Construction of mark direction detector


PURPOSE: To obtain a smaller measuring system, by arranging roughly parallel face to face located mirrors available for elongation in the longitudinal direction of a linear light-sensitive element between an observation opening and the linear light-sensitive element. CONSTITUTION: Two mirrors M 1 , M 2 are arranged roughly parallel and facing one to the other available for elongation in the longitudinal direction of a linear light sensitive element S between a cylindrical lens L and the linear light- sensitive element S. If these mirrors M 1 , M 2 were not arranged as is the conventional case, a beam of light emitted from a mark T would develop a linear image 1V vigorously offset from a position of the element S. However, if the M 1 and M 2 are arranged in this way, the bean after passing through the cylindrical lens L, repeats reflection over and over again until a linear image I is formed on the element S as is illustrated. Consequently, a X-direction position can be detected on the element S. This condition is applicable to a displacement of the mark T in the Y-direction. Limitation of detecting range in the direction perpendicular to X-Z plane is practically removed and a width of a mark direction detector of the linear light sensitive element in the vertical direction can pronouncedly be reduced. COPYRIGHT: (C)1987,JPO&Japio




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Patent Citations (1)

    Publication numberPublication dateAssigneeTitle
    JP-S51360-AJanuary 06, 1976Matsushita Electric Ind Co LtdShukorenzukei

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