| 摘要 |
A topographical parameter measuring device and method utilizes a technique based on wave front reconstruction according to, e.g., Hartmann-Shack principles. The device includes a planar illuminator comprising a known array of illumination sources for projecting a light spot pattern onto a target surface. A CCD camera detects the positions of the reflected image spots in a manner similar to that in a Hartmann-Shack wave front sensor. The displacements of the light spots from reference coordinates are indicative of the slope of the surface at the plurality of sample points. A computational component is used to fit the slope data of a reference surface and the target surface to a polynomial, for example, a Zernike polynomial. The polynomial, properly weighted with the calculated coefficients, provides a continuous mapping of the elevation of the target surface. Based on the elevation data, all other topographical parameters including axial curvature, dioptric power, sphere, cylinder and others can be computed and displayed.
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