| 摘要 |
PURPOSE:To make the state of the wavelength selective means such as the filter into a thermally stationary state and to prevent the characteristics of transmittivity of the filter from changing by a method wherein the selective means is disposed on the side of the light source of the shutter. CONSTITUTION:The wavelength selective means such as a filter 5 is disposed before a shutter 6. The filter 5 is irradiated with the cool light from a cold mirror 3. Accordingly, when the characteristics of luminous intensity of a light source 1 is regarded as an almost constant, the amount of incident light of the cool light into the filter 5 is always constant, and subsequently to the warming-up of the illumination optical device, the state of the filter 5 becomes a stationary state on its amount of absorption light. By this way, the characteristics of transmittivity of the filter 5 can be prevented from changing. |
