Key Technologies in Image Processing of Interferogram

Interferogram processing is one of main techniques in optical interferometry metrology. Modern interferometry for thin-film thickness has the advantages of noncontact and high accuracy, etc. Interferogram processing is important Step of interferometry. This article is the sum-up about the key technology of interferogram processing in interferometry, it reduce key technology of interferogram processing to three steps: removing the noise, edge detection, region spreading and phase unwrapping. Interferogram processing can be realized by using software developed by the key technologies. Then getting surface of the measured material object, thus the measured material object is measured automatically. In this paper, the thin-film thickness is determined by the key technologies, setting the results of this method against results from ZYGO, the PV error and RMS maximum error are 0.0364λ and 0.002λ respectively. Although single interferogram was processed in this study, a phase distribution with high accuracy was achieved.

Microrelief Measurements for White-Light Interferometer with Adaptive Algorithm Interferogram Processing

The problem of reducing measurement errors of surface microrelief with nonuniform scattering properties using white-light interferometer was discussed. Adaptive algorithm of thresholding which allows us to set optimal threshold in every point of measuring surface was proposed. Application of this algorithm of threshold choice allows increasing dynamical range of interference detection more than in 10 times. The dependences of scanning interferometer resolution on differentional interferogram thresholding have been discussed.