LASER PROCESSING METHOD, LASER PROCESSING APPARATUS, METHOD OF MANUFACTURING OPTICAL ELEMENT, AND OPTICAL ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide technology for forming a large reformed layer with a large aspect ratio and a processing part into an inside or a surface of a material without causing restriction of a femtosecond laser device, enlarging an optical system, and having restriction of a depth position into the inside of the material.

SOLUTION: A laser processing apparatus 50 includes a laser device 1 and a diffraction type lens 3. The laser processing device 50 emits laser beam 5 (femtosecond laser) having a pulse width equal to or less than 10 picoseconds. The diffractive type lens 3 focuses the laser beam 5 passing through an aperture 2. The laser beam 5 focused by the diffractive type lens 3 is irradiated to a material 8 to be processed. High aberration property in the diffractive type lens is positively utilized by making the design wavelength of the diffractive type lens 3 different from the center wavelength of the femtosecond laser, so that a long focus is made to be deep by spherical aberration.

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