A large-depth-of-field projected fringe profilometry using supercontinuum light illumination

In this paper, a large-depth-of-field projected fringe profilometry using a supercontinuum light source generated by launching femto second laser pulses into a highly nonlinear photonic crystal fiber is presented. Since the supercontinuum light has high spatial coherence and a broad spectral range (from UV to near infrared), a high power (hundreds of mW) point white light source can be employed to generate modulated fringe patterns, which offers following major advantages: (1) large-depth-of-field, (2) ease of calibration, and (3) little speckle noise (a major problem for the laser system). Thus, a highly accurate, large-depth-of-field projected fringe profilometer can be realized. Both the theoretical description and experimental demonstration are provided.