GB596096A - Improvements in or relating to optical scale-reading apparatus - Google Patents

Abstract

596,096. Measures of length. KAPELLA, Ltd., and CLIFFORD, T. W. July 18, 1945, No. 18434. Addition to 544,938, [Group XX]. [Class 106 (ii)] [Also in Group XX] A vernier apparatus for reading a scale and which may be applied to a linear dimension gauge as described in Specification 557,012, [Group XX], comprises a reference line on a movable graticule and substantially perpendicular to the length of the scale, and a pair of co-operating markings comprising a vernier scale substantially perpendicular to the length of the scale under observation and a second reference line substantially perpendicular to the vernier (one of the pair being fixed and the other on the graticule) substantially as described in the parent Specification and, for observing both scales and reference lines, a magnifying lens adjacent which is a stop narrow in the direction of the length of the scale and elongated in the direction perpendicular thereto, parallax being minimized by observation through the stop. As shown, the scale B is observed through an aperture E<1> in the stop E, the outer areas of which may be coloured or semitransparent, supported in a frame A carrying the lens D and having feet A<1> treating it on scale B. A graticule C movable at a slight angle transversely of the scale B by a micrometer screw (not shown) carries one or two vernier scales and a reference line, all of which are perpendicular to the length of the scale.