Patent ID: 9019597
Filing Date: 2015-04-28
Classification: G02B,G03B

Abstract:
1. A short distance projection device comprising, in light beam propagation direction: an imager providing an image; an ocular formed by a set of lenses forming an approximately parallel light beam from the image provided by the imager; an objective formed by a set of lenses forming an intermediate image with a field curvature from the approximately parallel light beam; and; an aspherical concave mirror generating a final image, the field curvature given by the objective compensating for a deformation introduced by the aspherical concave mirror from the intermediate image; and wherein the short-distance projection device comprises and wherein the lenses forming the objective are adapted to be translated on optical axis in order to enable varying a distance at which the final image is generated such as to provide the short-distance projection device with focus capabilities, and wherein the afocal lens system is composed of a first convergent lens followed by a first divergent lens, a second convergent lens and a second divergent lens.