Patent ID: RE39846

Claim:
An illumination optical apparatus comprising: a light supply means for supplying a beam; a light-source-image forming means for forming a plurality of light source images which are substantially linearly arranged in at least one line, based on the beam from said light supply means; an optical integrator having a plurality of lens elements for forming a plurality of light source images, based on the beam from said light-source-image forming means, said lens elements having a rectangular cross section, two sides adjacent to each other of said rectangular cross section being different in length, said lens elements having a same refracting power both in the direction of the longer side of the rectangular cross section and in the direction of the shorter side thereof; and a first relay optical system disposed between said light-source-image forming means and said optical integrator, for making a position of the light source images formed by said light-source-image forming means conjugate with a position of the light source images formed by said optical integrator said light supply means including: a light source system for emitting light having a beam cross section of substantially square or circle; light source changing means for forming a plurality of light source images, based on the light from said light source system; and a second relay optical system located between said light source changing means and said light-source-image forming means, for making a position of the light source images formed by said light source changing means conjugate with a position of the light source images formed by said light-source-image forming means.