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

Wei-Hung Su,Bo Wang,Zhiwen Liu,Shizhuo Yin,Kebin Shi,Karl Reichard

doi:10.1364/opex.13.001025

Abstract

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.

Highlights

Projected fringe profilometry is one of the most effective methods to measure the 3D surface profiles of rough engineering surfaces [1,2,3]
To maintain the advantages and eliminate the limitation of the laser sources used in the projected fringe profilometry, in this paper, we investigate the use of a supercontinuum light generated by launching ultra short laser pulses into a highly nonlinear photonic crystal fibers in the projected fringe profilometry [13,14,15,16]
We investigated a unique projected fringe profilometry based on the supercontinuum light illumination

Summary

Introduction

Projected fringe profilometry is one of the most effective methods to measure the 3D surface profiles of rough engineering surfaces [1,2,3]. Profile measurements by phase-shifting projected fringe methods are commonly used either in a comparative mode, in which a surface is compared to another surface and the difference is measured; or in an absolute mode, in which the depth of a single surface is measured. Both modes require a sinusoidal fringe pattern projected onto the inspected surface in order to demodulate the distorted fringe values into the corresponding depths. It is found that a highly accurate projected fringe profilometer can be built by applying the supercontinuum light in the system

Depth of field under supercontinuum light illumination

Conclusion