Scanning moire and phase shifting with time delay and integration imaging

Scanning moire is generated by undersampling of a phase-modulated grating pattern. In projection profilometry the scanning moire pattern represents equal height and depth contours on a test object. By use of time delay and integration (TDI) imaging, it is possible to generate an on-line scanning moire pattern from the complete periphery of a rotating cylindrical object. For automated phase and profile unwrapping from scanning moire fringes, phase-shifting interferometry techniques are most desirable. However, lack of spatial information in the undersampled scanning moire fringes introduces serious errors in phase unwrapping. We report a method that uses oversupply of data to balance the effect of undersampling. This oversupply is achieved with a TDI feature that permits programmable image magnification in the scanning direction. (C) 1997 Optical Society of America.