IMAGE PROJECTING APPARATUS

摘要

The present invention provides an image projecting apparatus (10), particularly a rear screen projecting apparatus, comprising a projecting lensing means (20) for projecting an image of an illuminated object, a screen (18), and reflecting means (30) for reflecting light from the projecting lensing means onto the screen; wherein the reflecting means is positioned off-centre with respect to the screen and asymmetric diverging lensing means (30) are provided for magnifying further the image reflected by the reflecting means onto the screen, the lensing power of the diverging lensing means varying across the area thereof, such that for each point on the diverging means, the combined focal length of the projecting lensing means and diverging lensing means is adjusted according to the length of the optical path between the projecting lensing means and the screen via that point, thereby to reduce optical distortion of the image on the screen. In some embodiments, said diverging lensing means may comprise a toroidal aspheric mirror or a complex aspheric mirror.