Abstract: Methods and apparatus for improving the efficiency of using optical sensors with component placement machines for the placement of components onto a circuit board. One of the improved methods involves the placement of a projection or notch at a selected position on the quill. The projection or notch is detected by the light based component sensor system on the placement head to indicate that it is safe to begin moving the placement head. A second improved method uses a constant, high angular velocity to rotate the component when the sensor is using the shadow cast by the body of the component to align the component. The use of a constant angular velocity allows for the correction for the rotation in determining the orientation to give very accurate results even though the velocity is relatively high.

Abstract: A computer implemented software device for estimating background tilt and offset is disclosed to preferably be adaptable to an optical measurement instrument wherein the estimated parameters are resolved to generate a reference plane to be subtracted from a height map of a phase profile. A set of histograms of heights is used to develop a merit function. A two-dimensional high speed iterative search is used to optimize the merit function to generate a reference plane coincident with the spatial tilt of the phase profile. The invention enables real-time measurement of substrate height for preferred use in high-speed image processing operations relating to circuit-board production lines.