SCANNING MOIRE AND PHASE-SHIFTING WITH TIME-DELAY AND INTEGRATION IMAGING

Scanning moire is generated by undersampling of a phase-modulated grat ing pattern. In projection profilometry the scanning moire pattern rep resents equal height and depth contours on a test object. By use of ti me delay and integration (TDI) imaging, it is possible to generate an on-line scanning moire pattern from the complete periphery of a rotati ng 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 undersampl ed scanning moire fringes introduces serious errors in phase unwrappin g. We report a method that uses oversupply of data to balance the effe ct of undersampling. This oversupply is achieved with a TDI feature th at permits programmable image magnification in the scanning direction. (C) 1997 Optical Society of America.