In a phase measuring interferometer (PMI), the interference pattern is focused on a charge coupled device (CCD) detector array and data points are sampled at the corresponding locations. In most commercially available systems, a zoom lens forms part of the optical configuration to suitably magnify the test optic to fill the detectors. Thus, the spatial sampling conditions are variable and determined by the magnification of the optical system and the size and spatial locations of the elements of the CCD. For accurate assessment of the spatial properties of the test optic (including power spectra for example), an accurate determination of the sampling conditions must be made. A computer simulation has been developed that enables an investigation of the theoretical capabilities of sub-pixel calibration resolution. In this paper we demonstrate how sub-pixel measurements may be achieved and indicate some of the factors that influence the outcome of the measurement.
Proceedings Title: Proceedings of 6th International Conference on Metrology and Properties of Engineering Surfaces
Conference Location: Kogan-Page, UK
Pub Type: Conferences