Illumination device, projection apparatus and projection-type image display apparatus

An illumination device comprising:

• an optical device including a hologram recording medium capable of reproducing an image of a reference member;
• and
• an irradiation unit including a scanning device to scan a coherent light beam on the hologram recording medium without controlling a beam diameter of the coherent light beam,
• wherein the irradiation unit comprises:
• a light source for emitting a coherent light beam so that the coherent light beam is scanned on the hologram recording medium, and wherein the light source comprises a plurality of light sources for emitting a plurality of coherent light beams having different wavelength ranges,
• wherein the hologram recording medium comprises a plurality of recording areas to be scanned with a plurality of coherent light beams reflected by the scanning device, and wherein each of the plurality of recording areas comprises an interference fringe that diffracts a coherent light beam of the corresponding wavelength range, and
• wherein the light source of the irradiation unit emits the coherent light beam so that each of the plurality of recording areas is incident with the coherent light beam having the corresponding one wavelength range and is not incident with the coherent light beam having another wavelength range, and
• wherein the optical device uses the plurality of coherent light beams reflected by interference fringes of the plurality of recording areas to reproduce the image of the reference member so that each of the coherent light beams is diffracted by each of the plurality of recording areas in the hologram recording medium and the diffracted coherent light beams are superimposed on an entire region of the illumination zone.