| 摘要 |
PURPOSE:To obtain the optical attenuator which has a large attenuation quantity by combining a continuously variable attenuation filter and a stepwise variable attenuation filter with each other. CONSTITUTION:This optical attenuator is equipped with the continuously variable attenuation filter 1 using an attenuation filter which varies continuously in attenuation quantity and the stepwise variable attenuation filter 5 which uses an attenuation filter varying continuously in attenuation quantity and uses only the stepwise attenuation quantity part of the filter. Further, the attenuator is equipped with a control means 15 which performs control to a specific attenuation quantity state by the combination of both the filters 1 and 5 and also controls the relative rotating speed between both the filters 1 and 5 according to the ratio of the attenuation quantity distributions of the filters 1 and 5 and the ratio of the attenuation variation quantities at the point of time of the switching of the attenuation quantity of the filter 5 when the attenuation quantity is varied. An attenuation quantity set value obtained by an external input 16 and a rotary encoder 17 is inputted to a means 15, arithmetic for control over the filters 1 and 5 is performed at the part of the means 15, and D/A converters 18a and 18b drive driving motor 8a and 8b through driving circuits 19 and 20 to rotate. |
