Details of a Researcher - Beaucamp, Anthony

Papers - Beaucamp, Anthony

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Advances in corrective finishing of optical moulds for future aspheric hard X-ray telescopes

Beaucamp, A. and Namba, Y. and Charlton, P. and Freeman, R.

Optics InfoBase Conference Papers 2013

Advances in Corrective Finishing of Optical Moulds for Future Aspheric Hard X-ray Telescopes

Anthony T. Beaucamp and Yoshiharu Namba and Phillip Charlton and Richard R. Freeman

Frontiers in Optics 2013 ($\lbrace$OSA$\rbrace$) 2013

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Advances in corrective finishing of optical moulds for future aspheric hard X-ray telescopes

Beaucamp A., Namba Y., Charlton P., Freeman R.

Optics InfoBase Conference Papers 2013

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Advances in corrective finishing of optical moulds for future aspheric hard X-ray telescopes

Anthony Beaucamp, Yoshiharu Namba, Phillip Charlton, Richard Freeman

Optics InfoBase Conference Papers FTh4 ( E1 ) 2013

Accepted

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Automated finishing of diamond turned dies for hard X-ray and EUV optics replication

Beaucamp A., Namba Y., Freeman R.

Proceedings of SPIE - The International Society for Optical Engineering 8502 2012.12

ISSN 0277786X

Ultra-precision diamond turning can deliver very accurate form, often less than 100nm P-V. A possible manufacturing method for thin Wolter type-1 mirrors in hard X-ray space telescopes thus involves generating electroless nickel plated mandrels by diamond turning, before coating them with a reflective film and substrate. However, the surface texture after turning falls far short from the requirements of X-ray and EUV applications. The machining marks need to be removed, with hand polishing still widely employed. There is thus a compelling need for automated finishing of turned dies. A two step finishing method is presented that combines fluid jet and precessed bonnet polishing on a common 7- axis CNC platform. This method is capable of finishing diamond turned electroless nickel plated dies down to 0.28nm rms roughness, while deterministically improving form error down to 30nm P-V. The fluid jet polishing process, which consists of pressurizing water and abrasive particles for delivery through a nozzle, has been specially optimized with a newly designed slurry delivery unit and computer simulations, to remove diamond turning marks without introducing another waviness signature. The precessed bonnet polishing method, which consists of an inflated membrane rotated at an angle from the local normal to the surface and controlled by geometrical position relative to the work-piece, is subsequently employed with a novel control algorithm to deliver scratch-free surface roughness down to 0.28 nm rms. The combination of these two deterministic processes to finish aspheric and freeform dies promises to unlock new frontiers in X-ray and EUV optics fabrication. © 2012 SPIE.

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Finishing of electroless nickel plated dies for hard X-ray mirror replication

Anthony T. Beaucamp, Akihiro Matsumoto, Yoshiharu Namba

Proceedings - ASPE 2012 Annual Meeting ( 54 ) 414 - 417 2012.12

Accepted

Edge-control and surface-smoothness in sub-aperture polishing of mirror segments

D. Walker, A. Beaucamp, R. Evans, T. Fox-Leonard, N. Fairhurst, C. Gray, S. Hamidi, H. Li, W. Messalink, J. Mitchell, P. Rees, G. Yu

Proceedings of SPIE - The International Society for Optical Engineering 8450 2012.12

Accepted, ISSN 0277786X

This paper addresses two challenges in establishing a new process chain for polishing hexagonal segments for extremely large telescopes:- i) control of edge and corner profiles in small-tool polishing of hexagons, and ii) achieving the required smoothness of the bulk aspheric form. We briefly describe the performance of a CNC-grinding process used to create the off-axis asphere, which established the input-quality for subsequent processing. We then summarize processes for smoothing ground mid-spatials and pre- and corrective polishing using Zeeko CNC machines. The impact of two cases is considered; i) all processing stages are performed after the segment is cut hexagonal, and ii) final rectification of a hexagon after cutting from an aspherised roundel, as an alternative to ionfiguring. We then report on experimental results on witness samples demonstrating edges and corners close to the EELT segment specification, and results on a full-aperture spherical segment showing excellent surface smoothness. © 2012 SPIE.

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Edges in CNC polishing: From mirror-segments towards semiconductors, paper 1: Edges on processing the global surface

David Walker, Guoyu Yu, Hongyu Li, Wilhelmus Messelink, Rob Evans, Anthony Beaucamp

Optics Express 20 ( 18 ) 19787 - 19798 2012.08

Accepted

Segment-edges for extremely large telescopes are critical for observations requiring high contrast and SNR, e.g. detecting exo-planets. In parallel, industrial requirements for edge-control are emerging in several applications. This paper reports on a new approach, where edges are controlled throughout polishing of the entire surface of a part, which has been pre-machined to its final external dimensions. The method deploys compliant bonnets delivering influence functions of variable diameter, complemented by small pitch tools sized to accommodate aspheric mis-fit. We describe results on witness hexagons in preparation for full size prototype segments for the European Extremely Large Telescope, and comment on wider applications of the technology. © 2012 Optical Society of America.

