| 摘要 |
PROBLEM TO BE SOLVED: To provide an image display device where flare light (unnecessary diffracted light) generated from a diffraction optical element is hardly recognized by an observer. SOLUTION: The image display device includes a display element 1 displaying an original picture, and an optical system OS guiding light from the display element to an exit pupil. The optical system includes the diffraction optical element 3. An axis leading to the center of the exit pupil from the center of a display area of the original picture on the display element is defined as an optical axis AXL of the optical system, a point on the diffraction optical element is defined as P, and a diffracted light beam having specified wavelength and specified diffraction order where scalar diffraction efficiency is the highest out of diffracted light beams from the point P is defined as a specified diffracted light beam. At such a time, the shape of a grating to which the point P belongs on the diffraction optical element is set so that the specified diffracted light beam may turn to a predetermined point more separate from the diffraction optical element than the exit pupil on the optical axis. COPYRIGHT: (C)2009,JPO&INPIT
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