Method and apparatus for laser drilling

A drilling apparatus comprising:

• a laser which produces a pulsed laser beam, a pulse of the pulsed laser beam having an energy of less than or equal to 0.1 joule and a pulse width of less than or equal to 500 nanoseconds and a peak power of at least 10,000 watts, the pulsed laser beam having a first frequency component;
• and
• a harmonic generator which generates a second frequency component, the second frequency being greater than the first frequency;
• wherein the laser beam, after passing through the harmonic generator, is incident on an article comprising a substrate coated with a nonmetallic layer to vaporize the nonmetallic layer.

A method of drilling a hole in an article, the article comprising a substrate coated with a nonmetallic layer, the method comprising the steps of:

• generating a pulsed laser beam, a pulse of the pulsed laser beam having a peak power of greater than 100,000 watts and less than or equal to 10,000,000 watts;
• directing the pulsed laser beam at the article to vaporize the nonmetallic layer;
• and
• directing the pulsed laser beam at the article to vaporize the substrate.

A method of drilling a hole in an article, the article comprising a substrate coated with a nonmetallic layer, the method comprising the steps of:

• generating a pulsed laser beam, a pulse of the pulsed laser beam having a wavelength which is less than or equal to 0.532 microns;
• directing the pulsed laser beam at the article to vaporize the nonmetallic layer;
• increasing the wavelength of the pulsed laser beam;
• and
• directing the pulsed laser beam at the article to vaporize the substrate.