| 摘要 |
PURPOSE:To continuously and quickly control the size of a light beam in a similar form by providing a continuously changing groove on the peripheral surface of a disk or a polygonal prism body and irradiating this groove with the light beam to change the size of the light beam. CONSTITUTION:A groove 2 whose width and depth are continuously changed is provided on the peripheral surface of a disk 1, and the disk 1 is rotated around a revolving shaft 3 to change a light beam 4 to an arbitrary size in a control position 5. For example, when the disk 1 is rotated clockwise, the size is successively changed to A to D in accordance with the form of the groove 2. In this case, the point D is the practical control reference point of the form formed by the groove 2, and the form of the groove 2 is expanded downward in a similar form with the control reference point as the center, and the center of the form is moved downward. If it is necessary to linearly arrange the center of the form, namely, the center of dots, the pulse intervals of the light beam or the angle or irradiation of the light beam is changed to correct the deviation of the center of the form. |
