Investigation of Angle Measurement Based on Direct Third Harmonic Generation in Centrosymmetric Crystals

This paper proposed angle measurement methods based on direct third harmonic generation (THG) in centrosymmetric crystals. The principles of the intensity-dependent and wavelength-dependent were illustrated. In this study, three prospective crystals two different phase-matching types investigated a wavelength range from 900 nm to 2500 nm. For method, dispersion-less was found 1700 2000 for α-BBO calcite. Compared with rutile, calcite had relatively better performance sensitivity calculation. method considered dispersive around 1560 results suggested that also suitable measurement. addition, effects focusing parameters simulation, optimized focal length (f = 100 mm) focused position (in center crystal) determined.