"Aperture" is a word in ENGLISH

To bring to a true relative position, as the parts of an instrument; to regulate for use; as, to adjust …

The operation of bringing all the parts of an instrument, as a microscope or telescope, into their proper relative position …

The portion of a graduated instrument, as a quadrant or astrolabe, carrying the sights or telescope, and showing the degrees …

To render larger, more extended, or more intense, and the like; -- used especially of telescopes, microscopes, etc.

A dioptric telescope, fitted with two tubes joining, so as to enable a person to view an object with both …

A binocular glass, whether opera glass, telescope, or microscope.

Adapted to the use of both eyes; as, a binocular microscope or telescope.

A concave tool used in grinding lenses or the speculums of telescopes.

An instrument for the accurate measurement of small differences of height; esp. of the differences in the height of the …

A reflecting telescope, part of which is made to rotate eccentrically, so as to produce a ringlike image of a …

To render parallel to a certain line or direction; to bring into the same line, as the axes of telescopes, …

The act of collimating; the adjustment of the line of the sights, as the axial line of the telescope of …

A telescope arranged and used to determine errors of collimation, both vertical and horizontal.

A telescope of low power, having a large field of view, used for finding comets.

The act of defining; determination of the limits; as, a telescope accurate in definition.

A plate with an opening, which is generally circular, used in instruments to cut off marginal portions of a beam …

Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a …

Having no disk; appearing as a point and not expanded into a disk, as the image of a faint star …

An instrument for determining the magnifying power of telescopes, consisting usually of a doubleimage micrometer applied to the eye end …

An instrument consisting of a telescope so mounted as to have two axes of motion at right angles to each …