Patent ID: 6636356
Filing Date: 2003-10-21
Classification: G02B

Abstract:
An observation optical system which forms an exit pupil for observation of an electronic image displayed on an image display element and which has a positive refracting power as a whole, comprising:a first unit having a positive refracting power; and a second unit; wherein said first unit comprises at least one prism member having a positive refracting power; and said second unit comprises a diffraction element having a lens function caused by diffraction, wherein said first unit has an action of imaging the electronic image for obtaining a relay image, said second unit has an action for forming the exit pupil for introducing the relay image into an observer, said prism member has: an entrance surface via which bundles of rays emergent from the image display element enter said prism member; at least one reflecting surface on which the bundles of rays reflect inside said prism member; and an exit surface via which the bundles of rays exit out of said prism member; at least one of said reflecting surface and said exit surface is shaped as a curved surface which exerts a power on the bundles of rays, said curved surface being a rotationally asymmetric surface constructed and arranged to compensate aberrations caused by determining.