| 摘要 |
PURPOSE:To improve accuracy of positioning of a prism and form a case cheaply by placing the plane of emission of a prism on a fixed face of a case parallel to the incident optic axis and perpendicular to the optic axis of emission, and bringing the side face of the prism into contact with a wall face parallel to the incident optic axis and perpendicular to the fixed face. CONSTITUTION:The light receiving face of a bisected sensor 3 is parallel to the fixed face 2, and the division line 3a is positioned to conform respective output when emitted light 22 is at an ideal position, and becomes parallel to the X axis. The emitting face of a prism 1 is placed on the fixed face 2 formed in a case 6, and a side face of the prism 1 is brought into contact with a wall face 4. Thereby, positioning of the prism 1 in the directions of X axis and Z axis is made. Then, the prism 1 is made to emit light 22 from near the center of a through hole 5. The emitted light 22 is made to enter the bisected sensor 3. At such a time, each output of the bisected sensor is inputted to a subtracter circuit 11 to find the difference. When output of the subtractor circuit 11 is not zero, a shift controlling circuit 13 drives a shifting means 14. The shifting means 14 shifts the prism 1 while keeping the prism 1 in contact with the fixed face 2 and wall face 4 at high accuracy.
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