Streifende-Inzidenz-Interferometrie mit diffraktiven Elementen fuer die Formmessung von Mantelflaechen stabfoermiger Objekte II: Experimente und Fehlerdiskussion

摘要

Dies ist Teil II des zweiteiligen Artikels (Teil I: siehe tm 1/2000) ueber die Streifende-Inzidenz-Interferometrie. Hier werden die Auswertemethoden, Messbeispiele fuer technische Objekte wie (1) Ebene, (2) Zylinder, (3) mathematisch konvexe Objekte und (4) allgemeine Meridiankurven von Staeben, die auftretenden systematischen Fehler aufgrund des Prinzips aber auch aufgrund der Herstellgenauigkeit lithographischer Maschinen und schliesslich auch noch Erweiterungen in den mittleren IR-Bereich diskutiert. Um die Uebersicht zu erleichtern, sind die Kapitel fortlaufend nummeriert, beginnend mit Kapitel 9. We report on the experimental verification of the principles given in part I (see tm issue 1/2000) concerning grazing incidence interferometry using diffractive optical elements as beam splitters and shaper. The experimental verification comprises three rod shapes: (1) plane surface, (2) cylinder, and (3) a general convex rod shape. For all rod shapes suitable functionals for the removal of alignment terms have been programmed and verified. The repeatability is of the order of 1/200 of the effective wavelength which is for 10 μm pitch of the order of 0.025 μm. The software developed for the phase shift evaluation runs under Windows NT and provides all useful representations of surface parameters like cross sections, pseudo-3D-plots of the unrolled mantle surface etc. In addition peak to valley and rms-figures are calculated. Beside the stochastic errors also systematic errors occur due to the special transmitted light geometry involving an inversion of one of the wavefronts at a central meridian of the rodshaped object under test. The error budget and conditions to avoid the main systematic error contributions are discussed. The basic concept can also be transferred into the mid-IR-region. For a verification of the principle and the demonstration of the advantages of this transition into the IR a He-Ne-wavelength at 3.39 μm together with a PtSi-array-camera have been used. Results of such measurements are presented.