Towards freeform curved blazed gratings using diamond machining

Bourgenot, Cyril; Robertson, David J.; Stelter, R. Deno; Eikenberry, S. S.

doi:10.1117/12.2231182

Cited by 11 publications

(14 citation statements)

References 13 publications

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“…They are increasingly used in pioneering optical designs offering abundant new opportunities for optical designers. 2 In particular, freeform surfaces help to improve compactness, image sharpness and contrast in a larger field of view. Freeform optics are therefore promising components for airborne or space-based hyperspectral imagers for their ability to reduce the overall dimension, and therefore mass, of the satellite's payload, which is a critical parameter in space imaging systems.…”

Section: The Astronomical Applications Of Freeform Opticsmentioning

confidence: 99%

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

Paenoi

Bourgenot²,

Atkins³

et al. 2022

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V

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Lightweight, aluminum, freeform prototype mirrors have been designed and fabricated by a Thai led team, with UK support, for intended applications within the Thai Space Consortium (TSC) satellite series. The project motivation was to explore the different design strategies and fabrication steps enabled by both conventional (mill, drill, and lathe) and additive (3D printing) manufacture of the prototype substrates. Single Point Diamond Turning was used to convert the substrates into mirrors and optical metrology was used to evaluate the different mirror surfaces.The prototype criteria originated from the TSC-1 satellite tertiary mirror, which is designed to minimize the effect of Seidel aberrations before the beam enters the hyperspectral imager. To converge upon the prototype designs, Finite Element Analysis (FEA) was used to evaluate the different physical conditions experienced by the prototypes during manufacture and how these influence the optical performance. The selected designs satisfied the mass and surface displacement criteria of the prototype and were adapted to either the conventional or additive manufacturing process. This paper will present the prototype design process, substrate manufacture, optical fabrication, and an interferometric evaluation of the optical surfaces comparing the conventional and additive manufacturing processes.

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Section: The Astronomical Applications Of Freeform Opticsmentioning

confidence: 99%

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

Paenoi

Bourgenot²,

Atkins³

et al. 2022

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V

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“…The design uses a custom freeform blazed grating made on a five-axis ultra-precision diamond machine to get the best optical performance while keeping the size and weight as small as possible. Bourgenot C et al [ 67 ] from Durham University in the UK wrote about the technical challenges and progress made in making convex blazed gratings on an ultra-precision five-axis Moore machine. They also talked about how the gratings are used as optical pupil reflectors in an integrated grating imaging spectrometer (IGIS) integral field unit prototype.…”

Section: Fabrication Capability Of Convex Blazed Gratingsmentioning

confidence: 99%

Progress in the Preparation and Characterization of Convex Blazed Gratings for Hyper-Spectral Imaging Spectrometer: A Review

Peng

Guan

et al. 2022

Micromachines

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Convex blazed gratings, which can effectively broaden the spectral range and improve spectral resolution, have gradually evolved into a crucial optical component for lightweight and compact imaging spectroscopy instruments. Their design, processing, and testing involve multidisciplinary interdisciplinary scientific issues, and they continue to be a major area of research in imaging optics applications. This paper summarizes the effects of various grating groove shapes and structural parameters on the spectral range and diffraction efficiency of convex blazed gratings, after providing a brief introduction to the typical functions and applications of convex blazed gratings. Firstly, the latest progress in typical processing methods for convex blazed gratings is reviewed. It focuses on the current fabrication processes and reviews their capabilities in creating convex blazed gratings from three main types of technologies, namely ultra-precision machining, high-energy density beam processing, and chemically assisted fabrication processes. Secondly, the adaptability of the manufacturing process for convex blazed gratings on different scales is summarized, analyzing the adaptation of current procedures to various grating fabrication scales and their bottlenecks. Finally, the characterization methods and future feasible characterization methods for convex blazed gratings are reviewed. The development trend of efficient and precise preparation of convex blazed gratings is pointed out.

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“…Graham C et al [ 16 ] designed an all-aluminum, rugged, lightweight, free-form grating-based near-infrared hyperspectral moisture sensing imager, FYMOS, which was machined on a five-axis ultra-precision diamond machine. Bourgenot C et al [ 17 ] from Durham University, UK, reported the technical challenges and progress in preparing such curved blazed gratings on an ultra-precision five-axis Moore machine, describing their application in an integrated grating imaging spectrometer (IGIS) integral field unit prototype, in which the free-form gratings were used as optical pupil reflectors. Bourgenot C et al [ 18 ] also discussed new opportunities for free-form gratings machined with diamond, and identified NiP as the substrate providing the best roughness and profile quality in a comparison of free-form gratings machined with RSA aluminum 6061 and RSA aluminum 443 surfaces chemically coated with NiP with an average roughness of 2.5 nm RMS per blazed surface.…”

Section: Introductionmentioning

confidence: 99%

Ultra-Precision Cutting and Characterization of Reflective Convex Spherical Blazed Grating Elements

Peng

Guan

et al. 2022

Micromachines

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In this work, based on the diffraction principle of reflective blazed grating, the structure size of the convex spherical blazed grating unit is determined, the machining accuracy of the convex spherical blazed grating is formulated, the effects of tool nose radius and Poisson burr on the diffraction efficiency of the convex spherical blazed grating are analyzed, and the performances of cutting convex gratings with microcrystalline aluminum RSA6061 and RSA6061+ chemically plated NiP for two workpiece materials are compared. A convex spherical blazed grating with a radius of curvature R = 41.104 mm, substrate diameter 14 mm, grating density 53.97 line/mm, and blaze angle of roughly 3.8° is turned by a four-axis ultra-precision machining system by adjustment of the cutting tool, workpiece material, and cutting parameters, as well as modification of the layouts of the blazed grating on the convex sphere. The results of the testing of convex spherical blazed grating elements in both layouts show that the size error of the grating period is close for both layouts, the size error of grating height is smaller in the equal-along-arc layout, the blaze angle error in the equal-along-projection layout is only 0.74%, and the average roughness of the blazed surface is less than 5 nm to meet the processing quality requirements of the reflective convex spherical blazed grating. The greater the blaze angle accuracy of the blazed grating, the higher its diffraction efficiency, so the grating element with an equal-along-projection layout has a higher diffraction efficiency than the grating element with an equal-along-arc layout. RSA6061+ chemically plated NiP material is superior to RSA6061 material in Poisson burr height and blazed surface roughness, which is more suitable for Offner-type imaging spectrometers in the spectral range 0.95–2.5 μm (SWIR).

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Towards freeform curved blazed gratings using diamond machining

Abstract: Towards freeform curved blazed gratings using diamond machining.', in Advances in optical and mechanical technologies for telescopes and instrumentation II. Bellingham, Washington: SPIE, p. 99123. Proceedings of SPIE. (9912).

Cited by 11 publications

References 13 publications

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

Progress in the Preparation and Characterization of Convex Blazed Gratings for Hyper-Spectral Imaging Spectrometer: A Review

Ultra-Precision Cutting and Characterization of Reflective Convex Spherical Blazed Grating Elements

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