| 摘要 |
PURPOSE:To improve the productivity and the reliability by a simple constitution by inserting parallel plates between a semiconductor laser and a beam splitter or between the beam splitter and a photodetector, and controlling a convergent state of a light beam. CONSTITUTION:A rough adjustment is executed so that the center of a photodetector 13 coincides roughly with an optical axis in a state that a plate 14 is not inserted, and a precise adjustment is executed in a state that a focus control is executed. Subsequently, a focus offset obtained from an output of the element 13 is measured, and one piece of plate 14 among plates 14a - 14c, etc. of such thickness as its value is brought close to zero is selected, inserted into a divergent light 15 extending from a semiconductor laser 11 to a beam splitter 12 or a convergent light extending from the splitter 12 to the element 13 and fixed. In such a way, the focus offset is brought close to zero, a concave lens becomes unnecessary, and the productivity and the reliability are improved by a simple constitution. |
