Wavelength conversion member including phosphor that converts light from semiconductor light-emitting element into longer-wavelength light

A light source, comprising:

• a semiconductor light-emitting element that emits excitation light having a peak wavelength of 420 nm or more and 470 nm or less;
• and
• a wavelength conversion member including:
• a substrate;
• a first wavelength conversion layer on the substrate, the first wavelength conversion layer containing a first phosphor and a first matrix;
• and
• a second wavelength conversion layer having:
• a first main surface facing the first wavelength conversion layer;
• and a second main surface on which excitation light from a semiconductor light-emitting element is incident, the second wavelength conversion layer containing a second phosphor, first inorganic particles, and a second matrix, wherein
• the first phosphor and the second phosphor convert at least part of the excitation light incident on the second main surface into first light having longer wavelengths than the excitation light,
• the first light is emitted from the second main surface of the second wavelength conversion layer, and
• a volume Vp1 of the first phosphor, a volume Vw1 of the first wavelength conversion layer, a volume Vp2 of the second phosphor, and a volume Vw2 of the second wavelength conversion layer satisfy Vp1/Vw1>Vp2/Vw2.

A vehicle headlamp, comprising:

• a light source including a wavelength conversion member and a semiconductor light-emitting element that emits excitation light having a peak wavelength of 420 nm or more and 470 nm or less;
• and
• an exit optical system that guides light from the light source to the outside,
• the wavelength conversion member including:
• a substrate;
• a first wavelength conversion layer on the substrate, the first wavelength conversion layer containing a first phosphor, and a first matrix;
• and
• a second wavelength conversion layer having:
• a first main surface facing the first wavelength conversion layer;
• and a second main surface on which excitation light from a semiconductor light-emitting element is incident, the second wavelength conversion layer containing a second phosphor, first inorganic particles, and a second matrix, wherein
• the first phosphor and the second phosphor converting at least part of the excitation light incident on the second main surface into first light having longer wavelengths than the excitation light,
• the first light is emitted from the second main surface of the second wavelength conversion layer, and
• a volume Vp1 of the first phosphor, a volume Vw1 of the first wavelength conversion layer, a volume Vp2 of the second phosphor, and a volume Vw2 of the second wavelength conversion layer satisfy Vp1/Vw1>Vp2/Vw2.