Wavelength conversion element, projection device and manufacturing method of wavelength conversion element

A projection device, comprising:

• an illumination system, adapted to provide an illumination beam;
• a light valve, disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam;
• and
• a projection lens, disposed on a transmission path of the image beam,
• wherein the illumination system comprises an excitation light source and a wavelength conversion element, the excitation light source is adapted to provide an excitation beam, the wavelength conversion element is disposed on a transmission path of the excitation beam, and the wavelength conversion element is adapted to convert the excitation beam into a converted beam, and the illumination beam includes the converted beam, the wavelength conversion element comprising:
• a substrate;
• a wavelength conversion layer, disposed on the substrate, wherein the wavelength conversion layer includes an inorganic adhesive and a wavelength conversion material, and the wavelength conversion material is mixed with the inorganic adhesive;
• and
• a first inorganic interstitial layer, disposed between the wavelength conversion layer and the substrate.

A manufacturing method of a wavelength conversion element, comprising:

• providing a wavelength conversion layer, the wavelength conversion layer has a first surface and a second surface relative to the first surface;
• disposing a first inorganic interstitial layer on the first surface of the wavelength conversion layer, the first inorganic interstitial layer has a third surface and a fourth surface relative to the third surface, and the fourth surface faces the first surface;
• and
• bonding the third surface of the first inorganic interstitial layer to a substrate to dispose the first inorganic interstitial layer between the wavelength conversion layer and the substrate.