| 摘要 |
PURPOSE:To reduce the insensitive zones of the surface of a running body to be inspected by irradiating a single scanning mirror with a plurality of optical beams to generate a plurality of scanning optical beams having coherent characteristics. CONSTITUTION:As a scanning mirror 2, there are used both an electromagnetic vibratory mirror which is made vibratory by exerting the magnetic field to the mirror 2 magnetized and a rotary polygonal mirror in which mirrors on polygonal sides are turned by a motor. If a plurality of optical beams, e.g., two beams 2a and 2b are guided at a relative angle theta into the scanning mirror 2, those two beams are reflected on the scanning mirror so that the reflected beams 21a and 21b go into the surface of a running sample 1. The beams are then converted on the sample 1 into scanning beams 20a and 20b which are spaced at a preset distance l in the running direction. If the relative angle theta is suitably selected taking the running speed of the sample 1 into consideration, it is possible to obtain the desired scanning beam l. Thus, it is possible to minimize the insensitive zone. |
