Abstract: A method and apparatus for extracting two-dimensional image shapes from image data on a pixel array. The method comprises the steps of selecting intensity vs. pixel information in a plurality of directions in the vicinity of an edge of the image shape, and recognizing scans with sufficient contrast as containing edge information. Acceptable scans are subjected to an edge detection algorithm, the edge location is detected, and a locus of points is generated, from the detected edge values, that define the two-dimensional shape of the image. The edge detection algorithm may be a user defined edge detection algorithm that is tailored to the application. Also, in a preferred embodiment, the selecting step includes the step of selecting intensity vs. pixel information in at least four directions, and the plurality of directions are angularly spaced apart at least about 22 degrees. With one embodiment, one of these directions may be normal to an approximate edge location.

Abstract: A method for nondestructively determining the line profile or topographical cross-section of repeating lines on a substrate is provided, including line thickness, line width, and the shape of the line edge. A substrate having a repeating structure, such as a grating, is illuminated with broad-band radiation. Diffracted radiation is collected, measured, and recorded as a function of wavelength to provide an intensity versus wavelength curve. An initial model of the line profile of the grating, a model of the broad band radiation shined on the grating, and a model of the interaction of the radiation with the model grating is provided to a data processing machine. The machine uses Maxwell's equations to calculate a model diffracted intensity versus wavelength curve, and the measured intensity curve is then compared with this modeled intensity versus wavelength curve.