| 摘要 |
According to the invention, a method and apparatus for generating an Nth harmonic frequency beam (N>2) is provided. A laser fundamental resonator cavity generates a preselected fundamental beam. The laser cavity comprises two fundamental beam reflective mirrors, which define the laser cavity, and a lasing medium. A 2nd or 3rd harmonic cavity is at least partially separate from and the fundamental cavity and at least partially overlaps the fundamental cavity. The harmonic cavity is formed between 2nd or 3rd harmonic beam reflective surfaces and contains a 2nd or 3rd harmonic generator, preferably a harmonic nonlinear crystal. The beam from the fundamental cavity is directed into the harmonic cavity to incident on the harmonic nonlinear crystal for converting at least a portion of the fundamental beam to a harmonic beam. An Nth (N>2) harmonic generator, preferably an Nth harmonic nonlinear crystal, is in optical communication with the 2nd or 3rd harmonic nonlinear crystal for providing an Nth harmonic output.
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