Illumination device comprising a first phase difference layer disposed adjacent to a second phase difference layer in a same layer on a main surface of a liquid crystal element

An illumination device comprising:

• a light source;
• a first liquid crystal element opposed to the light source;
• a second liquid crystal element opposed to the first liquid crystal element and having a first region and a second region;
• a first phase difference layer opposed to the second liquid crystal element;
• and
• a second phase difference layer opposed to the second liquid crystal element and adjacent to the first phase difference layer,
• wherein the first liquid crystal element diffracts first circularly polarized light out of emitted light from the light source toward the first region, and diffracts second circularly polarized light rotating reversely to the first circularly polarized light toward the second region,
• in the first region, the second liquid crystal element converts first circularly polarized light into second circularly polarized light and diffracts the second circularly polarized light toward the first phase difference layer, and in the second region, the second liquid crystal element converts second circularly polarized light into first circularly polarized light and diffracts the first circularly polarized light toward the second phase difference layer,
• the first phase difference layer converts second circularly polarized light into linearly polarized light,
• the second phase difference layer converts first circularly polarized light into linearly polarized light, and
• a polarization direction of linearly polarized light that is transmitted light through the first phase difference layer is substantially parallel to a polarization direction of linearly polarized light that is transmitted light through the second phase difference layer.