Wavelength-converting element, projection apparatus, and manufacturing method of wavelength-converting element

A projection apparatus, comprising:

• an illumination system, a light valve and a projection lens, wherein
• the illumination system is adapted to provide an illumination beam,
• the light valve is disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam,
• the projection lens is disposed on a transmission path of the image beam,
• the illumination system comprises an exciting light source and a wavelength-converting element, wherein
• the exciting light source is adapted to provide an exciting beam,
• the wavelength-converting element is disposed on a transmission path of the exciting beam, a wavelength-converting layer of the wavelength-converting element is adapted to convert the exciting beam into a converted beam, the illumination beam comprises the converted beam, and the wavelength-converting element comprises a substrate, the wavelength-converting layer and a diffuse reflection layer, wherein
• the wavelength-converting layer is disposed above the substrate;
• and
• the diffuse reflection layer is disposed between the substrate and the wavelength-converting layer, the diffuse reflection layer comprises an inorganic binder and a plurality of diffuse reflection particles, the plurality of diffuse reflection particles are mixed with the inorganic binder, and the inorganic binder comprises an alcohol-soluble inorganic binder or a water-soluble inorganic binder.