| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily compensate axial chromatic aberration of a projecting lens at a low cost by disposing a transparent plate capable of compensating the axial chromatic aberration of the projecting lens between a cross dichroic optical system and at least one optical modulation element. SOLUTION: Plane parallel glass plates 27, 28, and 29 having the same thickness (1 mm, for example) are inserted when the standard projecting lens 11 (intermediate focal point) is attached; however, when the forcal distance of the lens 11 is changed, the thickness of any one of the plates 27, 28, and 29 is changed, and property that optical path length is decreased in accordance with the increase of the thickness of the plates 27, 28, and 29 is utilized, so that the occurrence of the axial chromatic aberration caused when the focal distance of the projecting lens 11 is changed is prevented.</p> |
