| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a variable optical filter wherein a periodic filter characteristic can be subjected to parallel displacement over a wide range in the direction of an optical frequency axis without substantially changing light intensity. <P>SOLUTION: This variable optical filter 1 comprises first and second filter units 11, 12 connected in series on an optical path 13, and a control unit 14 for controlling the periodic filter characteristic of each filter unit. The control unit 14 controls each filter characteristic of the first and the second filter units 11, 12, relatively, so that switching from one filter unit to the other filter unit is carried out on condition that the filter characteristic of the variable optical filter 1 is kept constant as a whole, when parallel displacement beyond the variable range in the direction of the optical frequency axis is required as to one of the first and the second filter units 11, 12. <P>COPYRIGHT: (C)2004,JPO |
