Abstract: To provide a highly practical rotary cutting tool with which chips can be satisfactorily removed even during longitudinal feeding, and the accumulation of chips can be minimized. A rotary cutting tool is provided, wherein a large number of helical chip-removing grooves (2) are provided in an external periphery of a distal end of a substantially cylindrical tool main body (1), and end cutting edges are provided at the lines of intersection between the cutting faces (3) of the chip-removing grooves (2) and the distal-end flanks of the tool main body (1); and at least one of the end cutting edges is configured so that the part of the cutting edge near the external periphery of the tool is recessed in the axial direction of the tool main body (1), forming a non-cutting part (22).

Abstract: A drill including a chisel edge provided at a tip end portion, a spiral first chip discharging groove and a spiral second chip discharging groove, land portions provided between the first chip discharging groove and the second chip discharging groove, and a cut blade provided at an edge of a rake surface of the first chip discharging groove, characterized in that the first chip discharging groove and the second chip discharging groove are provided asymmetrically with respect to a drill rotational center and a land portion behind the first chip discharging groove is larger than a land portion behind the second chip discharging groove.

Abstract: There is disclosed an optical measuring apparatus including a light scanning section for converting a light beam from a first light source to a parallel scanning light beam, a focussing section including a first focussing lens for focussing the parallel scanning light beam, an electric signal generating section for converting a focussed light to an electric signal, a measuring reference signal generating section and an electric signal processing section.The light scanning light section comprises a first mirror and a second mirror, each of which is rotated synchronously. The measuring reference comprises a transparent scale which is rotated in synchronism with the first and second mirrors, a light source, a second focussing lens and a second photoelectric conversion element. The electric signal processing section processes the electric signal from the electric signal generating section based on the measuring reference signal.