| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an illumination optical system capable of extracting necessary reflected light from an object to be illuminated in a range small in distance from the object, and suitable for illumination of an image display device using a reflection type LCD or DMD as a spatial modulator. <P>SOLUTION: This illumination optical system is configured by including: a plate-like transparent base material having a diffraction grating on a surface thereof; and a diffraction grating element formed on the diffraction grating of the transparent base material, and having a separation coating for reflecting or transmitting incident light according to a characteristic of the incident light. In the illumination optical system, the object to be illuminated is illuminated by guiding light to the object by the diffraction grating element, and light reflected by the object is made to permeate the diffraction grating element, and guided to the outside. <P>COPYRIGHT: (C)2009,JPO&INPIT |