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Dynamic multiphase modeling and optimization of fluid jet polishing process

Anthony Beaucamp, Yoshiharu Namba, Richard Freeman

CIRP Annals - Manufacturing Technology 61 ( 1 ) 315 - 318 2012.04

Accepted, ISSN 00078506

Fluid jet polishing is a machining process used increasingly in the ultra-precision manufacture of optical components and replication molds. While the process bears some similarities with abrasive water jet machining, it operates at much lower pressure and grit size. This paper presents a computational fluid dynamics model based on latest multiphase turbulent flow computational methods, simulating dynamically the interface between fluid and air. The model is then used to optimize surface texture performance down to 1 nm Ra on electroless nickel plated optical dies, while removing diamond turning marks. Some conclusions are drawn regarding the nature of the removal mechanism. © 2012 CIRP.

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Fluid jet and bonnet polishing of optical moulds for application from visible to X-ray

Beaucamp A., Freeman R., Matsumoto A., Namba Y.

Proceedings of SPIE - The International Society for Optical Engineering 8126 2011.11

ISSN 0277786X

Electroless Nickel (ENi) and binderless Tungsten Carbide (WC) are materials widely used in industry to make replication moulds for precision optics, with applications ranging from consumer camera lenses to high accuracy X-ray mirrors. The aspheric shape generation is generally performed by diamond turning in the case of Nickel, and microgrinding in the case of Tungsten Carbide. However, both machining methods fall short from meeting the ultra-precision criteria required by an increasing number of applications, because of insufficient form accuracy and the frequency content of the machining marks they leave on the surface. It is thus commonly observed in industry that moulds need to be subsequently polished by hand, a usually slow and human resource intensive operation. The Zeeko 7-axis CNC machine, equipped with sub-aperture fluid jet and precessed bonnet polishing technology, has been used to develop deterministic finishing processes on both Electroless Nickel and Tungsten Carbide. Corrective polishing to less than λ/20 (<31nm PV) form error can be achieved, as well as the ability to smooth surface texture down to 1nm Ra or less, in a time efficient manner. © 2011 SPIE.

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Finishing of optical moulds to λ/20 by automated corrective polishing

A. Beaucamp, Y. Namba, I. Inasaki, H. Combrinck, R. Freeman

CIRP Annals - Manufacturing Technology 60 ( 1 ) 375 - 378 2011.06

Accepted, ISSN 00078506

Tungsten carbide is widely used to make replication moulds for small aspheric and freeform optics, like camera lenses. Since aspheric generation by grinding generally fails to reach ultra-precision criteria, a time efficient method for finishing moulds is needed. Using a 7-axis CNC polishing machine, an on-machine tool forming technique and compensation software were developed to correctively polish a plano WC surface of diameter 25 mm from a form error above λ to below λ/20 (29 nm P-V) in under 1 h, while reducing roughness to 1.0 nm Ra. This automatic method and tooling are applicable to aspheric and freeform moulds. © 2011 CIRP.

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Fluid jet and bonnet polishing of optical moulds for application from visible to X-ray

Beaucamp, A.T.H. and Freeman, R.R. and Matsumoto, A. and Namba, Y.

Proceedings of SPIE - The International Society for Optical Engineering 8126 2011

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Fluid jet and bonnet polishing of optical moulds for applications from visible to X-Ray

A. Beaucamp, R. Freeman, A. Matsumoto, Y. Namba

Proceedings of the 11th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2011 1 29 - 32 2011

Accepted, ISSN 0277-786X

Electroless Nickel (ENi) and binderless Tungsten Carbide (WC) are widely used to make replication moulds for optics ranging from consumer camera lenses to high-accuracy X-ray mirrors. Aspheric shape generation is generally performed by diamond turning in the case of Nickel, and micro-grinding in the case of Tungsten Carbide. Both machining methods fail in general to meet the ultra-precision criteria required by an increasing number of applications. A 7-axis CNC machine equipped with sub-aperture fluid jet and precessed bonnet polishing technology was used to develop deterministic finishing processes on both Electroless Nickel and Tungsten Carbide. Corrective polishing to less than λ/20 (<31nm PV) form error can be achieved, as well as the ability to smooth surface texture down to 1nm Ra or less.

