| 摘要 |
A laser beam generator includes first and second mirrors, a laser light source, a laser medium, a non-linear optical crystal element and a birefringent element. The laser light source generates a pumping light beam. The laser medium, arranged between the first and second mirrors, is irradiated with the pumping light beam via one of the mirrors to generate a fundamental laser beam based on the pumping light beam. The non-linear optical crystal element is arranged between the first and second mirrors to generate a second harmonic laser beam under the type II phase matching as the fundamental laser beam from the laser medium is passed through it in resonant oscillation. The birefringent element has its one surface at a pumping light beam inlet side coated with a high reflectance coating and has its opposite surface parallel to it with a nonreflective coating, The birefringent element is set so that its optical axis is inclined at a predetermined azimuth angle with respect to the crystal axis of the non-linear optical crystal element. The surface of the birefringent element coated with a high reflectance coating constitutes one of the first or second mirrors.
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