• SHIRLEY AND HALLERMAN Nonconventional 3D Imaging Using Wavelength-Dependent Speckle Nonconventional 3D Imaging Using Wavelength-Dependent Speckle

■ We describe a technique known as speckle-pattern sampling for noncontact measurement of an object’s surface contour. In this technique, the object is flood illuminated by a tunable laser, and the wavelength and spatial dependence of the resulting speckle pattern in the scattered light are Fourier analyzed to yield a 3D image of the scattering surface. The theoretical analysis includes a treatment of image aberrations and near-field effects. The technique is demonstrated with laboratory measurements that show good agreement with results from standard contact-based measurements. Range resolutions of better than 10 μm are achieved. This technique has two principal advantages over many other noncontact methods: the range resolution does not degrade as the distance to the object increases, and the source and receiver lie in the same direction so that the image is not affected by shadowing. This article describes a nonconventional 3D imaging technique based on the wavelength dependence of laser speckle. The technolog