A high-efficiency, compact color illuminating system and a projection type
image display apparatus using the color illuminating system are provided.
The color illuminating system includes a light source, a spiral lens disc
that periodically scrolls light by rotational movement, and an optical
unit that isolates light beams of different wavelengths from white light
emitted from the light source and guides the isolated light beams to
enter at least two effective regions of the spiral lens disc. The
projection type image display apparatus includes the color illuminating
system, an image forming unit that generates images using scrolling light
from the spiral lens disc, and a projection lens unit that enlarges and
projects the images formed by the image forming unit on a screen.