Image display and pick-up apparatus

Claim 1

An image display and pick-up apparatus comprising: a screen which is switchable between a transmissive state and a diffusing state, and has a front side and a rear side, a projection unit, having an optical axis, and arranged at the rear side of the screen for projecting an image onto the rear side of the screen, the image thereby being viewable from the front side of the screen when the screen is in the diffusing state, and a pick-up unit, having an optical axis, and arranged at and facing the rear side of the screen at a predetermined angle for picking up, through the screen, an image of an object located at the front side of the screen, characterized in that the optical axes of the projection unit and pick-up unit are co-planar and intersect at a given acute angle, said predetermined angle being a first acute angle from the rear surface of the screen, and the screen comprises an array of elongated prismatic elements arranged at the front surface of the screen, having their length direction perpendicular to a plane containing the optical axes of the projection unit and the pick-up unit, each element having a facet arranged at an acute elevation angle with respect to the front surface of the screen for deflecting light from the object, incident on the front surface at a second acute angle, towards the pick-up unit.