Fabrication of digital sinusoidal gratings and precisely controlled diffusive flats and their application to calibration-based highly accurate phase-shifting projected fringe profilometry are presented. The main advantages of using digital sinusoidal gratings are (1) high geometrical accuracy (< 1 μm); (2) high contrast ratio; and (3) very low high-order harmonic distortion. In addition, a high-quality diffusive flat with precisely controlled lateral correlation length, fabricated by VLSI processes, offers a good calibration standard. It is found that, by applying these two components to the calibration-based phase-shifting projected fringe profilometry, absolute 3-D surface profile measurement accuracy on the order of microns can be achieved.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics