens material. The higher the
Abbe value, the less chromatic aberration present in the lens. Abbe value is
the reciprocal of dispersive power and is symbolized by the Greek letter nu, or
v. Synonyms: nu value, constringence.
Aberration Right Ans - the resulting degradation of an image that occurs
when a point source of light does not result in a single-point image after going
through the lens or lens system.
Absolute refractive index Right Ans - the ratio of the speed of light in a
vacuum to the speed of light in another medium. "formula = speed of light in a
vaccum / speed of light in medium = absolute index of refraction".
Actual power Right Ans - Synonym for true power.
Near addition Right Ans - The power that a lens segment has in addition to
that power already present in the main portion of the lens.
Horizontal alignment Right Ans - A lack of deviation of the two datum lines
in a pair of spectacles from a single horizontal plane (neither lens higher than
the other when viewed from the front).
Standard alignment Right Ans - An impersonal standard, independent of
facial shape, for the alignment of spectacle frames. ie: "Four Point Touch"
Vertical alignment Right Ans - Lack of deviation of lenses from the vertical
plane (one being neither further forward nor backward than the other).
Vertex power allowance Right Ans - The amount by which the front surface
curvature of a lens must be flattened to compensate for a thickness-related
gain in power.
,Amethyst Contrast Enhancer (ACE) Right Ans - A selectively absorbing
glass developed by Schott said to enhance contrast and be advantageous for
target and trap shooting, hunting, computer terminal viewing, skiing, and bird
watching. The lens allows highest transmission in the blue, green, and red
regions of the spectrum.
Apical angle Right Ans - The angle formed by the junction of two
nonparallel prism surfaces.
Crest angle Right Ans - The angle from the top of the nose between the eyes
to the tip compared with the vertical plane of the face. (Because the line from
the top of the nose to the tip is not always straight, the area where the bridge
of the frame rests will become the frame of reference.)
frontal angle Right Ans - (1) The angle with which each side of the nose
deviates from the vertical. (2) The angular amount the nosepad face deviates
from the vertical when the frame is viewed from the front.
Pantoscopic angle Right Ans - (1) In standard alignment, that angle by
which the frame front deviates from the vertical (lover rims farther inward
than upper rims) when the spectacles are held with the temples horizontal.
(2) In fitting, the angle that the frame front makes with the frontal plane of the
wearer's face when the lower rims are closer to the face than the upper rims.
Antonym: retroscopic angle; synonym: pantoscopic tilt.
Retroscopic angle Right Ans - The angle that the frame front makes with
the frontal plane of the wearer's face when the lower rims are farther from the
face than the upper rims.
Antonym: pantosopic angle; synonym: retroscopic tilt.
Splay angle Right Ans - (1) The angle formed by the side of the nose with a
straight anterior-posterior surface that would bisect it vertically (also called
transverse angle)/ (2) The angle the face of a nosepad makes with a plane
perpendicular to that of the frame front when viewed from above.
Temple fold angle Right Ans - The angle formed when a temple is folded to
a closed position.
, Vertical angle Right Ans - When viewed from the side, that angle formed
between the plane of the lenses and the long axis of the adjustable nosepads.
Angle of deviation Right Ans - The difference between the angle of
incidence and the angle of refraction.
Anisometropia Right Ans - A condition in which one eye differs
significantly in refractive power form the other.
ANSI Right Ans - American National Standards Institute
Aperture Right Ans - (1) An opening or hole that admits only a portion of
light from a given source or sources. (2) The central, optically correct portion
of a lenticular lens.
Lens aperture Right Ans - The portion of the spectacle frame that accepts
the lens.
Synonym: lens opening.
Apex Right Ans - The junction point at which the two nonparallel surfaces
of a prism meet.
Aphakic Right Ans - A person or eye whose crystalline lens has been
removed.
AR Right Ans - Antireflection coating
Arm Right Ans - In a semirimless mounting, the metal reinforcement that
follows the upper posterior surface of a spectacle lens and joins the
centerpiece to the endpiece.
Synonyms: bar, browbar.
Guard arm Right Ans - A synonym for pad arm.
Pad arm Right Ans - A metal piece that connects an adjustable nosepad to
the front of a frame.
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