| 摘要 |
PURPOSE: To simplify the fabrication of a chart plate by disposing a pair of polar screens, which are put on top of each other with their respective polarizing axes forming an anale of 90 deg., and forming identically shaped chart holes, which are shifted as far as a parallax is produced in the pair of polar screens. CONSTITUTION: Identically shaped chart holes 14L and 14R, which are shifted by a distanceΔto produce a parallax, are respectively formed as a polarizing pattern in a pair of polar screens 12L and 12R. A part i, where both holes are put on each other, does not transmit light from a lamp 11, and therefore, looks dark. Light transmit a part ii where the polar screen 12R faces the chart hole 14L. Respective light beams transmitted through the parts ii and iii differ from each other by 90 deg. in polarizing direction, and simultaneously, are made respectively equal to the polar screens 13L and 13R in polarizing direction. The light beam transmitted through the part iii of the polar screen 12L is visually confirmed through the polar screen 13L by the left eye EL of an inspectee. The light beam transmitted through the shifted part of the polar screen 12R is visually confirmed through the polar screen 13R through the right eye ER of the inspectee.
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