| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress harmful stray lights caused in an optical beam transmission adjusting means for adjusting the light power of a light beam without causing enlargement of mechanism. <P>SOLUTION: A holder holding a first transmitting element and a second transmitting element of an optical beam transmission adjusting means has constitution, where when an angle between a first reference plane and the first transmitting element is denoted as θ1 and an angle between the first reference plane and a second reference plane is denoted as θ2, θ1 and θ2 are calculated by using expression 1 and expression 2 from a second transmitting element angle θ3 at which harmful stray light is not produced by reflection of the second transmitting element when the light beam is, at a first position where the light beam is transmitted through the first transmitting element and from a first transmitting element angle θ4, at which effective luminous flux is not shielded by the first transmitting element, when the light beam is at a second position where the light beam transmits the second transmitting element. Expression 1 is θ1=(θ3+θ4)/2, and expression 2 is θ2=(180°+θ3-θ4)/2. <P>COPYRIGHT: (C)2008,JPO&INPIT |
