Off-axis virtual-image display and camera by holographic mirror and blur compensation.

ABSTRACT

We propose off-axis virtual-image display and camera systems, which integrate a vertically-standing holographic off-axis mirror, blur-compensation optical systems, and digital imaging devices. In the system, the holographic mirror is used for an off-axis reflector, which realizes an upright and thin screen for virtual-image formation. By combining it with a display unit, an off-axis virtual-image display is realized, where the virtual image can be seen behind the upright holographic mirror. Simultaneously, by combining it with a camera unit, an off-axis camera is implemented, which realizes frontal shooting of objects by a camera placed at an off-axis position. Since both the off-axis display and the camera can be implemented by a single holographic mirror, it can be applied to a two-way visual-telecommunication system with a thin screen, which implements eye contact and the observer--image distance. A problem with the proposed system is image blur, which is caused by the chromatic dispersion of the holographic mirror. To solve this, we designed optical blur-compensation systems using a diffractive optical element and a diffuser or a lens. Experimental results verify the concept of the proposed systems with clarifying the effect of designed blur-compensation methods.