JPS6461717A - Illuminator - Google Patents

Abstract

PURPOSE:To make the spectral characteristic of a luminous flux which passes an optical filter constant even if the spectral transmission characteristic of the optical filter is altered by disposing two optical filters, at least one of which possesses wavelength selection characteristic, in an opposite direction each other so that they can be movably titled. CONSTITUTION:The luminous flux from a light source 1 becomes almost parallel luminous flux L and is inputted in the optical filter 5 which possesses the wavelength selection characteristic. The intensity of the luminous flux which passes the filter 5 has the distribution of a band in which it becomes the maximum in the specified wavelength and the luminous flux passes the optical filter 6 and is radiated on the surface 10 to be radiated by a condenser lens 9. A light receiving element 13 receives only long wavelength area which is a part of the luminous flux from the way of a projectile optical path through a reflection mirror 11 and a filter 12 for receiving light. The light quantity in the long wavelength area of the light receiving element 13 is altered before and after the filter 5 changes in the lapse of time. Now, the element 13 inputs an output signal in a control part 14 and the control part 14 tilts the optical filters 5 and 6 in the opposite direction by a same angle. The incident angle of the luminous flux L is altered and the illuminance distribution on the surface 10 to be radiated can be uniformized by adjusting the distribution characteristic of the luminous flux which passes the filters 5 and 6 to become an original value.