Efficient polishing of aspheric optics

Taylor, John S.; Piscotty, M. A.; Nguyen, Nhan; Landram, C.S.; Ng, L.C.

doi:10.2172/591787

Cited by 3 publications

(2 citation statements)

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“…Smoothing experiments using different polishing processes to control the RMS surface roughness value have previously been reported [4][5][6][7][8][9][10][11][12][13][14]. Most have focused on measurements within an area of ≤1 mm 2 , and have only compared RMS surface roughness values (the collapsed or integrated information of the fundamental PSD functions) for different methods.…”

Section: Introductionmentioning

confidence: 99%

Experimental power spectral density analysis for mid- to high-spatial frequency surface error control

et al. 2017

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The control of surface errors as a function of spatial frequency is critical during the fabrication of modern optical systems. A large-scale surface figure error is controlled by a guided removal process, such as computer-controlled optical surfacing. Smaller-scale surface errors are controlled by polishing process parameters. Surface errors of only a few millimeters may degrade the performance of an optical system, causing background noise from scattered light and reducing imaging contrast for large optical systems. Conventionally, the microsurface roughness is often given by the root mean square at a high spatial frequency range, with errors within a 0.5×0.5 mm local surface map with 500×500 pixels. This surface specification is not adequate to fully describe the characteristics for advanced optical systems. The process for controlling and minimizing mid- to high-spatial frequency surface errors with periods of up to ∼2-3 mm was investigated for many optical fabrication conditions using the measured surface power spectral density (PSD) of a finished Zerodur optical surface. Then, the surface PSD was systematically related to various fabrication process parameters, such as the grinding methods, polishing interface materials, and polishing compounds. The retraceable experimental polishing conditions and processes used to produce an optimal optical surface PSD are presented.

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Section: Introductionmentioning

confidence: 99%

Experimental power spectral density analysis for mid- to high-spatial frequency surface error control

et al. 2017

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“…Elastic emission technology EEM 4 uses rapidly spinning polyurethane ball moving above optics -leaving again gap of few micrometers thick between tool and optic surface filled by standard polishing slurry. Several other groups developed different version of hydrodynamic polishing tools 5,6,7,8 . All these technologies indicate that lateral flow of polishing slurry at high speed over the lens surface not only improves surface roughness but also removes subsurface damage.…”

Section: Introductionmentioning

confidence: 99%

Super-polishing of Zerodur aspheres by means of conventional polishing technology

et al. 2015

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This paper describes a quest to find simple technique to superpolish Zerodur asphere (55µm departure from best fit sphere) that could be employed on old fashion way 1-excenter optical polishing machine. The work focuses on selection of polishing technology, study of different polishing slurries and optimization of polishing setup. It is demonstrated that either by use of fine colloidal CeO 2 slurry or by use of bowl-feed polishing setup with CeO 2 charged pitch we could reach 0.4nm RMS roughness while removing <30nm of surface layer. This technique, although not optimized, was successfully used to improve surface roughness on already prepolished Zerodur aspheres without necessity to involve sophisticated super-polishing technology and highly trained manpower.

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A Low Contact Force Polishing System for Micro Molds that Utilizes 2-Dimensional Low Frequency Vibrations (2DLFV) with Piezoelectric Actuators (PZT) and a Mechanical Transformer Mechanism

Chee¹,

Suzuki²,

Uehara³

et al. 2013

Int. J. Automation Technol.

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This study proposes and develops a novel polishing system for micro molds which need high precision polishing, high aspect ratio of micro channel structure, or further miniaturization for micro channel structure. The proposed system has been named a “low contact force polishing system for micro mold utilizing 2-dimensional low frequency vibrations (2DLFV) with piezoelectric actuators (PZTs) and a mechanical transformer mechanism.” The system consists of 2DLFV with PZTs incorporated into the mechanical transformer structure, a low contact force loader, and a polishing tool. The shape of the polishing tool is flexible and can be changed depending on the complicatedness of the shape of the work. Several experiments are conducted to evaluate the performance of the polishing system. The evaluation reveals that a convex removal footprint can be easily achieved with the polishing system. The fact that the relationship between the removal depth and the polishing time suit Preston’s law well shows a stable polishing process is realized with the system. The polishing performances remains the same even if the shape of the polishing tool is changed. This indicates that the system can use polishing tools of a wide selection of shapes, which allows the system to polish a large variety of materials and most of the complicated shapes of metal structures, achieving a dramatic reduction in surface roughness. The plano raster polishing results also show the system to be well suited to the dwell time control polishing because the results show the removal footprint to be proportional to the dwell time and the defined raster path. All in all, the system is a versatile polishing system capable of achieving the intended objectives.

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Efficient polishing of aspheric optics

Cited by 3 publications

References 0 publications

Experimental power spectral density analysis for mid- to high-spatial frequency surface error control

Experimental power spectral density analysis for mid- to high-spatial frequency surface error control

Super-polishing of Zerodur aspheres by means of conventional polishing technology

A Low Contact Force Polishing System for Micro Molds that Utilizes 2-Dimensional Low Frequency Vibrations (2DLFV) with Piezoelectric Actuators (PZT) and a Mechanical Transformer Mechanism

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