ADVANCED EVALUATION TECHNIQUES IN INTERFEROMETRY

This chapter describes the advanced evaluation techniques in interferometry. The chapter discusses the methods that rely on the adjustment of a fringe pattern. The chapter examines the historically older interpolation methods where the phase information is extracted from the positions of the extrema. The chapter also discusses more general methods that deliver the phase in a more continuous form. A comparison of the different methods for phase evaluations necessitates a consideration of the error sources and limitations. These error sources for the case of phase sampling interferometry (PSI) have been discussed. The error causes are classified into statistical errors (measuring errors that can be diminished in their influence by averaging) and systematic errors (errors that cannot be quenched). The interferometers used in the assessment of test data are rather complex, thus, there is some necessity for calibration. The interferometer aberrations, even with ideal test samples, are caused by deviations of optical elements and to also by the state of adjustment. The chapter identifies the types of error sources—namely, environmental errors, errors that are dependent on the method, and errors typically encountered in interferometry. © 1990, Elsevier B.V. All rights reserved.