iew for explanation of specific fixation of the color separation system, the light modulation part, etc.;FIG. 4 is a side view for explanation of the structure of a lens 45b;FIGS. 5A and 5B are a plan view and a side view for explanation of mounting of the lens;FIGS. 6A to 6D are diagrams for explanation of a position changing method of the lens;FIG. 7 is a plan view for explanation of mounting of