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Layer thickness measurement of technically anodised aluminium surfaces by using goniometric scattered light

Geisler Tobias, Manns Martin

Metrology and Measurement Systems

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2021

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Vol. 28, nr 2

371--382

EN

In recent years, scattered light measurement technology has developed into a common method for measuring roughness, form and waviness on precision machined surfaces. Meanwhile, the application for the material structure evaluation of electrolytically anodized surfaces has also been considered. In this context, we present a novel approach to layer thickness measurement of naturally anodised aluminium surfaces. Our approach is based on the reflection intensity of the light beam, which penetrates the oxide layer and is reflected back from the surface as well as from the layer base. In the approach, a model for estimating reflection intensity I from the absorption coefficient is employed. The methodology is tested by comparing results to a layer thickness evaluation using metallographic preparation. Based on the proposed approach, we are able to measure intervals of layer thicknesses on naturally anodized aluminium surfaces without contact.

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Pattern Recognition of Rough Surfaces by Using Goniometric Scattered Light

Geisler T., Kolb A.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 1

33--46

EN

Nowadays, most techniques for evaluating rough metal surfaces are based on tactile or confocal measurement procedures. However, these technologies have disadvantages in respect to measuring speeds, resistance to vibration, impact and dust. In this paper we present a novel surface measurement approach, which uses the scattering light technology. Our approach enhances the state-of-the-art scattering light-based surface measurement methodology in both the detector setup and evaluation of the raw intensity values acquired by the scattered light device. The main goal in optimizing the measurement setup is to capture scattering parameters for rough surfaces in a range greater than 10 μm based on an enlarged detector array. Regarding the evaluation, we propose a pattern recognition approach which maps the reflection intensity I back to material structures and the tenpoint mean roughness Rz , the golden standard in tactile roughness characterization. Based on this approach, we are able to classify rough surface deviations like stripes using a simple but robust thresholding. In order to demonstrate the generality of our approach, we evaluate our approach using two rather different materials, i.e. brushed stainless steel and anodized aluminium.

3

Realizacja układu detekcyjnego do pomiarów rozpraszających próbek odbiciowych i transmisyjnych na bazie spektrometru Cary 5

Rafałowski M.

Zeszyty Naukowe Politechniki Białostockiej. Elektryka

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2002

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Z. 16

193-200

PL

Układ spektrometru "Cary 5" w wersji oryginalnej realizuje pomiary próbek transmisyjnych w zakresie spektralnym 200¸3300 nm na zasadzie detekcji porównawczej przełączanych sekwencyjnie wiązek: odniesienia i pomiarowej. Wskazuje to na konieczność utrzymania symetrii konfiguracji geometrycznej torów: pomiarowego i od odniesienia na całej drodze światła od źródła promieniowania do detektora. Celem modyfikacji jest umożliwienie pomiaru próbek rozpraszających o średnicy do 20 mm. Wykluczono modyfikacje naruszające oryginalne możliwości pomiarowe przyrządu. W celu oświetlenia całej powierzchni próbki badanej zastosowano układ optyczny zawierający zwierciadła toryczne (o odpowiednio dobranych mocach cylindrycznych w przekrojach wzajemnie prostopadłych). Zapewnia to odwzorowanie (astygmatycznych) obrazów szczeliny spektrometrycznej we wnętrzu kuli całkującej. W pracy przedstawiono dyskusję oraz proponowane rozwiązanie techniczne problemu.

EN

The original configuration of the Cary 5 spectrometer realize the measurements of the light, transmitted by no scattering samples in spectral range from 200 nm to 3300 nm on the principle of comparison sequently switched: reference beam and measured beam of light. The symmetry of both trajectories (of reference and measurement beams) is highly recommended. The goal of here-discussed modification of the system is to make possible to measure of scattering samples diameter to 20 mm. The violation of the original measurement characteristics of the apparatus is to exclude. To illuminate of the whole sample area the optical system of toroidal mirrors (with appropriate choice of the cylindrical power in two perpendicular cross-sections) is applied. This ensures the optical imaging (astigmatic) of the slit in the integrating sphere to optimize the illumination of the sample. The major aspects of the measurement, the discussion and the technical solution are shown.