| 摘要 |
<p>When a laser beam is deflected by a mirror onto the surface of a workpiece, the angular movement of the mirror alters its distance from the piece, and therefore the beam is not always correctly focussed. In the invention, a focusing lens is located between a laser and the mirror; and the lens is moved towards or away from the mirror in accordance with the X-Y deflection of the latter. A suitable motor, e.g. a linear motor is pref. employed to move the lens towards or away from the mirror. The laser beam is always exactly focussed on the surface of the workpiece.</p> |
