Patent ID: 6461001
Filing Date: 2002-10-08
Classification: G03B

Abstract:
An illumination apparatus comprising:focusing means for focusing light emitted from a light source; columnar optical means having its light entrance portion located in the vicinity of a position where the emitted light is focused by said focusing means, and for propagating the entering light having entered from the light entrance portion and causing the propagated light to exit from its light exit portion; and transferring optical means including a first group of lenses which receive the exiting light from said columnar optical means and which have a positive refracting power, a second group of lenses which receive exiting light from the first group of lenses and which have a positive refracting power, and a third group of lenses which receive exiting light from the second group of lenses and which have a positive refracting power, wherein the respective groups of lenses are successively arrayed from a side of said columnar optical means toward a side of a surface to-be-illuminated and satisfy relationships of inequalities (1) and (2) given below, and wherein the light exit portion of said columnar optical means and the surface to-be-illuminated are held in a conjugate relationship; 0.371/f0<0.62â€ƒâ€ƒ(1) â€ƒ&ugr;p/&ugr;n>1.99â€ƒâ€ƒ(2)wheref0: focal length of said transferring optical means, f1: focal length of said first group of lenses, &ugr;p: means Abbe number of a positive lens included in said second group of lenses, and &ugr;n: means Abbe number of a negative lens included in said second group of lenses.