| 摘要 |
PURPOSE:To visually display the direction and quantity of center deviation so as to easily confirm the completion of adjustment, by adjusting the oriented position of a quartered sensor so that the light receiving output levels of areas facing to each other at both ends of an objective lens which is forcedly vibrated can be made equal to each other. CONSTITUTION:This invention utilizes a principle that, when the irradiated shape of a beam is completely extended in X-direction, the difference in light receiving output of an area provided in Y-direction becomes larger and the center deviation in Y-direction becomes distinct. Therefore, holding circuits 31 and 32 compare light receiving outputs of the 1st and 3rd areas 11a and 11c when the beam is completely extended in Y-direction. The 1st comparator circuit 37 which inputs the 1st and 2nd sample and hold outputs operates the 1st adjusting means 33 and adjust the position in Y-direction of a quartered sensor 11 by generating the 1st comparator output proportional to the center deviation in Y-direction and controlling the 1st driving circuit 39. The same operation is made for X-direction. A display means 41 which inputs both comparator outputs visually displays the direction and quantity of the center deviation and, therefore, completion of adjustment can be confirmed easily. |
