| 摘要 |
PURPOSE:To restrain a rise in the noise level of a first laser beam and to radiate a second laser beam without being affected by a very small change in the temperature and the current of the second laser by a method wherein the distance between the radiant face and the reflecting face of the first laser beam is set to a distance at which the coherence of the first laser becomes lower than a prescribed level. CONSTITUTION:A laser diode 1, for excitation use, which is arranged at the end of a heat sink 2 generates a laser beam for excitation use and it makes the laser beam incident on a lens 3. The lens 3 condenses the laser beam for excitation use and it makes the laser beam incident on a resonator 4. The resonator 4 integrates a quarter-wave plate 5, a laser medium 6 and a nonlinear optical crystal element 7. It is arranged that the forward and backward optical path length between the radiant face 1a of the laser diode 1 and the reflecting face 5a or 5b of the quarter-wave plate 5 satisfies a relationship by which reflected light is returned to the laser diode 1 in a position where coherence is lowered. Thereby, it is possible to reduce a noise in the low frequency of a laser beam radiated by a standing wave-type resonator. |
