Assessing surface imperfections of freeforms using a robotic light scattering sensor

Herffurth, Tobias; Trost, Marcus; Beier, Matthias; Steinkopf, Ralf; Heidler, Nils; Pertermann, Tom; Schröder, Sven

doi:10.1117/1.oe.58.9.092609

Cited by 4 publications

(4 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The performance of optical instruments might quickly be limited by particular or molecular organic contamination (PAC, MOC) and surface defects. Beside surface roughness, these imperfections are primary origins of light scattering [1][2][3][4][5][6] that causes a reduced imaging contrast or a loss of throughput. In particular for supersmooth surfaces or thin film coatings, as those applied in space or lithography industry, even lowest imperfections levels might be performance limiting.…”

Section: Motivationmentioning

confidence: 99%

“…However, imperfections on optical components are unavoidable and, therefore, budgeting and characterization becomes mandatory. On the other hand, the induced light scattering is an ideal, highly sensitive, fast, and flexible characterization tool for imperfection analysis [2][3][4][5][6] even on extended freeform surfaces [5].…”

Section: Motivationmentioning

confidence: 99%

“…For a rapid full surface analysis of particles and defects on extended surfaces, a compact hybrid sensor with a CMOS detector matrix for ARS measurement [3] and a microscope for geometrical feature analysis was developed. This sensor is traced over sample surfaces using a robotic handling system [5] that enables the characterization of freeform components. Hence, the resulting mapping data can be analyzed for local rmsroughness, homogeneity, local and averaged 3D-ARS data, or PAC by evaluating the scattering or feature geometry data.…”

Section: Sensor For Freeform Surfaces Assessmentmentioning

confidence: 99%

See 2 more Smart Citations

Light Scattering from Contamination and Defects - Measurement, Analysis, and Modelling

et al. 2022

View full text Add to dashboard Cite

Light scattering induced by contamination and defects on optical components can quickly limit the component’s performance. Therefore, imperfection analysis and budgeting are mandatory - but also challenging tasks. On the other hand, imperfections can be elegantly characterized using efficient, robust and non-contact light scattering techniques. This will be demonstrated in this contribution for area covering measurement approaches using laboratory instruments with highest sensitivity as well as elaborated sensor systems that are best suited for extended freeform surfaces. Moreover, the measurement results are used to derive practical imperfection scattering data and models that serve as input to model and predict the imperfection induced scattering on optical system level.

show abstract

Section: Motivationmentioning

confidence: 99%

Section: Motivationmentioning

confidence: 99%

Section: Sensor For Freeform Surfaces Assessmentmentioning

confidence: 99%

See 1 more Smart Citation

Light Scattering from Contamination and Defects - Measurement, Analysis, and Modelling

et al. 2022

View full text Add to dashboard Cite

show abstract

“…At each measurement position, an image of the angle resolved scattering (ARS) 33,35 was recorded from which the local surface roughness in the spatial frequency range of about f ¼ 0.03 to 0.3 μm −1 was calculated using Rayleigh-Rice theory. 35 Although the surface is coated with a protection layer, the calculations were performed using a single surface approximation of the protective coating. 36 The roughness mapping reveals an increasing roughness from the lower left with an average of about 0.5 nm to the top right with an average roughness of about 1 nm.…”

Section: Surface Metrology and Straylightmentioning

confidence: 99%

Design, additive manufacturing, processing, and characterization of metal mirror made of aluminum silicon alloy for space applications

et al. 2019

Self Cite

View full text Add to dashboard Cite

Metal mirrors are used for spaceborne optical systems, such as telescopes and spectrometers. In addition to the optical performance, the mechanical needs and the mass restrictions are important aspects during the design and manufacturing process. Using the additive manufacturing process, optimized internal lightweight structures are realized to reduce the weight of the system while keeping the mechanical stability. A mass reduction of ≈60.5% is achieved. Using the aluminum silicon alloy AlSi40, the thermal mismatch of the mirror base body to a necessary electroless nickel-polishing layer is minimized. Based on an exemplary mirror design, the optimization of the interior lightweight structure is described, followed by the manufacturing process from additive manufacturing to diamond turning, plating, and polishing. Finally, the results of surface metrology and light scattering measurements are presented. A final form deviation below 80 nm p: − v: and a roughness of ∼1 nm rms could be demonstrated.

show abstract

Light Scattering of optical Components and their Imperfections: Measurement, Modelling, and System Analysis

Herffurth,

Mühlig,

Munser

et al. 2024

EPJ Web Conf.

View full text Add to dashboard Cite

Light scattering in optical systems is caused by various imperfections such as surface roughness, bulk inhomogeneity, contamination, and ghost light beam paths. Control of these scattering sources is crucial, particularly for high-precision optical components, and involves both measurement and modelling from the design phase through fabrication to system integration. Recent developments at Fraunhofer IOF have led to advanced instruments for characterization of both optical components and system. Moreover Light scattering measurements provide not only analysis capabilities but also critical data for optimizing fabrication processes by identifying scattering contributors. Results and applications of these techniques and tools will be presented, highlighting their impact on optimizing optical system fabrication.

show abstract

Assessing surface imperfections of freeforms using a robotic light scattering sensor

Cited by 4 publications

References 28 publications

Light Scattering from Contamination and Defects - Measurement, Analysis, and Modelling

Light Scattering from Contamination and Defects - Measurement, Analysis, and Modelling

Design, additive manufacturing, processing, and characterization of metal mirror made of aluminum silicon alloy for space applications

Light Scattering of optical Components and their Imperfections: Measurement, Modelling, and System Analysis

Contact Info

Product

Resources

About