PURPOSE: To form an image from a projecting cathode-ray tube on a screen with accuracy by arranging at least one of combined lenses while it will slant to the surface perpendicular to the optical axis in the opposite direction to that of the screen.

CONSTITUTION: One lens 2' in combined-lens part 2 and screen 3 are arranged slanting to the surface perpendicular to the optical axis of cathode-ray tube 1 and combined lenses 2 in the mutually-opposite directions respectively. Thus, the image- formation surface by combined lenses 2 can be made to nearly agree with the inclination of screen 3 as shown by the dotted line.