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Ultra-precision fluid jet and bonnet polishing for next generation hard X-ray telescope application

Anthony Th Beaucamp, Akihiro Matsumoto, Yoshiharu Namba

Proceedings - ASPE 2010 Annual Meeting 50 57 - 60 2010.12

Accepted

A study of automation of hard X-Ray molding dies polishing by FJP and BP was carried out. The following conclusions were drawn: 1. Surface roughness in the range 0.6-0.8nm rms can be obtained on electroless nickel samples by a combination of Fluid Jet polishing with micro-particles followed by Bonnet polishing with nano-particles. 2. Automated corrective polishing was demonstrated on a borosilicate cylindrical sample, with form error improvement from PV 3.2um down to 0.18um. 3. By using the automated process to get surface texture down to circa 0.6-0.8nm rms, it is possible to reduce the time of final hand polishing to 0.3nm by as much as 75% [3].

Edge-control on mirror segments

Walker D.D., Beaucamp A., Yu G., Li H.

Optics InfoBase Conference Papers 2010

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Active control of edges and global microstructure on segmented mirrors

D. D. Walker, A. Beaucamp, C. Dunn, R. Evans, R. Freeman, R. Morton, S. Wei, G. Yu

Proceedings of SPIE - The International Society for Optical Engineering 7018 2008.11

Accepted, ISSN 0277786X

In this paper we address two interrelated issues important to primary mirror segments for extremely large telescopes - edge-control, and the detailed topography over the segment surface. Both affect the intensity and distribution of stray light and infrared emissivity. CNC polishing processes typically deploy spiral or raster tool-paths, tending to leave repetitive features. We compare and contrast two novel families of pseudo-random tool-paths for Precessions CNC polishing. We then show how CNC control of the three-dimensional tool-path can optimize edge-profiles. Finally, we demonstrate fluid-jet polishing used to clean up residual edge defects.

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Removal of diamond-turning signatures on x-ray mandrels and metal optics by fluid-jet polishing

A. Beaucamp, R. Freeman, R. Morton, Karthik Ponudurai, D. D. Walker

Proceedings of SPIE - The International Society for Optical Engineering 7018 2008.11

Accepted, ISSN 0277786X

This paper describes a major advance in the post-treatment of diamond-turned surfaces to remove repetitive micro-structure; a result which could have a major beneficial impact on fabrication of Walter-type X-ray mandrels, and metal mirrors. Diamond-turning is highly deterministic and versatile in producing axially-symmetric forms, and through fast-tool servos, non-axially symmetric, free-form and micro-structured surfaces. However, the fine turning marks left in the metal surface limit performance. In this paper, we describe how fluid-jet polishing under CNC control can be used to eliminate these structures, without significantly degrading the surface roughness or form produced by the prior turning operation.

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Ultra-precision polishing of electroless nickel molding dies for shorter wavelength applications

Y. Namba, T. Shimomura, A. Fushiki, A. Beaucamp, I. Inasaki, H. Kunieda, Y. Ogasaka, K. Yamashita

CIRP Annals - Manufacturing Technology 57 ( 1 ) 337 - 340 2008.05

Accepted, ISSN 00078506

Electroless nickel is one of the best materials for making optical molding dies, because of its machinability with both single-point diamond turning and polishing, as well as its suitable hardness and durability. This paper deals with the ultra-precision polishing of aspheric molding dies for next-generation hard X-ray telescope mirrors, which require a super smooth surface with a roughness below 0.3 nm root-mean-square (rms). The material was machined using various methods, and a surface roughness of 0.23 nm rms was obtained on aspheric molding dies of 300 mm in diameter. A surface roughness of 0.16 nm rms was achieved on platinum/carbon multilayer mirrors, replicated from plano dies. © 2008.

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Improving Surface PSD Using a Random Tool Path

Christina R. Dunn and David D. Walker and Anthony Beaucamp and John Kelchner and Richard Freeman

Frontiers in Optics 2008/Laser Science XXIV/Plasmonics and Metamaterials/Optical Fabrication and Testing ($\lbrace$OSA$\rbrace$) 2008

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Commissioning of the first Precessions 1.2m CNC polishing machines for large optics

D. D. Walker, A. T.H. Beaucamp, V. Doubrovski, C. Dunn, R. Evans, R. Freeman, G. McCavana, R. Morton, D. Riley, J. Simms, G. Yu, X. Wei

Proceedings of SPIE - The International Society for Optical Engineering 6288 2006.11

Accepted, ISSN 0277786X

This paper reports on the commissioning of the first of Zeeko's 'IRP1200' 1.2m capacity 7-axis automated CNC polishing machines. These combo machines now support five different removal regimes, which are described. The machines differ substantially from Zeeko's more familiar 200mm machines on which we have focused before, in terms of overall architecture and detailed design. Large and small optics place different demands on part-fixturing, tooling, machine speeds and accelerations, metrology, slurry-handling, part-loading and access etc. These have had a profound effect on the development-path from 200 to 1.2m machines. Moreover, an advance in the kinematic design has extended the allowable range of surface slope-angles from typically 30° up to a hemisphere. The paper presents results from the pass-off trials, the first fluid-jet experiment, and the development of tooling to address a requirement to smooth a part with a local defect.

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