Light illuminating apparatus

A light illuminating apparatus for irradiating, to a preset irradiation position on a reference irradiation surface, light of a line shape extending in a first direction and having a preset line width in a second direction perpendicular to the first direction, the light illuminating apparatus comprising:

• a plurality of light emitting units, each comprising a substrate, a plurality of light sources arranged at a preset interval along the first direction on the substrate and placed such that a direction of an optical axis is matched to a direction perpendicular to the substrate surface, and a plurality of optical devices placed on optical paths of each of the light sources to shape light from each of the light sources into light with a preset divergence angle,
• wherein the plurality of light emitting units is arranged on an arc having its center at the irradiation position, when viewed in the first direction, and
• an irradiation width in the second direction of light emitted from the plurality of light emitting units is approximately equal within a preset range in a direction perpendicular to the irradiation surface.