Patent ID: 7316484

Claim:
An illuminator comprising: a plurality of light source portions, each light source portion including a lamp and a concave mirror; a rod integrator; and a relay lens system that guides a light flux emitted from the rod integrator; wherein the rod integrator is a columnar optical element having an incident end face at a front side and an exit end face at a back side; wherein, when a long-side direction of the exit end face is a horizontal direction and a short-side direction is a vertical direction: of four side surfaces other than the front side and the back side of the columnar optical element, a pair of opposing side surfaces in the horizontal direction is formed as tapered surfaces in which the side surfaces face each other at an inclination of a predetermined angle such that a distance between the side surfaces in the horizontal direction increases from the incident end face toward the exit end face, and a pair of opposing side surfaces in the vertical direction is provided with a portion in which the side surfaces are parallel to each other; wherein light from the light source portions is converged and irradiated onto a vicinity of the incident end face of the rod integrator; wherein two of said light source portions are arranged in the horizontal direction or the vertical direction; and wherein a maximum value in the horizontal direction and a maximum value in the vertical direction of the divergence angle of light emitted from the exit end face of the rod integrator are substantially the same.