In optical projection systems such as projection microscopes and projection televisions, the irradiance on a screen decreases with an increase in the magnification of the projection. To obtain bright images at large magnification, objects must be illuminated or radiate strongly. In conventional optical systems, brightness is conserved during the propagation of rays. The use of an active device which amplifies the brightness is effective for making large screen projection systems.
© 1984 Optical Society of AmericaPDF Article