OPTICAL SYSTEM

An optical system includes a phase retardation plate which controls a polarization of an input laser beam, an axicon lens spaced apart from the phase retardation plate on an emitting surface side thereof to convert the input laser beam into a single first Bessel beam having a single cone angle, a collimating lens spaced apart from the axicon lens on an emitting surface side thereof to collimate the single first Bessel beam in a form of a single second Bessel beam having an annular energy distribution, a polarizing beam splitter spaced apart from the collimating lens on an emitting surface side thereof to split the single second Bessel beam into third Bessel beams having different polarization directions, and a focusing lens spaced apart from the polarizing beam splitter on an emitting surface side thereof to focus the plurality of third Bessel beams to form an output laser beam.