Polarization conversion element, polarization-conversion-element manufacturing method, light-source unit, and optical device

A polarization conversion element comprising:

• a polarizing beam-splitter array formed to bond a first light-transmitting member with a polarization separation layer that transmits either one of a P wave or a S wave and reflects the other one, and a second light-transmitting member with a reflective layer that reflects the other one of the P wave or the S wave reflected by the polarization split layer, wherein the other one of the P wave or the S wave incident from an incident surface being reflected by the reflective layer to an output surface;
• an inorganic half-wave plate which is selectively provided above the output surface of the polarizing beam-splitter array and the inorganic half-wave plate including an obliquely deposited layer made of a dielectric material;
• and
• a protective film that covers side surfaces of the obliquely deposited layer of the inorganic half-wave plate.