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Proceedings Paper

Integrating optical fabrication and metrology into the optical design process
Author(s): James E. Harvey
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Paper Abstract

Image degradation due to scattered radiation from residual optical fabrication errors is a serious problem in many short wavelength (X-ray/EUV) imaging systems. Most commercially-available image analysis codes (ZEMAX, Code V, ASAP, FRED, etc.) currently require the scatter behavior (BSDF data) to be provided as input in order to calculate the image quality of such systems. This BSDF data is difficult to measure and rarely available for the operational wavelengths of interest. Since the smooth-surface approximation is often not satisfied at these short wavelengths, the classical Rayleigh-Rice expression that indicates the BRDF is directly proportional to the surface PSD cannot be used to calculate BRDFs from surface metrology data for even slightly rough surfaces. However, an FFTLog numerical Hankel transform algorithm enables the practical use of the computationally intensive Generalized Harvey-Shack (GHS) surface scatter theory [1] to calculate BRDFs from surface PSDs for increasingly short wavelengths that violate the smooth surface approximation implicit in the Rayleigh-Rice surface scatter theory [2-3]. The recent numerical validation [4] of the GHS theory (a generalized linear systems formulation of surface scatter theory), and an analysis of image degradation due to surface scatter in the presence of aberrations [5] has provided credence to the development of a systems engineering analysis of image quality as degraded not only by diffraction effects and geometrical aberrations, but to scattering effects due to residual optical fabrication errors as well. These advances, combined with the continuing increase in computer speed, leave us poised to fully integrate optical metrology and fabrication into the optical design process.

Paper Details

Date Published: 17 December 2014
PDF: 11 pages
Proc. SPIE 9293, International Optical Design Conference 2014, 929328 (17 December 2014); doi: 10.1117/12.2075363
Show Author Affiliations
James E. Harvey, Photon Engineering LLC (United States)

Published in SPIE Proceedings Vol. 9293:
International Optical Design Conference 2014
Mariana Figueiro; Scott Lerner; Julius Muschaweck; John Rogers, Editor(s)

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