Patent ID: 7110426

Claim:
A laser beam generating apparatus comprising: a. a gallium nitride semiconductor laser that produces a laser beam with a first wavelength, b. an external resonator comprising a nonlinear optical crystal, wherein; the nonlinear optical crystal produces a Type I phase matching angle and the nonlinear crystal is a barium borate (β-BaB 2 O 4 ), and the laser beam produced by the semiconductor laser is directed by the external resonator so as to pass through the nonlinear optical crystal, to generate an ultraviolet beam having a second wavelength shorter than the first wavelength, c. a controller operatively configured and associated with the external resonator, and d. an effective nonlinear constant expressed by a first term containing an effective non-linear constant d 22 of the barium borate crystal and a second term containing an effective nonlinear constant d 31 of the barium borate crystal, wherein the phase matching angle is not 90°, and wherein the first and second terms are either both positive or both negative.