Patent ID: 8801204

Claim:
An illumination apparatus comprising: an excitation light source configured to emit an excitation light, wherein a direction in which the excitation light is emitted at the highest intensity defines an optical axis; and a wavelength converter arranged downstream from the excitation light source in the direction in which the excitation light is emitted, the wavelength converter comprising: a first fluorescent member configured to absorb at least a portion of the excitation light and to emit a first fluorescent light different from the excitation light; and a second fluorescent member configured to absorb at least a portion of the excitation light and to emit a second fluorescent light different from the excitation light, wherein: the wavelength converter has a cross-section that is substantially circular and substantially perpendicular to the optical axis, a center axis of the wavelength converter that passes through the center of the cross-section substantially coincides with the optical axis, and in a concentric annular region of the cross-section, the concentric annular region being defined between a first circle that is substantially centered on the optical axis and has a first radius, and a second circle that is substantially concentric to the first circle and has a second radius of a predetermined value, a ratio between: a first area occupied by the first fluorescent member in the concentric annular region, and a second area occupied by the second fluorescent member in the concentric annular region, is substantially constant irrespective of a value of the first radius.