Large stable aluminum optics for aerospace applications

Vukobratovich, Daniel; Schaefer, John P.

doi:10.1117/12.892039

Cited by 33 publications

(23 citation statements)

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“…High-strength and low-weight large-scalable mirror optics can be designed. 4,5 Aluminum is lightweight, cheap, and readily formable with outstanding optical properties. Additionally, aluminum has a high-reflection coefficient even in the shortwave range.…”

Section: Introductionmentioning

confidence: 99%

Ion beam planarization of optical aluminum surfaces

Ulitschka

Bauer

Frost

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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For fabrication of high-performance mirror devices, technical aluminum alloys Al6061 or Al905 are widely used. The surface error topography after manufacturing by singlepoint diamond turning is applicable in the infrared spectral range. For increasing demands on the optical surface quality in the shortwave visible and ultraviolet spectral range, further improvement of the surface roughness is required. Hence, a promising alternative process to attain the required surface quality is evaluated. Within the ion beam planarization technique, a photoresist layer is deposited by conventional spin coating or spray coating technologies exhibiting an ultrasmooth surface. When removing the resist by reactive ion beam etch (RIBE) processing using nitrogen process gas, the ultrasmooth surface topography of the resist is transferred into the substrate. We optimized the photoresist thermal pretreatment to realize roughness preservation and a steady-state material removal rate during RIBE machining. The optimum preparation steps are explored based on roughness evaluation, chemical modification, and etch resistance of the negative photoresist. Reactive ion beam etching-based planarization is conducted on single-point diamond turned RSA Al905 and RSA Al6061 samples made of rapidly solidified aluminum (RSA) in a two-step process. The optimum process and the roughness evaluation are explored by topographic analysis applying a combination of white light interferometry and atomic force microscopy measurements. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Introductionmentioning

confidence: 99%

Ion beam planarization of optical aluminum surfaces

Ulitschka

Bauer

Frost

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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“…Technical aluminum alloy materials, such as AL6061, show an excellent shape stability, which is necessary for robust and durable optical devices. 1,2 Optical aluminum surfaces for use in the infrared spectral range are usually fabricated by single-point diamond turning (SPDT). [3][4][5] However, for short-wavelength applications in the visible (VIS) or even the ultraviolet (UV) range, the requirements on the optical surface quality increase.…”

Section: Introductionmentioning

confidence: 99%

“…6 However, by SPDT, a typical roughness of 2-to 3-nm rms is achievable. 1,7,8 An additional issue is the periodic turning marks with a pitch of 1 to 10 μm distance and up to a few ten nanometers in height. As a result, undesired diffraction effects appear in UV/VIS range applications.…”

Section: Introductionmentioning

confidence: 99%

Finishing of metal optics by ion beam technologies

et al. 2019

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Ultraprecise mirror devices show considerable potential with view to applications in the visible and the ultraviolet spectral ranges. Aluminum alloys gather good mechanical and excellent optical properties and thus they emerge as important mirror construction materials. However, ultraprecision machining and polishing of optical aluminum surfaces are challenging, which originates from the high chemical reactivity and the heterogeneous matrix structure. Recently, several ion beam-based techniques have been developed to qualify aluminum mirrors for short-wavelength applications. We give an overview of the state-of-the-art ion beamprocessing techniques for figure error correction and planarization, either by direct aluminum machining or with the aid of polymer or inorganic, amorphous surface films.

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“…For earth-observation satellites, many optical systems such as spectrometers are based on reflective optics (mirrors) that can be realized by, e.g. ultra-precise manufacturing of aluminum based materials in combination with a polishable layer of amorphous nickel-phosphorus alloy (NiP) [1][2][3][4][5][6][7]. For an athermal system behavior, the necessary housing structure is realized out of the same material.…”

Section: Introductionmentioning

confidence: 99%

Stray light reduction of silicon particle reinforced aluminum for optical systems

Kinast

Telle

Schröder

et al. 2019

International Conference on Space Optics — ICSO 2018

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Silicon particle reinforced aluminum containing 42 wt.% silicon (Al-42Si) offers higher specific stiffness, higher resistance to thermal gradients, and an athermal behavior combined with electroless nickel, in comparison to state-of-theart aluminum alloys (e.g. Al6061). Nevertheless, typical surface modifications (e.g. black anodization) lead to a nonsufficient optical stray light suppression due to the high amount of silicon particles on the surface. Therefore, a coating technique is required that fulfils the optical and the mechanical (e.g. adhesive strength) specifications for stray light reduction on Al-42Si. Different components like housings and barrels made of Al-42Si were coated with amorphous NiP and with Fractal Black™ by Acktar Ltd. The optical performance is analyzed by angle-resolved light scattering (ARS) at two different wavelengths (532 nm and 1064 nm). Fractal Black™ offers a total scattering level of lower than 2 % at 532 nm and 1064 nm. Fractal Black™ has been proven as a suitable coating for components made of Al-42Si.

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Large stable aluminum optics for aerospace applications

Cited by 33 publications

References 0 publications

Ion beam planarization of optical aluminum surfaces

Ion beam planarization of optical aluminum surfaces

Finishing of metal optics by ion beam technologies

Stray light reduction of silicon particle reinforced aluminum for optical systems

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