Category:Optic

Op"tic, n. Etym: [from optic, a.]

1. The organ of sight; an eye. The difference is as great between the optics seeing, as the object Seen. Pope.

2. An eyeglass. [obs.] Herbert.

Optic; optical Op"tic, op"tic*al, a. Etym: [f. optique, gr. oculus eye. See ocular, Eye, and cf. Canopy, ophthalmia.]

1. Of or pertaining to vision or sight. 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. See illust. of brain, and eye.

3. Relating to the science of optics; as, optical works. 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.