| 摘要 |
PROBLEM TO BE SOLVED: To provide a new polarization illumination device having high light use efficiency, a simple structure, and high flexibility of a design of a polarization conversion element. SOLUTION: The polarization illumination device includes: a first light source emitting non-polarized light at a wavelengthλ1; a second light source emitting non-polarized light at a wavelengthλ2 (<λ1); and a polarization conversion optical system polarization-converting the light from the first and second light sources into polarization in the same direction, and making the light to nearly the same directions. The polarization conversion optical system includes: a polarization separating element 1-105 having a polarization separating layer 1-1050 on which the light from the first light source and the light from the second light source are incident at a prescribed angle:θfrom directions different from each other; a deflection means 1-106 converting one advance direction of the light separated by the polarization separating element into a direction parallel to the other advance direction; and a 1/2-wavelength plate 1-107 rotating a polarization direction of one of the light separated by the polarization separating element at 90 degrees. In the polarization separating layer, a laminate obtained by laminating materials having different refractive indexes on a board has a minute periodic structure in one direction, and has structural birefringence. COPYRIGHT: (C)2009,JPO&INPIT
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