Illumination optical device suitable for projection display apparatus

摘要

Platelike first transparent members (321) and platelike second transparent members (322) are prepared. Each first transparent member has substantially parallel first and second surfaces (film forming surfaces). A polarization splitting film (331) is formed on the first film forming surface. A reflecting film (332) is formed on the second film forming surface. The films are not formed on the surfaces of the second transparent members (322). A plurality of the first transparent members (321) and a plurality of the second transparent members (322) are adhered alternately. A block is cut from the so-adhered transparent members at a prescribed angle to the surfaces and the cut surfaces thereof are polished to obtain a polarization beam splitter array (320). A plurality of small lenses is arranged on the incident plane of the beam splitter array.