Universal Fourier optics model for virtual coherence scanning interferometers

Peter Lehmann; Tobias Pahl; Jörg Riebeling

doi:10.1117/12.2673292

10 August 2023 Universal Fourier optics model for virtual coherence scanning interferometers

Peter Lehmann, Tobias Pahl, Jörg Riebeling

Proceedings Volume 12619, Modeling Aspects in Optical Metrology IX; 126190O (2023) https://doi.org/10.1117/12.2673292
Event: SPIE Optical Metrology, 2023, Munich, Germany

Abstract

Optical surface topography measurements sometimes suffer from systematic errors. In order to predict such deviations, modeling of optical profilers is a substantial part of the European project TracOptic (Traceable Optics). Within the framework of this project, we recently developed the UFO (Universal Fourier Optics) model, which simulates virtual CSI measurements of surface topographies that fulfill the requirements of the scalar Kirchhoff approximation. The model enables a fast computation of ‘measured’ surface topographies as it is based on discrete Fourier transforms. It treats the surface under investigation as a two-dimensional phase object assuming a linear dependence of the interference phase on surface height and axial spatial frequency. The scattered light field is transferred to the Fourier domain and multiplied by a partial two-dimensional transfer function (TF) representing a horizontal cross section of the three-dimensional TF at a certain axial spatial frequency or evaluation wavelength, respectively. The TF includes parameters of the interference microscope and the reference field distribution. Inverse Fourier transform enables the reconstruction of the phase object. The coherence peak position of an interference signal results from numerical differentiation with respect to the axial spatial frequency and is generally used to overcome the 2π ambiguity of the phase profile. Parameters affecting final results of reconstructed surface topographies are the central wavelength and the spectral bandwidth of the illuminating light as well as the numerical aperture of the objective lens and the chosen evaluation wavelength. We discuss results of the UFO model with respect to the prediction of systematic deviations of measured surface topographies.

Conference Presentation

Citation Download Citation

Peter Lehmann, Tobias Pahl, and Jörg Riebeling "Universal Fourier optics model for virtual coherence scanning interferometers", Proc. SPIE 12619, Modeling Aspects in Optical Metrology IX, 126190O (10 August 2023); https://doi.org/10.1117/12.2673292

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available