| 摘要 |
PROBLEM TO BE SOLVED: To reduce a pulse width, improve efficiency, facilitate handling, improve reproducibility and stability, prevent a wavelength conversion crystal from being damaged, and miniaturize a device by forming a mirror at a side near the wavelength conversion crystal for composing a stable resonator with a convex mirror. SOLUTION: The curvature of a resonator mirror 1 with a high reflection factor for a fundamental wave laser beam and a resonator mirror 7 with a high reflection factor for a second harmonic laser beam and the fundamental wave laser beam is of convex surface, and a wavelength conversion crystal 4 for generating second harmonic is subjected to phase matching by changing its angle and temperature for changing the refractive index of the wavelength conversion crystal. The wavelength conversion crystal 4 is placed near the resonator mirror 4 whose curvature is of convex surface. Then, by appropriately selecting the curvature of a convex mirror and the distance between mirrors, the shape of a beam mode becomes that without any beam waist in a resonator, thus reducing the length of the resonator while nearly identically maintaining the diameter of the beam mode at a stable oscillation region in excitation intensity.
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