| 摘要 |
PURPOSE:To attain size reduction and an increase in switching speed by providing a holed plate on an optical axis and rotating this plate around an axis crossing the optical axis at right angles, and thus cutting off a light beam. CONSTITUTION:Light projected from an optical fiber 7a is converted by a rod lens 8a into a parallel light beam, which passes through a hole bored in the shield plate 11 and is converted by a rod lens 8b to enter an optical fiber 7b. When the outside temperature rises, spiral springs 12 and 13 which are made of shape memory alloy and installed in the same direction with the optical axis contact, so the shield plate 11 rotates around the axis crossing the optical axis at right angles to cut off the light beam, so no light beam is incident on the optical fiber 7b. Thus, the springs are provided in the same direction with the optical axis to reduce the size and heat capacity, thereby increasing the switching speed.
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