| 摘要 |
An observation system having a positive refracting power as a whole comprises a first unit G1 with a positive refracting power and a second unit G2 and forms an exit pupil for observation of an electronic image displayed on an image display element 5. The first unit G1 comprises a prism 4 with a positive refracting power and a transmission-type volume hologram 6 and has an action of imaging an observation image for obtaining a relay image. The second unit G2 is composed of a reflection-type volume hologram 3 and has an action of forming the exit pupil 1 so as to introduce the relay image to an observer. At least one of reflecting surfaces and an exit surface of the prism 4 is shaped as a rotationally asymmetric surface which exerts a power on bundles of rays, to compensate aberrations generated by decentering. Whereby, the observation optical system can be made so compact as to be applicable to an image display apparatus for cellular phones or portable intelligent terminals, and provides a bright view of an electronic image and a see-through image with high definition.
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