PURPOSE: To obtain a stereoscopic color picture through a small set by disposing a mirror device in a rectangular parallelopiped space enclosed by phase plates of three video tubes so that two dichroic mirrors can be at 45° with respect to an optical axis.

CONSTITUTION: A dichroic mirror 22 for red reflection and dichroic mirror 23 for blue reflection are intersected in an X shape and disposed in a rectangular parallelopiped space enclosed by phase plates of video tubes 19, 20 and 21, while on an optical axis of the green video tube 20 a projection lens 24 is arranged. In terms of the red reflection dichroic mirror 22, the red video tube 19 and green video tube 20 are in the mirror image relation, while in terms of the blue reflection dichroic mirror 23, the blue video tube 21 and green video tube 20 are in the mirror image relation. Monochromatic pictures projected on the video tubes 19, 20 and 21 are synthesized to a color picture by two dichroic mirrors, and enlarged and projected on a lenticular screen (not shown in the figure) by the magnification lens 24.