Abstract: A nonlinear optical crystal (NLO) with a phase matching angle that is corrected with a source laser beam for harmonic conversion. The source laser only has to be within a wavelength range depending on the dispersion of the crystal while the crystal is tilted to the calculated expected conversion angle of the source laser as reference. The angle correction is accomplished with a parallel kinematic motion device to which a nonlinear crystal is mounted on a platform, to determine the wavelength- and temperature-specific angle with active laser alignment and subsequent precision resurfacing. The invented phase matching angle correction is applicable to any uniaxial and biaxial NLO crystals in a wide range of wavelengths, e.g., from far ultraviolet to visible to far infrared. It is of most value for NLO crystals of large walk-off and is applicable to any prior art frequency converting architectures.