| 摘要 |
PURPOSE:To display a video on a screen by projecting a light image and to observe a body, etc., behind the screen through the screen by providing a member which switches a transparent state and a light scattering state, and a hologram element which is combined with the member to diffract incident light at a specific angle. CONSTITUTION:The member 136 where the transparent state and light scattering state are switched and set and the hologram element 133 are set in combination and the hologram element 133 diffracts and projects the incident light. Then the member 136 is set in the light scattering state and even when the light from a recording medium 15 is projected on this member 136, the light at the time of the projection is diffracted by the hologram element 133 at the specific angle. For the purpose, the diffraction angle is set to an observer's direction and the scattered light passed through the member 136 reaches the observer sufficiently. Consequently, the body present behind the screen 13 can be observed through the screen 13, which is placed in the light scattering state when necessary to display a video by a hologram, etc., selectively. |
