Patent attributes
An image projection system according to the present disclosure includes a projection optical system and an eyepiece optical system. The projection optical system projects an image. The eyepiece optical system is configured separately from the projection optical system and is to be mounted on a head of a viewer. The eyepiece optical system includes at least one holographic element. The eyepiece optical system guides projection light from the projection optical system to a pupil of the viewer. The holographic element deflects first-order diffracted light toward the pupil of the viewer, and has a positive focal length for the first-order diffracted light. At a time of viewing of the image, the projection light enters the eyepiece optical system at an angle that is equal to or larger than θ expressed by the following expression,θ=arctan((3.5+M)/f)where a focal length of the eyepiece optical system for the projection light is “f” [mm], and a maximum effective radius in an upper-lower direction with respect to the pupil of the viewer for the first-order diffracted light of the holographic element is “M” [mm].
