| US 7,539,222 B2 | ||
| Method of operating laser light source | ||
| Kazuto Matsuki, Tokyo (Japan) | ||
| Assigned to Advanced Mask Inspection Technology Inc., Yokohama-shi (Japan) | ||
| Filed on Apr. 04, 2006, as Appl. No. 11/278,637. | ||
| Claims priority of application No. 2005-281108 (JP), filed on Sep. 28, 2005. | ||
| Prior Publication US 2007/0071042 A1, Mar. 29, 2007 | ||
| Int. Cl. H01S 3/10 (2006.01) | ||
| U.S. Cl. 372—21 [372/22] | 5 Claims |
| 1. A method of operating a laser light source including a wavelength conversion device in which two wavelength laser beams
are input to a nonlinear crystal to output a sum frequency wavelength, the method comprising:
measuring light intensity of the sum frequency wavelength by a light sensitive sensor installed on an optical axis of the
output sum frequency wavelength in an operation mode,
periodically ceasing the operation mode and entering a judgment mode including,
inputting only one wavelength laser beam of the two wavelength laser beams to the nonlinear crystal,
measuring scattered light intensity of the one wavelength laser beam by the light sensitive sensor, and
judging a damage state of the nonlinear crystal based on a measurement value obtained by the measuring.
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