Method of measuring degradation condition of output mirror in laser oscillator and laser machining apparatus

A laser machining apparatus, comprising:

• a laser oscillator for emitting a laser beam;
• an optical component, placed in a light path of the laser beam that is emitted from the laser oscillator, for transmitting the laser beam;
• an aperture, placed in a light path of the laser beam transmitted through the optical component, for blocking a perimeter portion of the laser beam and for transmitting a middle portion thereof;
• a beam-power measurement means for measuring beam power of a laser beam transmitted through the aperture;
• and
• a control means for determining a degradation condition of the optical component, based on the beam power value measured by the beam-power measurement means when the laser beam is emitted with predetermined beam power.

A method of determining degradation of an output mirror in a laser oscillator, comprising the steps of:

• emitting a laser beam having high beam power with a level at which a thermal lens effect occurs in a degraded output mirror in the laser oscillator;
• measuring a beam power value of the laser beam emitted at the high beam power and transmitted through an aperture, placed in a light path of the laser beam, for blocking a perimeter portion of the laser beam and for transmitting a middle portion thereof;
• and
• determining a degradation condition of the output mirror in the laser oscillator, based on a separately stored criterion value and the measured beam power value.

A method of determining degradation of an output mirror in a laser oscillator, comprising the steps of:

• emitting a laser beam having low beam power with a level at which a thermal lens effect does not occur in a degraded output mirror in the laser oscillator;
• measuring a beam power value of the laser beam emitted at the low beam power and transmitted through an aperture that is placed in a light path of the laser beam so as to block a perimeter portion of the laser beam and to transmit a middle portion thereof;
• emitting a laser beam having high beam power with a level at which a thermal lens effect occurs in the degraded output mirror in the laser oscillator;
• measuring a beam power value of the laser beam emitted at the high beam power and transmitted through the aperture;
• calculating, based on the measured beam power value when the laser beam with the low beam power is emitted, a beam power value when the laser beam with the high beam power is emitted using a non-degraded output mirror in the laser oscillator, using a proportionality equation;
• and
• determining a degradation condition of the output mirror, based on the calculated beam power value and the measured beam power value when the laser beam is emitted with the high beam power.