Recirculation of reflected source light in an image projection system

A method of increasing the brightness of an image projected by, and the optical efficiency of, an image projection system implemented with a lamp assembly including a primary light source and a light reflector having an inner surface, comprising:

• producing a light beam having light beam portions characterized by optical properties and transmitting the light beam through the lamp assembly;
• directing the light beam for incidence on a spatially nonuniform light filter, the light filter having first and second spatial regions that transmit light characterized by respective first and second different sets of optical properties, the first spatial region reflecting in directions generally opposite to the beam propagation direction of the light beam portions characterized by the second set of optical properties, and the second spatial region reflecting in directions generally opposite to the beam propagation direction of the light beam portions characterized by the first set of optical properties;
• and
• redirecting at least some of the light beam portions reflected by the first and second spatial regions into the lamp assembly so that at least some of the light beam components reflected by the first and second spatial regions of the light filter reflect off of the inner surface of the light reflector and propagate through the respective second and first spatial regions of the light filter to increase by light recirculation the optical efficiency of, and the brightness of the image produced by, the image projection system.