Abstract: The invention relates to apparatus for measuring the dimensions of cylindrical objects by means of a scanning laser beam which is directed from a source (1) of laser light onto a rotating mirror (2) and through a first lens (6) located a focal-length distance from the center of rotation of the mirror. The beam is arranged to sweep over one side of the object (7) and is reflected onto the rotating mirror from where it is reflected onto a light detector (11) arranged to control a data processor (12), which determines and indicates the sensed dimension. The apparatus includes means (2,10,9,8) for directing the laser beam onto and to sweep the same over the other, opposite side of the object (7). During one revolution of the mirror the beam will therewith, during one half of a mirror revolution, sweep over a first side of the object, and will sweep over the other side of the object during the other half of the mirror revolution.

Abstract: A measuring device is disclosed which can measure an angle or length and which employs either an angle or length measuring plate. The angle or length measuring plate has thereon at least one measuring scale which has a regular pattern along the majority of the lengths thereof and an irregular pattern on two portions thereof. A light beam shines through an optical system to pass through the measuring scale at two points and from there into a photo-detector. The light path is arranged to pass through the two irregular portions at the same time. Several embodiments of the irregular patterns are shown. A circuit is also shown to detect the irregular portions and employ it as a reference signal.