Spatially resolved scattering metrology to quantify losses induced by contamination and defects
| Autor: | Bolliand, Adrien, Zerrad, Myriam, Lequime, Michel, Amra, Claude |
|---|---|
| Přispěvatelé: | CONCEPT (CONCEPT), Institut FRESNEL (FRESNEL), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | ICSO 2022 ICSO 2022, Oct 2022, Dubrovnik, Croatia |
| Popis: | International audience; In less than 20 years, extraordinary progress has been made on the design and manufacturing of planar optical components, especially in terms of minimizing light scattering (a few 10^-6 of the incident flux). This progress is closely linked to polishing techniques, which allow to obtain, on amorphous substrates, roughness lower than a fraction of nanometer in the optical frequency window. Moreover, with modern filter manufacturing technologies, the roughness of the substrate is reproduced almost identically by each of the thin layers constituting the stack.However, at this level of qualification, new problems and concerns arise, in particular the presence of localized defects in the component. These defects are of sub-micron size and appear during the manufacturing of the filters. Their density is low (less than one defect for a 100 micrometers diameter disk), so for conventional components, their contribution can be neglected. However, for Space optics and gravitational waves detection, the impact of these isolated defects can become dominant in the light scattering process and its accurate quantification remains a challenge. To address this problematic, the CONCEPT Group of the Institut Fresnel developed a SPatially and Angulary Resolved Scatterometry Equipment (SPARSE). The principle of the instrument is based on the coupling of imaging abilities with a scatterometer. It is designed to record up to 440 thousand BRDF with a single measurement on a one inch diameter component. A beam shaping arm is added to tailor the illumination to the shape of the component and to offer the capability to “turn off” defects in order to increase the detectivity. SPARSE allows the measurement of scattering level as low as 10^-8 sr^-1$ and the data processing is designed to discriminate and quantify the weight of localized defects, contamination, scratches and roughness in the scattering budIn less than 20 years, extraordinary progress has been made on the design and manufacturing of planar optical components, especially in terms of minimizing light scattering (a few 10^-6 of the incident flux). This progress is closely linked to polishing techniques, which allow to obtain, on amorphous substrates, roughness lower than a fraction of nanometer in the optical frequency window. Moreover, with modern filter manufacturing technologies, the roughness of the substrate is reproduced almost identically by each of the thin layers constituting the stack.However, at this level of qualification, new problems and concerns arise, in particular the presence of localized defects in the component. These defects are of sub-micron size and appear during the manufacturing of the filters. Their density is low (less than one defect for a 100 micrometers diameter disk), so for conventional components, their contribution can be neglected. However, for Space optics and gravitational waves detection, the impact of these isolated defects can become dominant in the light scattering process and its accurate quantification remains a challenge. To address this problematic, the CONCEPT Group of the Institut Fresnel developed a SPatially and Angulary Resolved Scatterometry Equipment (SPARSE). The principle of the instrument is based on the coupling of imaging abilities with a scatterometer. It is designed to record up to 440 thousand BRDF with a single measurement on a one inch diameter component. A beam shaping arm is added to tailor the illumination to the shape of the component and to offer the capability to “turn off” defects in order to increase the detectivity. SPARSE allows the measurement of scattering level as low as 10^-8 sr^-1 and the data processing is designed to discriminate and quantify the weight of localized defects, contamination, scratches and roughness in the scattering budget. We propose in this paper a detailed description of the set-up with its metrological qualification and some examples of measurements performed on representative Space Optics.get. We propose in this paper a detailed description of the set-up with its metrological qualification and some examples of measurements performed on representative Space Optics. |
| Databáze: | OpenAIRE |
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