DICT.TW Dictionary Taiwan

 Op·tic Op·tic·al a.
 1. Of, pertaining to, or using vision or sight; as, optical illusions. [wns=2]
 Syn: -- ocular, optic, visual.
 The moon, whose orb
 Through optic glass the Tuscan artist views.   --Milton.
 2. Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina; the optic (or optical) axis of the eye. See Illust. of Brain, and Eye. [wns=3]
 3. Relating to the science of optics or to devices designed to assist vision; as, optical works; optical equipment. [wns=1]
 Optic angle Opt., the angle included between the optic axes of the two eyes when directed to the same point; -- sometimes called binocular parallax.
 Optic axis. Opt. (a) A line drawn through the center of the eye perpendicular to its anterior and posterior surfaces.  In a normal eye it is in the direction of the optic axis that objects are most distinctly seen. (b) The line in a doubly refracting crystal, in the direction of which no double refraction occurs.  A uniaxial crystal has one such line, a biaxial crystal has two.
 Optical circle Opt., a graduated circle used for the measurement of angles in optical experiments.
 Optical square, a surveyor's instrument with reflectors for laying off right angles.
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