| 摘要 |
PURPOSE:To vary the depth of field and perform digital control by arranging plural annular liquid crystal cells of different size around one liquid crystal cell and controlling respective cells individually and electrically. CONSTITUTION:The annular liquid crystal cells 1b-1e of different size are arranged around the liquid crystal cell 1a. Namely, two circular transparent plates 2 and 2 are arranged opposite each other across a specific interval and a liquid crystal layer 3 is arranged between the transparent plates 2 and 2, but five couples of transparent electrodes 4a-4e corresponding to the cells 1a-1e are formed on internal surfaces of the transparent plates 2 and 2 concentrically so that they are controlled individually and electrically. Consequently, optional liquid crystal cells are made opaque to obtain a necessary aperture and liquid crystal cells which are positioned inside are made opaque successively from the external liquid crystal cell 1e to reduce the quantity of incident light and also increase the depth of field. Further, the respective cells are controlled with a digital signal, so no D-A converter, etc., are not necessary.
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