Patent ID: 8553734

Claim:
A system comprising: a first nonlinear crystal, arranged to receive a first incident laser beam having a first wavelength λ 1 , and operable to generate, by frequency doubling of the first laser beam, a second laser beam having a second wavelength λ 2 , wherein the second laser beam propagates collinearly with the first laser beam; a second nonlinear crystal, arranged to receive the first laser beam and the second laser beam, and operable to generate, by frequency mixing of the first laser beam and the second laser beam, a third laser beam having a third wavelength λ 3 ; and one or more lenses arranged between the first nonlinear crystal and the second nonlinear crystal, wherein the one or more lenses are operable to spatially separate the first laser beam and the second laser beam from one another prior to the first laser beam and the second laser beam being incident on the second nonlinear crystal, wherein the first laser beam and the second laser beam propagate through the one or more lenses at an offset with respect to an optical axis of the one or more lenses, or at an angle with respect to the optical axis of the one or more lenses, or at an offset and at an angle with respect to the optical axis of the one or more lenses.