ILLUMINATION OPTICAL SYSTEM AND IMAGE PROJECTION DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a small sized image projection device capable of projecting a bright image.SOLUTION: An illumination optical system comprises: a longitudinal section including a normal N and an optical axis Z of a polarization separating surface 17a of PBS 17 ; a first compression system compressing a light beam in each transverse section including an optical axis and being perpendicular to the longitudinal section; a second compression system compressing the light beam in the longitudinal section; a polarization conversion element 15 disposed such that a section including a normal and an optical axis of a polarization separating surface 21 becomes a transverse section; a first fly-eye lens 13 disposed at a prior stage to the polarization conversion element 15; and a second fly-eye lens 14 disposed between the first fly-eye lens 13 and the polarization conversion element 15. Neither the first fly-eye lens 13 nor the second fly-eye lens 14 has optical power in the transverse section.