| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure irrespective of reflectivity by adjusting an irradiating luminance at each spot light or slit light corresponding to each detector having a pixel unit dimming mechanism. SOLUTION: A light linearly polarized by a polarizing plate 21 is incident to a liquid crystal 24. The crystal is a twisted nematic(TN) liquid crystal. The TN liquid crystal changes in a twisting amount of the crystal 24 in response to an electric field strength between opposed transparent electrodes 23 and 25 of the crystal 24. The light incident on the crystal 24 is turned in response to the twisting amount of the crystal 24, that is, turned in a polarizing direction of the linear polarization. A polarizing plate 28 is installed to become an orthogonal Nichol to the plate 21. When the electric field is not applied to the crystal 24, an incident linear polarization is turned at 90 degrees and passed through the plate 28. Since the polarization of the incident light on the plate 28 is changed by the field strength between the electrodes 23 and 25, a passing light amount of the plate 28 can be freely controlled. That is, a pixel unit dimming mechanism 6 can be realized by a liquid crystal display 6a.
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