| 摘要 |
Filter than can be adjusted to transmit varying amounts of light, and characterized by uniform degree of transparence over its entire working portion. One embodiment of said filter includes an elongated, flexible, semi-transparent strip (10) having a linearly varying degree of transparence, a pair of reels (14 and 16) around which the ends of the strips are wound, and three of roller bearings (18, 20 and 22) for supporting the strip in a doubled over manner between a light source (30) and a target surface (32). A knob (24) is adjusted to align different portions of the doubled over strip and thus vary the composite degree of transparence of the filter. |
