Development of Simultaneous Confocal Full-field Surface Profilometry for Automatic Optical Inspection (AOI)

摘要

A simultaneous confocal full field 3-D surface profilometer using digital structured fringe projection is presented in the article. Using digital micromirror device (DMD) moire projection, a digital fringe pattern is developed for lateral scanning with high spatial resolution and measurement efficiency. Four conjugate image sensing modules are configured at four different designated focusing positions, which are controlled by four glass substrates with various thicknesses. A depth-focus response curve can be established by achieving simultaneous vertical scanning of full-field surface profilometry. A standard step height has been measured to attest the measurement accuracy and feasibility of the developed approach. The depth measurement resolution can reach up to 0.1μm and the maximum measurement error was verified to be within 7% of the overall measuring height size. The measurement efficiency can be significantly improved for online automatic optical inspection (AOI).