Three-dimensional shape measurement of a diffusing surface by use of a femtosecond amplifying optical Kerr gate

We propose a system for three-dimensional (3D) shape measurement of a diffusing surface by use of a previously developed femtosecond amplifying optical Kerr gate (fs-amp OKG). The system has an opening time of 459 fs and a maximum transmittance of 185%. It also provides good 3D imaging performance: a transverse imaging resolution of 70 mum, a depth resolution of 100 mum, and a positioning accuracy of 5.9 mum in depth. It is found that the optical Kerr effect and the amplification process in the fs-amp OKG do not cause the quality of a time-resolved image to deteriorate. We prove the effectiveness of the proposed system by measuring the shapes of completely diffusing objects with stepped and spherical surfaces.