Multi-pulse laser beam generation method and device and laser beam machining method and apparatus using multi-pulse laser beam

A multi-pulse laser beam apparatus, comprising:

• a laser beam oscillation source means for oscillating a pulse laser beam of a single wavelength;
• a polarization beam splitter means for splitting a pulse laser beam into plural laser beams and having two optical axes of an incidence and an oscillation of a laser beam on each one side of a plate, totalling four optical axes of first, second, third and fourth optical axes on both sides;
• non-linear polarization means connected to said third and fourth optical axes of said polarization beam splitter means to change on directional laser beam from said polarization beam splitter means into a non-linearly polarized beam;
• time delay means formed of a light transmissive material, coupled to said non-linear polarization means for providing a time delay to a laser beam by transmission through a length of an optical path constituted by said light transmissive material;
• and beam direction alteration means for guiding a pulse laser beam having passed through said non-linear polarization means and said time delay means again to said fourth optical axis of said beam splitter means to thereby apply a pulse laser beam to said first optical axis of said polarization beam splitter means from said laser beam oscillation source means and to output a laser beam from said second optical axis as an output multi-pulse laser beam.

A multi-pulse laser beam apparatus, comprising:

• a pulse laser beam oscillator means for oscillating a pulse laser beam;
• a polarization beam splitter means for separating a pulse laser beam oscillated from said pulse laser beam oscillator mans into laser beams of two directions;
• non-linear polarization and time delay means for changing one of laser beam separated into two directions by said polarization beam splitter means into a non-linearly polarized laser beam and for providing a time delay to said non-linearly polarized laser beam by transmission through a length of a light transmission material and applying the time delayed laser beam again to said polarization beam splitter means;
• and wavelength conversion means for wavelength converting a part of a multi-pulse laser beam from said polarization beam splitter means into a pulse laser beam of a different wavelength.

A multi-pulse laser beam method comprising the steps of:

• (a) separating one pulse laser beam oscillated from a pulse laser beam oscillator into linearly polarized laser beams in first and second directions by a polarization beam splitter;
• (b) applying only one of said two separated laser beams to a non-linear polarization and time delay member constituted by glass material to provide a time delay to said only one of said two separated laser beams and to disturb the linear polarization state thereof;
• (c) directing the time delayed and non-linear polarized pulse laser beam again to said polarization beam splitter, said polarization beam splitter and said glass material forming a beam circulating loop;
• and (d) repeating said steps (a) to (c) through said beam circulating loop to output a multi-pulse laser beam from said beam splitter.

A multi-pulse laser beam machining system comprising:

• a multi-pulse laser beam generator, comprising:
• a pulse laser beam oscillator means for oscillating a pulse laser beam a polarization beam splitter means for separating a pulse laser beam oscillated from said pulse laser beam oscillator means into laser beams in first and second directions and for applying a laser beam in said first direction to an output end of the generator;
• and non-linear polarization and time delay means for non-linearly polarizing a laser beam in said second direction from said polarization beam splitter means ad for providing a time delay to said non-linearly polarized laser beam by an amount of time by transmission through a length of an optical path constituted by an optically transmissive material so as to direct the delayed laser beam again to said polarization beam splitter means and to provide the delayed pulse laser beam separated in said first direction by said polarization beam splitter means at said output end;
• wavelength conversion means including a wavelength conversion element for changing a wavelength of a part of the pulse laser beam of a multi-pulse laser beam from said output and of said multi-pulse laser beam generator to produce a short-wavelength beam and to pass a remaining part of the pulse laser beam of the multi-pulse laser beams as an original-wavelength beam;
• and
• laser beam applying means for applying said short and original-wavelength laser beams from said wavelength applying conversion means to a workpiece to thereby perform a laser beam machining operation.