Coherent light of one color will form laser speckle upon reflection from a rough object. This laser speckle provides information about the shape of an object. Further information can be obtained if two colors are used, and if the colors are sufficiently close in wavelength that the interference is also measurable. The two speckle patterns and the interference can be shown to provide the minimum information sufficient to form a band-limited image of the object using a root-matching technique described herein. This root-matching technique is performed in the far-field or object plane. This technique is relatively slow and sensitive to noise, and so is supplemented with a technique that minimizes ror in the pupil plane. A hybrid technique that combines the two approaches is shown to reproduce images effectively with reasonable computation time.
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