| 摘要 |
PROBLEM TO BE SOLVED: To obtain high light-using efficiency and a perfect 0 level by providing a movable mirror which can deflect light in response to an applied voltage. SOLUTION: A reflecting light 5a is allowed to enter a pyroelectric body, while a reflecting light 5b is not allowed to enter the pyroelectric body. In this arrangement, the light is chopped by a movable mirror element. A deflection angleβbetween the reflecting lights 5a and 5b and a rotating angleαof the movable mirror 12 from a horizontal direction hold a relationβ=4α. On the other hand, the rotating angleαis determined by a length L of the movable mirror 12 and a gap light (h) between a lower end of the movable mirror 12 and bias electrodes 22a, 22b, which holds a relation sinα=2h/L. Accordingly, the deflection angleβis equal to 4 sin<-1> (2h/L). The gap length (h) should be increased or the length L of the movable mirror 12 should be reduced in order to enlarge the deflection angleβ.
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