Illumination apparatus

摘要

An illumination apparatus is disclosed which efficiently irradiates an irradiation surface (2) without destroying the symmetry of an illuminance distribution at the irradiation surface (2). A light source (4) is displaced from a center of curvature (6a) of a spherical mirror (6) in a direction in a displacement plane which includes an axis of symmetry (SA) of the spherical mirror (6) so as to form a light source image at a position off the light source (4). Due to this, a ray from the spherical mirror (6) passes off the light source (4) (i.e., the position of the light source image), and therefore, a reflection ray is not shielded, absorbed nor otherwise disturbed by the light source (4), which in turn prevents deterioration in the efficiency of utilization of light. Further, the light source (4), the spherical mirror (6) and the lens (8) are assembled into a light source unit (12) which is inclined at an angle about a principal point of the lens (8) with respect to a central axis (CA) of the irradiation surface (2) and displaced a certain distance in a displacement direction (X) which is perpendicular to the central axis (CA). Hence, the illuminance distribution at the irradiation surface is adjusted and the symmetry of the illuminance distribution at the irradiation surface is improved.