Optical mirror and optical scanner and laser machining apparatus using the same

The present invention relates to a rapidly rotatable optical mirror, and an optical scanner and a laser machining apparatus employing the improved mirror. A reliable galvano-mirror employed for laser machining is disclosed. The mirror is far reduced its weight for getting a higher rotation. On the rear surface of the mirror, a lightweight rib-structure, which is formed from a mirror support beam centered across the surface and some ribs extending from the beam, holds the mirror. Against a distortion occurred in rotating at high speed, the mirror is provided with a high rigidity. And the mirror is structured integrally with the motor shaft holder. Besides, a slit is formed between the rib disposed close to the holder and the support beam centered across the rear surface of the mirror. Providing slit enables to minimize a local distortion caused by a stress from fastening screws to attach the mirror to the motor shaft.