METHOD FOR THREE-DIMENSIONAL IMAGING USING MULTI-PHASE STRUCTURED LIGHT

A method for mapping height of a feature upon a test surface is provided. The method includes projecting patterned illumination upon the feature, the patterned illumination having a plurality of distinct fringe periods. A first image of the feature is acquired while the patterned illumination is projected upon the feature. Relative movement is then generated between a sensor and the feature to cause relative displacement of a fraction of a field of view of a detector, the fraction being equal to about an inverse of the number of distinct regions of a reticle generating the pattern. Then, a second image of the feature is acquired while the patterned illumination is projected upon the feature. The height map is generated based, at least, upon the first and second images.