| 摘要 |
PURPOSE:To obtain a coherent optical image corresponding accurately to the input image of a space optical modulating tube by removing a DC optical bias due to natural double refraction with an easy operation. CONSTITUTION:An input image 1 is irradiated by an incoherent light source 10 and is projected to a photoelectric surface 31 of a space optical modulating tube 3 by a lens 2. The input optical image is converted to a photoelectronic image by the photoelectric surface 31 and is focused on the input surface of a microchannel plate 32 and is multiplied to form an electric charge image on the surface of a 55 deg. cut LiNbO3 single crystal plate 34. The light from a laser light source 4 is spread by an object lens 5 and has excess diffracted lights removed by a pinhole 6, and the polarization direction is fixed to a linear direction by a polarizer 7, and this light is converted to parallel light by a collimating lens 8 and passes a half mirror 9 and is made incident on the crystal plate 34 from the side of a face B. Refractive indexes in (x) and y' directions are different from each other in the crystal 34, and therefore, a phase difference is generated, and the light is outputted as an elliptically polarized light, and only the polarization direction is taken out, and a coherent optical image modulated by the input image 1 is obtained on a screen 12.
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