▎ 摘　　要

NOVELTY - Wavelength conversion element (200a) comprises a substrate, a wavelength conversion layer, a reflective layer, and a heat conductive layer, where the wavelength conversion layer is disposed on the substrate, the reflective layer is disposed on the substrate and is located between the substrate and the wavelength conversion layer, and the heat conductive layer is disposed on the substrate. At least a portion of the heat conductive layer is located between the substrate and the reflective layer. The heat conductive layer comprises a heat conductive material including graphene, diamond, silver, copper, aluminum, gold and/or silicon carbide and a filler material including silicon dioxide colloid, zirconium dioxide colloid, silicone resin, epoxy resin, ceramic resin, silicone, silica sol, silicate, phosphate, sulfate and/or borate. A material of the base board comprises aluminum, and a material of the surface treatment layer comprises alumina. USE - The wavelength conversion element is useful in projector (claimed). ADVANTAGE - The wavelength conversion element: enhances optical conversion efficiency; and utilizes the surface treatment layer that exhibits reflective property, excitation light or by laser light leaked by the reflective layer may be reflected, so that light utilization efficiency is improved. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a projector (10). DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a projection apparatus. Projector (10) Light-emitting unit (100) Wavelength conversion element (200a) Light valve (300) Projection lens (400)