Light source apparatus, illuminator, and projector

A light source apparatus comprising:

• a light source unit that outputs a light beam flux formed of a plurality of light beams;
• and
• a reduction system that includes P optical elements including a first optical element and a second optical element and reduces a cross section of the light beam flux, the cross section being defined by first direction and a third direction perpendicular to the first direction, wherein
• the P optical elements each have
• a first surface having optical transparency,
• a second surface that faces the first surface and has optical transparency,
• a first reflection surface that is provided at a first end and inclines with respect to a normal to the first surface, and
• a second reflection surface that is provided at a second end that faces the first end and inclines with respect to a normal to the second surface,
• the P optical elements each allow a corresponding light beam of the light beam flux to pass through the first surface, to be incident on the first reflection surface, to be sequentially reflected off the first reflection surface and the second reflection surface, and to further exit through the second surface to shift an optical path of the light beam in the first direction,
• the light beam flux enters the reduction system along a second direction that intersects the first direction and the third direction,
• the light beam flux continues to travel in the second direction after passing through the reduction system with the reduced cross section,
• the first optical element and the second optical element are sequentially provided in the second direction, and
• (1) the first reflection surface of the second optical element is shifted from the first reflection surface of the first optical element in a direction opposite the first direction, or
• (2) the second reflection surface of the second optical element is shifted from the second reflection surface of the first optical element in the direction opposite the first direction.