| 摘要 |
The invention relates to a slimmed-down yet high-performance image display device which comprises a decentered prism capable of internal reflection and a reflection type image display device such as a reflection-type LCD or DMD and can present bright images to an observer, and provides an image display apparatus comprising a light source 5, a reflection type image display device 3, and an ocular optical system for guiding an image displayed on device 3 into an eyeball position for forming an intermediate image 4. The ocular optical system comprises a prism member 10 comprising an entrance surface 11 and two reflecting surfaces 12 and 13. In a prism, an optical path for connecting the first surface 11 with the second surface 12 intersects a reflecting optical path from the third surface 13. The ocular optical system further comprises a back-coated reflecting surface 23 between the third surface 13 and an observer's eyeball side. The first surface 11, second surface 12 and third surface 13 are located between the image display device 3 and the intermediate image 4. The second surface 12, third surface 13 and back-coated reflecting surface 23 are each formed into a rotationally asymmetric surface shape capable of imparting power to a light beam and making correction for decentration aberrations. Illumination light is incident from the third surface 13 on the image display device 3 to illuminate the same.
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