A hybrid focus method with multiple laser slits is newly proposed for the measurement of surface morphology with depth discontinuity, and it is based on the integration of DFD and DFF. Rough depth information is estimated through calibration tables which are constructed by DFD with multiple laser slits, and then DFF is applied to only each specific depth range using the rough depth information resulting from DFD. The proposed hybrid method gives more accurate results than DFD and DFF, and faster measurement than DFF in the vicinity of depth discontinuity. Its performance is verified through experiments of calibration blocks with sharp depth discontinuity.
