| 摘要 |
PURPOSE:To form a light source device generating light flux having almost uniform light distribution by using a phenomenon that a refractive index in a thermal refractive index medium is changed by heat. CONSTITUTION:The external surface, i.e. a point A, of a thermal refractive index medium 4 corresponding to the center of a thickly wound filament part is heated up to the highest temperature and a gradient index area increasing the refractive index gradually from the point A having the lowest refractive index to the periphery is formed. Since the quantity of light flux from a thin filament part is comparatively small, the thermal refractive index medium 4 heated by the light flux is not heated up to the formation of thermal gradient and the gradient index area is not formed. Therefore, an object to be illuminated is uniformly illuminated by receiving direct light from thick and thin parts of the filament 2 of a lamp 1 respectively, light flux reflected by a reflector 3 through the thermal refractive index medium 4 and projected as divergent light and the light flux reflected through the thermal refractive index medium 4 without being diversed by the reflector 3. |
