Patent attributes
An illumination optical system 1 includes a light source 11 including a plurality of light emitting sections 11a, 11b, and 11c arrayed in a specific direction, and an integrator 21 including a plurality of lens cells arrayed in the specific direction, and it illuminates a plane to be illuminated 31 by a light beam emitted from the plurality of light emitting sections and passing through the integrator. A plurality of light beams from the plurality of light emitting sections enter an incident surface of the integrator with a shift from each other in the specific direction, as divergent light beams, each of which spreads in the specific direction. Two light beams from two light emitting sections adjacent to each other among the plurality of light emitting sections are overlapped with each other in a region Lm larger than one of the lens cells on the incident surface of the integrator.
