Patent ID: 8562152

Claim:
A collimator lens unit that comprises at least two lenses and substantially collimates a beam of light emitted from a solid-state light source unit of a Lambert emission type, wherein at least two faces of incidence faces and emission faces of the lenses constituting the at least two lenses are aspheric faces, at least one front aspheric face located close to the solid-state light source unit out of the at least two aspheric faces has a luminous flux density distribution changing function of changing a luminous flux density distribution of the beam of light emitted from the solid-state light source unit to a predetermined luminous flux density distribution in which the luminous flux density in the vicinity of an optical axis of the collimator lens unit is higher than the luminous flux density in a peripheral portion separated from the optical axis of the collimator lens unit, the rear aspheric face farthest from the solid-state light source unit out of the at least two aspheric faces has a function of substantially collimating the beam of light formed with the predetermined luminous flux density distribution, and the luminous flux density in the vicinity of the optical axis of the collimator lens unit in the beam of light emitted from the collimator lens unit is higher than the luminous flux density in a peripheral portion separated from the optical axis of the collimator lens unit.