Patent ID: 6857745

Claim:
A method of manufacturing an illumination optical unit, including a light source a beam splitting element to split a beam emitted from the light source into a plurality of partial beams; a light focusing element to focus the partial beams; and a polarization converting element to make the polarization directions of the partial beams uniform, the method comprising: first adjusting a relative position on a predetermined optical path of the light focusing element and the polarization converting element on the basis of the shapes thereof, and fixing the position of the light focusing element and the polarization converting element; introducing a beam on the light focusing element and the polarization converting element of which position is adjusted during the first adjusting and the beam splitting element disposed on the predetermined optical path; transmitting the beam introduced by the beam introducing into the light focusing element, the polarization converting element and the beam splitting element to form an optical image on a projection screen; detecting the optical image formed in the optical image forming; calculating a comparison result of an illumination area of the optical image detected in the optical image detecting with a designed illumination area; determining whether the illumination area of the optical image is in the optimal state with respect to the designed illumination area or not on the basis of the comparison result from the illumination-area comparing; adjusting the relative position of the beam splitting element with respect to the light focusing element and the polarization converting element on the basis of the comparison result calculated in the illumination area comparing, when the illumination area of the optical image is determined not in the optimal position in the optimal-state determining; and fixing the position of the beam splitting element when the illumination area of the optical image is determined to be in the determined optimal state in the optimal-state determining.