Laser light irradiation apparatus and laser light irradiation method

A laser light irradiation apparatus comprising:

• a laser oscillator;
• a beam expander optical system having a zoom function, wherein the beam expander optical system includes a first lens, a second lens, and a third lens in order in a traveling direction of laser light oscillated from the laser oscillator;
• a correction lens disposed between the laser oscillator and the beam expander optical system;
• and
• a mechanism to change a distance between the first lens and the second lens in order to expand or reduce a beam diameter of the laser light,
• wherein the first lens is a concave lens, and
• wherein the third lens is cooperated with the second lens to make the laser light parallel.

A laser light irradiation apparatus comprising:

• a laser oscillator;
• a beam expander optical system having a zoom function, wherein the beam expander optical system includes a first lens, a second lens, and a third lens in order in a traveling direction of laser light oscillated from the laser oscillator;
• a correction lens disposed between the laser oscillator and the beam expander optical system;
• and
• a mechanism to change a distance between the first lens and the second lens in order to expand or reduce a beam diameter of the laser light,
• wherein the first lens is a convex lens, and
• wherein the third lens is cooperated with the second lens to make the laser light parallel.

A laser light irradiation method comprising the steps of:

• emitting laser light from a laser oscillator;
• making the laser light enter a correction lens;
• and
• making the laser light emitted from the correction lens enter a first lens, a second lens, and a third lens of a beam expander optical system having a zoom function in order,
• wherein the first lens is a concave lens,
• wherein the second lens is moved to change a distance between the first lens and the second lens, thereby expanding or reducing a beam diameter of the laser light,
• wherein the third lens is cooperated with the second lens to make the laser light parallel, and
• wherein a laser oscillator, a correction lens, and a first lens are disposed so that, when an emission point of the laser oscillator is a first conjugate point, a point at which an image at the first conjugate point is formed through the correction lens is a second conjugate point, a distance between the correction lens and the second conjugate point is B, a focal length of the first lens is f, and a distance between the correction lens and the first lens is X, X satisfies B−3|f|≦X≦B+|f|.

A laser light irradiation method comprising the steps of:

• emitting laser light from a laser oscillator;
• making the laser light enter a correction lens;
• and
• making the laser light emitted from the correction lens enter a first lens, a second lens, and a third lens of a beam expander optical system having a zoom function in order,
• wherein the first lens is a convex lens,
• wherein the second lens is moved to change a distance between the first lens and the second lens, thereby expanding or reducing a beam diameter of the laser light,
• wherein the third lens is cooperated with the second lens to make the laser light parallel, and
• wherein a laser oscillator, a correction lens, and a first lens are disposed so that, when an emission point of the laser oscillator is a first conjugate point, a point at which an image at the first conjugate point is formed through the correction lens is a second conjugate point, a distance between the correction lens and the second conjugate point is B, a focal length of the first lens is f, and a distance between the correction lens and the first lens is X, X satisfies B−f≦X≦B+3f.