Abstract: 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.