FIELD: measurement technology. SUBSTANCE: applied instrument is predominantly intended for measurement of curvature radii of cylindrical surfaces of large-sized parts in heavy engineering industry. It includes case fitted with rotatable shoes resting with two contact members against measured surface. Case houses instrument converter coming in the form of two coordinate-sensitive photoelectric converters. Each of them is optically coupled to reflecting element anchored on turning axis of shoe located in opposition. Coupling is carried out by means of optical system in which semiconductor laser, collimating lens and splitting unit of prisms are integrated. Optical system is mounted between rotatable shoes. Reflecting element is manufactured in the form of prisms with right dihedral angles. Each coordinate sensitive photoelectric converter is connected to computer equipped with on-line storage and device with recorded computation program. Diffraction gratings are located between reflecting elements and focusing lenses. EFFECT: high sensitivity of instrument, reduced effect of roughness of surface. 1 cl, 6 dwg
