Sensitivity analysis of tilted-wave interferometer asphere measurements using virtual experiments

Results of a Sensitivity Analysis for the Tilted-Wave Interferometer

“…It combines interferometric measurements with ray tracing and mathematical reconstruction procedures. The first results of a sensitivity analysis were given in [8]. The results support the feasibility of the basic TWI principle, and good reconstruction results were obtained for surfaces whose deviations from the design topography are described by Zernike polynomials.…”

“…Therefore, we extend the sensitivity analysis to surfaces whose deviation from their design topography no longer corresponds to a Zernike polynomial. We utilize a simulation environment that was developed at PTB for assessing optical measuring systems [8,9]. Reconstruction accuracies are then investigated in dependence on the variation of the specimen's topography and the measurement noise.…”

Traceability in interferometric form metrology

“…These assumptions were made to investigate the basic reconstruction principle in a first step. The influences of these assumptions have to be considered separately in some further steps (see, e.g., [11]). In this example, the reconstruction was performed using Zernike polynomial functions of the first 153 Zernike coefficients (j=1 to 153, n max = m max =16).…”

“…These measurement data are used to adapt the wavefront description in two reference planes of the optical system by solving yet another inverse problem [13]. The mathematical evaluation principle [11,14] is summarized below.…”

“…This task can typically be solved only by mathematical simulations of the complete measuring system. For this purpose, at PTB a simulation environment for optical surface metrology has been built, which is named SimOptDevice (Simulation for Optical Device) [11,12]. In a virtual experiment, a model of the measurement device is used and the measurement process is simulated (Fig.…”