| 摘要 |
A light source device has: a fluorescent material section (1i) that is provided with a fluorescent material; an excitation light source (6) that outputs excitation light that excites the fluorescent material; a reduction optical system (7) that reduces the luminous flux diameter of the excitation light; and a light collecting optical system (8) that collects the excitation light on the fluorescent material section (1i), said excitation light having the luminous flux diameter thereof reduced by means of the reduction optical system (7). The reduction optical system (7) has: a plurality of lenses including two lenses (1c, 1d) having positive power; and a lens moving section (7a) that reciprocates the lens (1c) in the optical axis direction. The lens (1c) is disposed on the excitation light source (6) side, and has a power smaller than that of the lens (1d). A refractive index of the lens (1c) is equal to or smaller than the refractive indexes of other lenses of the reduction optical system (7). |
