A light source comprising an excitation light source for providing excitation light, and an optical wavelength conversion member disposed at a distance from the excitation light source. The optical wavelength conversion member comprises an optical wavelength conversion material for converting the excitation light into stimulated light. The light source also comprises an optical-guiding member that allows the excitation light to be incident on the optical wavelength conversion material, and an optical-collecting member for collecting converted light originating from the optical wavelength conversion material. To separate the paths of the converted light and the excitation light, the etendue of the optical-guiding member is less than or equal to ¼ of the etendue of the optical-collecting member. This allows the optical-guiding member to draw in the excitation light while preventing the excessive escape of the converted light through the optical-guiding member.