Abstract: A method for inspecting defects inside a rod-shaped transparent object by using a scanning beam of parallel light rays directed onto a rod-shaped transparent object orthogonally to the longitudinal axis of the object so that an inspection plane comprises an object's cross-section. The scanning beam is detected at an opposite side of the rod-shaped object that is interposed to intercept the parallel rays of the scanning beam. The electric output signal from the detector is processed to produce a first light intensity profile in a first scan direction, the light intensity profile comprising a shadow region delimited by first and second shadow edges, which is indicative of the outside diameter of the object across the inspection plane.

Abstract: A method for inspecting defects inside a rod-shaped transparent object by using a scanning beam of parallel light rays directed onto a rod-shaped transparent object orthogonally to the longitudinal axis of the object so that an inspection plane comprises an object's cross-section. The scanning beam is detected at an opposite side of the rod-shaped object that is interposed to intercept the parallel rays of the scanning beam. The electric output signal from the detector is processed to produce a first light intensity profile in a first scan direction, the light intensity profile comprising a shadow region delimited by first and second shadow edges, which is indicative of the outside diameter of the object across the inspection plane.

Abstract: A method and a system based on the method imparts to an optical fiber a predetermined rotation about its axis, wherein the fiber is rotated by way of a frictional force acting on the fiber while it is advanced in a predetermined direction. The rotation actually imparted to the optical fiber is measured on-line while the fiber is advancing in the direction and the frictional force is controlled responsively to the measured rotation so as to obtain the predetermined rotation. Spinning devices acting on the optical fiber by way of an externally controllable frictional force and particularly suitable to be used with the method are disclosed.