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Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

Journal Article · · Nuclear Instruments and Methods in Physics Research, Section A
OSTI ID:988781
A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in papers Yashchuk et al. (2007), Yashchuk et al. (2008) is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one-dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high performance of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two-dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the Micromap{trademark}-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.
Research Organization:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Organization:
Doe - Office Of Science
DOE Contract Number:
AC02-98CH10886
OSTI ID:
988781
Report Number(s):
BNL--93836-2010-JA; KA-11
Journal Information:
Nuclear Instruments and Methods in Physics Research, Section A, Journal Name: Nuclear Instruments and Methods in Physics Research, Section A Journal Issue: 2-3 Vol. 616; ISSN NIMAER; ISSN 0168-9002
Country of Publication:
United States
Language:
English