| 摘要 |
PURPOSE:To suppress the aberration caused in a transmitted light by setting the length of the barrel in the direction of optical axis so as to satisfy the permissible tilt angle in the mounted accuracy with respect to the case so as to improve the stability of the barrel in the optical axis direction. CONSTITUTION:The titled device consists of a light source, an optical element 5 changing the converging or diverging state of a light beam radiated from the light source, the barrel 7 containing the optical element 5 and the case 3 fitted with the barrel 7, and the length (l) of the barrel 7 in the optical axis direction is set so that the permissible tilt angle Q of the optical element 5 in the optical axis direction in the accuracy of mount to the case 3 is satisfied. That is, the relation of l>=H/sin Q is satisfied, where H is a step of mount faces between the barrel and the case with respect to the length (l) of the barrel and Q(rad) is the permissible tilt angle of the optical element. Thus the barrel is made stable to the case in the direction of optical axis so as to suppress the aberration of the optical element. |
