Method for machining micro-holes in metal or alloy product

A method for machining micro-holes in a metal or alloy product, comprising steps of:

• step A. an ultra-short laser pulse generator generating ultra-short laser pulses and outputting the ultra-short laser pulses to a laser state adjusting device;
• step B. the laser state adjusting device regulating a diameter of a spot formed by the ultra-short laser pulses output by the ultra-short laser pulse generator to a required first spot diameter, splitting the regulated ultra-short laser pulses into a first laser beam and a second laser beam, and outputting the first laser beam and the second laser beam to a Gaussian laser pulse generating device and a ring laser pulse generating device respectively, wherein laser pulses of each of the first laser beam and the second laser beam per unit time are in number of a preset value;
• step C. the Gaussian laser pulse generating device regulating power of the first laser beam, collimating the first laser beam, regulating a spot of the first laser beam to have a required second spot diameter, delaying the regulated first laser beam to generate Gaussian laser pulses, and outputting the Gaussian laser pulses to the laser pulse combining device, wherein an optical path difference between an optical arm formed by the Gaussian laser pulse generating device and an optical arm formed by the ring laser pulse generating device is within a preset range;
• step D. the ring laser pulse generating device regulating power of the second laser beam, collimating the second laser beam, regulating a spot of the second laser beam to have a required third spot diameter, then modulating the regulated second laser beam into ring laser pulses, pre-focusing the ring laser pulses and outputting the pre-focused ring laser pulses to the laser pulse combining device;
• and
• step E. the laser pulse combining device combining the Gaussian laser pulses and the ring laser pulses to generate mixed ultra-short laser pulses, focusing the mixed ultra-short laser pulses, and directing the focused mixed ultra-short laser pulses to hit the metal or alloy product to be inspected,
• wherein, a ratio between a diameter of a central ring of a ring spot formed by the pre-focused ring laser pulses and a diameter of a central ring of a Gaussian spot formed by the focused Gaussian laser pulses is greater than 1.