| 摘要 |
PURPOSE:To prevent astigmatism of a projected image by making a pair of transparent plates nearly circular or elliptic through which projection light passes. CONSTITUTION:A polarization beam splitter 21 as a polarizing prism has a housing 22 in, for example, a rectangular parallelpiped at least one of their mutually opposite surfaces 22a and 22b is made of a transparent plate material. In this housing 22, a transparent flat plate 23 such as a glass plate which is made of a dielectric and has a multi-colored film with polarization characteristics formed on one surface is arranged on a diagonal line of the housing 22. Circular openings which are positioned concentrically are formed in the other pair of opposite surfaces 22c and 22d opposite each other across the flat plate 23. Then nearly circular or elliptic transparent plates 25a and 25b are fitted in the openings. Further, transparent liquid having nearly the same refractive index with the surfaces 22a and 22b and transparent plates 25a and 25b is charged in the housing 22 to constitute the polarization beam splitter 21. |
