Light wavelength conversion member and light emitting device
An optical wavelength conversion member ( 9 ) provided with a ceramic plate ( 11 ) which is configured from a polycrystalline body that is mainly composed of Al 2 O 3 and a component represented by A 3 B 5 O 12 :Ce; and each of A and B in A 3 B 5 O 12 represents at least one element selected from the element groups described below. In addition, a dielectric multilayer film ( 13 ) which transmits a specific wavelength and reflects another specific wavelength is formed on a light incident surface ( 11 a ) of the ceramic plate ( 11 ). The ceramic plate ( 11 ) has a porosity of 2% by volume or less, while having an average surface roughness (an arithmetic mean roughness Sa) of 0.5 μm or less. A: Sc, Y and lanthanoids (excluding Ce) B: Al and Ga. Also disclosed is a light-emitting device including the optical wavelength conversion member.
1. An optical wavelength conversion member comprising a polycrystalline ceramic plate containing, as main components, Al 2 O 3 and a component represented by A 3 B 5 O 12 :Ce, the optical wavelength conversion member being characterized in that:
each of A and B of the A 3 B 5 O 12 is at least one element selected from the following element groups:
A: Sc, Y, and lanthanoids (except for Ce), and
B: Al and Ga; and
the ceramic plate has a porosity of 0.05 vol. % or less and an average surface roughness (arithmetic average roughness Sa) of 0.5 μm or less, and the ceramic plate has, on its surface located on one side in a thickness direction thereof, a dielectric multilayer film including stacked translucent layers having different refractive indices.
2. An optical wavelength conversion member according to claim 1 , wherein the ceramic plate has open pores at the interface between the dielectric multilayer film and the ceramic plate in a cross section of the optical wavelength conversion member in the thickness direction; the number of open pores is 30 or less per 100 μm of the length of the interface; and each open pore has an opening size of 2 μm or less.
3. An optical wavelength conversion member according to claim 1 , wherein the ceramic plate has an A 3 B 5 O 12 :Ce content of 5 to 50 vol. %.
4. An optical wavelength conversion member according to claim 1 , wherein the Ce content of the A 3 B 5 O 12 :Ce is 10.0 mol % or less (exclusive of 0) relative to the element A.
5. An optical wavelength conversion member according to claim 1 , wherein the ceramic plate has, on its surface located on the other side in the thickness direction thereof, a translucent antireflection layer for preventing light reflection.
6. A light-emitting device comprising an optical wavelength conversion member as recited in claim 1 , the light-emitting device being characterized in that:
light is incident on the surface of the optical wavelength conversion member on which the dielectric multilayer film is provided.
7. An optical wavelength conversion member according to claim 1 , wherein the dielectric multilayer film comprises a plurality of high refractive index films and a plurality of low refractive index films alternately disposed one by one, wherein the high refractive index films have a refractive index that is higher those of the low refractive index films.
8. An optical wavelength conversion member according to claim 1 , wherein the dielectric multilayer film transmits or reflects light of a specific wavelength.
9. An optical wavelength conversion member according to claim 1 , wherein the dielectric multilayer film comprises a dichroic coating.
10. An optical wavelength conversion member according to claim 7 , wherein the dielectric multilayer film comprises alternately stacked high refractive index titanium oxide films and low refractive index silicon oxide films.