A novel surface-measurement technique uses a reflective Shack-Hartmann wavefront sensor to scan optical surfaces and then uses software to stitch individual measurements together, resulting in high-resolution accuracy and high dynamic range with the ability to scale up or down to any size optic. The competing requirements of accuracy, spatial resolution, dynamic range, and large field of view limit many optical measurement techniques. To address these limitations, WaveFront Sciences has developed a technique that scans and stitches together sub-aperture data to enable surface topology measurements with high resolution, accuracy, and dynamic range, along with a large field of view determined by the scan range. Using a Shack-Hartmann wavefront sensor that measures the reflective optical phase from a light beam incident on the surface, the optical phase can be directly related to the surface-height information that is mapped in two dimensions across the surface. After scanning the surface--either by a lateral scan of the reflective wavefront sensor system across the surface or by keeping the sensor fixed and laterally translating the surface relative to the sensor--individual measurements are stitched together by sophisticated software algorithms that scale over a range of dimensions from 100-mm wafers up to mirrors larger than 1 m in diameter.
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