Optical measuring apparatus for use on machines

摘要

PCT No. PCT/GB87/00470 Sec. 371 Date Mar. 1, 1988 Sec. 102(e) Date Mar. 1, 1988 PCT Filed Jul. 3, 1987 PCT Pub. No. WO88/00327 PCT Pub. Date Jan. 14, 1988.Optical apparatus for use with a machine having parts movable along three mutually orthogonal axes. The apparatus uses a single laser to direct a main beam along a first one of the axes and a square deflector mounted on a movable part of the machine to direct the beam orthogonally into a second direction without any angular errors due to pitch or yaw of the square deflector. Thus only roll of the square deflector need be measured. Further square deflectors are used to deflect the beam around other axes of the machine whereby the co-ordinates of a measuring probe can be accurately checked against the machine scale readings. Various methods of measuring roll are described including generating side beams from the main beam and directing them in anti-parallel direction to the main beam onto detectors which detect the deviation of the anti-parallel beams due to roll of the square deflector.