Collimating eyepiece, an eyepiece with a diagonal reflector for illumination, used to determine the error of collimation in a transit instrument by observing the image of a cross wire reflected from mercury, and comparing its position in the field with that of the same wire seen directly.Collimating lens (Optics), a lens used for producing parallel rays of light.

Collimation
(Col`li*ma"tion) n. [Cf. F. collimation, fr. a false reading (collimare) for L. collineare to direct in a straight line; col- + linea line. Cf. Collineation.] The act of collimating; the adjustment of the line of the sights, as the axial line of the telescope of an instrument, into its proper position relative to the other parts of the instrument.

Error of collimation, the deviation of the line collimation of an astronomical instrument from the position it ought to have with respect to the axis of motion of the instrument.Line of collimation, the axial line of the telescope of an astronomical or geodetic instrument, or the line which passes through the optical center of the object glass and the intersection of the cross wires at its focus.

Collimator
(Col"li*ma`tor) n.

1. (Astron.) A telescope arranged and used to determine errors of collimation, both vertical and horizontal. Nichol.

2. (Optics) A tube having a convex lens at one end and at the other a small opening or slit which is at the principal focus of the lens, used for producing a beam of parallel rays; also, a lens so used.

2. (Logic) That process by which a number of isolated facts are brought under one conception, or summed up in a general proposition, as when Kepler discovered that the various observed positions of the planet Mars were points in an ellipse. "The colligation of facts." Whewell.

Colligation is not always induction, but induction is always colligation.
J. S. Mill.

Collimate
(Col"li*mate) v. t. [imp. & p. p. Collimated; p. p. & vb. n. Collimating.] [See Collimation.] (Physics & Astron.) To render parallel to a certain line or direction; to bring into the same line, as the axes of telescopes, etc.; to render parallel, as rays of light.

By PanEris using Melati.

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