Abstract: A multiple element lens system for projecting images generated from curved surfaces. A spherical projection lens is provided along a projection axis. An aspheric plate follows the spherical lens, which is followed by a second spherical projection lens. Parfocalizing separate curved image surfaces of different primary colors permits a narrow spectral bandwidth lens system, having an improved speed and resolution, providing combined full color projected images.

Abstract: An aplanatic image combiner. At least two image generating cathode ray tubes are provided having curved concave phosphor image generating surfaces. A set of dichroic mirrors are provided to combine images from each of the curved surfaces into a single combined image. A lens is positioned to transmit the combined image to an image magnification system. The lens has a curved surface forming an exit aperture for the image combiner. The radius of curvature of the lens is configured to be substantially the same as the radius of curvature of each of the concave image generating surfaces of the cathode ray tube. An image is generated to an image magnification system without generating any field aberration or astigmatic and chromatic aberration requiring correction in the magnification system.

Abstract: A multiple tube projection television system. At least two image generating cathode ray tubes are provided, having an image generating surface which is concave. The radius of curvature of the image generating tubes is selected to be between 1.2 and 2 times the image diagonal of each tube. Dichroic mirror means are provided to combine the images produced from each tube. A projection lens system is positioned at an optical distance from each tube which is substantially equal to the radius of curvature of the concave phosphor surface. The combination provides for an optimum amount of light to the entrance aperture of the projection lens system.