Slide projector with variable focal length objective lens - also mechanism for decentring the slide

摘要

A slide projector is fitted with a magazine, containing the slides, fitted so as to permit the displacement of the slide perpendicular to the optical axis of the projector along two orthogonal axes. This movement enables any chosen part of the slide (0) to be centred in the optical axis. The projector has means of illumination for lighting the slide (0) in the magazine and has an optical system (L1, L2) for transmitting the slide picture onto a screen, having a variable focal length objective which creates, from the region of the slide on the centre of the optical axis, a reel aerial image (I) on an intermediate fixed plane. A field diaphragm of determined dimensions is placed on this fixed intermediate plane, and is centred on the optical axis so that the image plane is the same size as the field diaphragm and a projection objective and to form with this system (M, C, D,) on the optical axis is in a position a fixed determined distance from the plane of the slide to be projected.