DE1900335

1,245,751. Mirror mountings. BRITISH OXYGEN CO. Ltd. Jan.1, 1969 [Jan.8, 1968], No.1101/68. Heading G2J. [Also in Division B3] In apparatus for heating, e.g. fusion welding or cutting, one or more workpieces 22 along a desired path by means of a beam of radient energy, the beam source, e.g. a continuous wave CO 2 laser 2, and the workpiece are stationary and the beam is directed from the source to the workpiece via a rotary first mirror 14 in line with said source and a movable second mirror 16 which traces out a path corresponding to the desired path. The latter may be a circular or non-circular path or part thereof. The mirrors are plane and front-surface coated. In Fig. 1, which arrangement provides for circular paths only, the mirror 14 is rigidly mounted on a support plate 6 which is rotatable about the axis of the laser 2 by a pinion 8 driven by an electric motor 10. The mirror 16 is fast with, or, for paths of different diameters, radially adjustably secured to, the plate 6. The beam 26 reflected from the mirror 16 is focused on the workpiece by a lens 22 fast with the mirror 16. In Fig.2, which arrangement provides for both circular and non-circular paths, the support plate 6 is fixed and the mirror 14 is rotatably mounted thereon by a roller or ball bearing 30. The mirror 16 is carried by the frame of an electric motor 32 which is radially movable on a rod 42 extending from the mounting of the mirror 14 outside the optical path between the mirrors. The motor 32 rotates a platform 36 on which is carried an electric motor 38 driving a wheel 40 frictionally engaging the plate 6. Preferably, the mirror 16 is so mounted that the beam therefrom lies in the plane containing the beams to and from the mirror 14. The beam from the mirror 16 may be oblique, but is preferably normal, to the workpiece. In operation, the motor 38 preferably rotates at a constant speed, and since the wheel 40, the shaft 34 of the motor 32 and the effective centre of the mirror 16 are arranged in line, the beam from the latter, when normal to the workpiece travels at the speed of the wheel 40. The motor 32, however, acts to steer the wheel 40 and its speed is adjustable, down to zero, to determine the desired path, such adjustment being controlled from magnetic or paper tape stored data, or by an associated line pattern follower which may comprise two co-ordinate motors controlling the motors 32, 38 directly.