| 摘要 |
PURPOSE:To always detect stably the focus with a high precision by specifying the shape of a pattern projected from the camera side to the object side. CONSTITUTION:The pattern consists of a shape where the line thickness is increased in only one direction from the center part toward the peripheral part, a shape where the line thickness and line intervals are increased in only one direction from the center part to the peripheral part, and a shape of concentric circles where line intervals are increased according as going from the center part to the peripheral part. In each shape of the pattern, the line thickness or/and the line intervals are increased successively according as going from the center part to the peripheral part. That is, the space frequency of the pattern is reduced successively according as going from the center part to the peripheral part. Since the pattern of these shapes is constituted, properties of the pattern of a distance measuring object in the object side is not changed to perform distance measuring always with a uniform pattern even if any of photographic lenses from a telephoto lens to a wide angle lens is used.
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