| 摘要 |
PROBLEM TO BE SOLVED: To totally save electric power by continuously varying an optical attenuation amount and reducing a current value which needs to be always supplied to adjust the optical attenuation amount. SOLUTION: A polarizer 10 and an analyzer 12 are disposed between an input collimation system and an output collimation system, and a discrete variation type optical attenuating mechanism 14 having self-holding type Faraday rotators FR1 and FR2 and a continuous variation type optical attenuating mechanism 16 having a continuous power supply type Faraday rotors FR3 are arrayed between the polarizer and analyzer linearly along an optical axis. Switching control over a current direction to a magnetic field applying means of the self-holding type Faraday rotors and power supply control over a current value to a magnetic field applying means of the continuous power supply type Faraday rotor are combined with each other to interpolate a discrete optical attenuation amount by the discrete variation type optical attenuating mechanism with a continuous optical attenuation amount by the continuous variation type optical attenuating mechanism, thereby adjusting the optical attenuation amount in detail. COPYRIGHT: (C)2009,JPO&INPIT
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