The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 11, 1993
Filed:
Feb. 11, 1992
Hiroshi Komazawa, Atsugi, JP;
Fuminobu Ito, Atsugi, JP;
Kenichiro Umesaki, Atsugi, JP;
Yuuichi Watanabe, Odawara, JP;
Yoshiharu Sasaki, Fujinomiya, JP;
Anritsu Corporation, Tokyo, JP;
Abstract
A first optical attenuation filter is arranged in a predetermined optical path and attenuates light to be attenuated with a first variable attenuation amount. A second optical attenuation filter is arranged in the predetermined optical path and attenuates, with a second variable attenuation amount, the light which has been transmitted through the first optical attenuation filter. The first and second optical attenuation filters can be driven in the forward and reverse directions and each has an attenuation amount characteristic which changes monotonously in both the forward and reverse directions. An attenuation amount setting section sets a desired attenuation amount to the light to be attenuated. First and second drivers are coupled to drive the first and second optical attenuation filters in the forward and reverse directions, respectively. A controller controls driving directions and driving amounts of the first and second optical attenuation filters through the first and second drivers in accordance with the desired attenuation amount so that an algebraic sum of the first and second attenuation amounts finally becomes equal to the desired attenuation amount and a variation in attenuation amount is decreased as a whole, thereby providing a smooth attenuation characteristic.