Abstract: A light source apparatus for separating a white light into light components of a plurality of colors, includes a white light source and at least two dichroic mirrors. Each mirror selects a light with a particular wavelength band from a visible light so as to transmit the light with the selected wavelength band therethrough. The mirrors reflect light with a wavelength band other than the selected wavelength band so that the transmitted wavelength bands of the mirrors are different from each other. The mirrors are arranged opposite to each other with respect to the white light source. The apparatus also includes condenser lenses which are combined with each of the dichroic mirrors. The light reflected by each of the dichroic mirrors is returned to the white light source.

Abstract: An optical projection system has been provided which is particularly suited for use in microlithography and includes a source of exposure energy for generating a beam of energy. A primary lens and mirror are located in the path of the beam for receiving the beam and passing only a portion of the beam therethrough. A refractive lens group is located in the path of the portion of the beam for receiving and transmitting that portion. A recticle element is located in the path of the portion of the beam and has a uniform thickness having a pattern on one surface thereof and an unpatterned portion adjacent thereto. The reticle element is positioned for permitting the portion of the beam to pass through its thickness and for reflecting the portion of the beam back through its thickness and the refractive lens group to the primary lens and mirror.