| 摘要 |
An image display unit for forming the virtual image of an image display element to display an image, comprising a transmitting diffractive optical element (50) for diffracting an output light from an image display element (20), and a reflecting optical element (70) having a positive optical power to reflect a diffraction light from the transmitting diffractive optical element (50). The transmitting diffractive optical element (50) diffracts a light beam reflected by the reflecting optical element (70) and re-entering the transmitting diffractive optical element (50), with a diffraction efficiency smaller than a diffraction efficiency with which to diffract an output light from the image display element (20).
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