摘要：

An improved projection printer prints a circuitry pattern from a reticle onto a wafer by using a mercury arc source, a beam splitter, and a focusing mirror. The beam splitter is a polarizing beam splitter, and a polarization altering means is arranged between the polarizing beam splitter and the focusing mirror, allowing the radiant energy reflected from the focusing mirror to pass straight through the polarizing beam splitter to the wafer being printed. A system for optically registering the wafer and the reticle includes a source of visible radiant energy of a longer wavelength range and a microscope arranged for observing the reticle. The visible radiant energy is polarized and directed to the polarizing beam splitter in an orientation to pass straight through the beam splitter and be incident on the wafer. The visible radiant energy reflected from the wafer to the focusing mirror and back to the polarizing beam splitter has its polarization altered to be split be the polarizing beam splitter for imaging the wafer on the reticle for viewing through the microscope.

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