Patent ID: 8023178

Claim:
A line laser beam flux irradiating apparatus comprising: a laser beam flux source which emits a divergent laser beam flux; a conversion lens which converts the divergent laser beam flux to a parallel laser beam flux; a first lens which forms a first line laser beam flux; a second lens which forms a second line laser beam flux intersecting the first line laser beam flux; a reflective optical system comprised of a first reflective surface which reflects the parallel laser beam flux toward the first lens and a second reflective surface which reflects the parallel laser beam flux toward the second lens; and a laser beam flux switching device which is disposed between the reflective optical system and the conversion lens and guides the parallel laser beam flux to the first reflective surface and the second reflective surface so as to switch a course of the parallel laser beam flux between a first laser beam flux state in which a cross-wise line laser beam flux is formed by the cooperation of the first line laser beam flux and the second line laser beam flux, a second laser beam flux state in which the parallel laser beam flux is guided to the first reflective surface so as to form only the first line laser beam flux, and a third laser beam flux state in which the parallel laser beam flux is guided to the second reflective surface so as to form only the second line laser beam flux, wherein the first reflective surface reflects the parallel laser beam flux which transmits the second reflective surface; wherein the divergent laser beam flux comprises a linearly polarized laser beam flux, and the laser beam flux switching device has a ¼λ retardation plate which converts the linearly polarized laser beam flux of the parallel laser beam flux converted by means of the conversion lens into a circularly polarized laser beam flux, a ½λ retardation plate which linearly converts the linearly polarized laser beam flux in a polarized direction perpendicular to a polarized direction of the linearly polarized laser beam flux, and a transmission window which transmits the linearly polarized laser beam flux while maintaining the polarized direction of the linearly polarized laser beam flux, wherein the second reflective surface has a polarization property which totally reflects the linearly polarized laser beam flux transmitted while maintaining the polarization direction of the linearly polarized laser beam flux toward the second lens, and wherein the first reflective surface has a polarization property which totally reflects the laser beam flux linearly polarized in a polarization direction perpendicular to a polarization direction of the laser beam flux by means of the ½λ retardation plate toward the first lens.