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Proceedings Paper

Classification of optical surface properties and material recognition using mutlispectral BRDF data measured with a semihemispherical spectro-radiometer in VIS and NIR
Author(s): C. Hahlweg; H. Rothe
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Paper Abstract

A characterization of optical surface properties, especially in terms of the human visual perception, demands the use of BRDF data over a wide spectral range, at least over VIS. Further it could be interesting to perform a fast optical material recognition in industrial metrology. For the fast acquisition of large amounts of BRDF data over wavelength a small, fast and rugged spectro-radiometer without moving parts for angular resolution was developed. The semi- hemispherical measurement system is derived from a full-hemispherical set-up. It consists of a catadioptric system with an elliptical mirror mapping a semi-hemisphere onto a commercially available cartesian CMOS sensor with a dynamic range of 112dB. The sensor consists of 322096 pixels, producing an equivalent angle resolution. The system can take up to 53 semi-hemispherical BRDFs per second. The incoherent illumination is provided by a set of assorted LEDs. A radiometric measurement is possible over a wide spectral range from VIS to NIR over approximately 6.5 decades. Fast property characterization and material recognition from multivariate data in industrial applications demand appropriate analysis methods. As an analysis method a linear canonical discriminant analysis is applied to the data over angles and wavelength. In the paper measurement analysis results of the spectral signatures of various materials and test surfaces will be presented. Classification results and performances will be compared and discussed.

Paper Details

Date Published: 19 October 2005
PDF: 12 pages
Proc. SPIE 5965, Optical Fabrication, Testing, and Metrology II, 59650G (19 October 2005); doi: 10.1117/12.624838
Show Author Affiliations
C. Hahlweg, Helmut Schmidt Univ. (Germany)
H. Rothe, Helmut Schmidt Univ. (Germany)

Published in SPIE Proceedings Vol. 5965:
Optical Fabrication, Testing, and Metrology II
Angela Duparré; Roland Geyl; Lingli Wang, Editor(s)

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