Deterministic Manufacturing Processes for Precision Optical Surfaces

Pollicove, Harvey M.; Golini, Donald

doi:10.4028/www.scientific.net/kem.238-239.53

Cited by 31 publications

(18 citation statements)

References 0 publications

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“…Zeeko's Precessions TM using an inflated membrane polisher [4]) or they make direct contact with the workpiece (e.g. QED's MRF TM using a magneto-rheological fluid on a spinning wheel [5]). These polishing tools can conform to virtually any type of workpiece including aspheric and freeform surfaces.…”

Section: Comparison Between Rc Lap and Other Toolsmentioning

confidence: 99%

“…Various computer controlled optical surfacing (CCOS) processes have been developed since the 1960s [1][2][3][4][5][6]. CCOS processes can provide good solutions for fabrication of precision optics because of their high convergence rate based on deterministic removal processes.…”

Section: Introductionmentioning

confidence: 99%

“…CCOS processes can provide good solutions for fabrication of precision optics because of their high convergence rate based on deterministic removal processes. Many large aspheric optical surfaces and off-axis segments have been successfully fabricated using these techniques [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Rigid conformal polishing tool using non-linear visco-elastic effect

2010

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Computer controlled optical surfacing (CCOS) relies on a stable and predictable tool influence function (TIF), which is the shape of the wear function created by the machine. For a polishing lap, which is stroked on the surface, both the TIF stability and surface finish rely on the polishing interface maintaining intimate contact with the workpiece. Pitch tools serve this function for surfaces that are near spherical, where the curvature has small variation across the part. The rigidity of such tools provides natural smoothing of the surface, but limits the application for aspheric surfaces. Highly flexible tools, such as those created with an air bonnet or magnetorheological fluid, conform to the surface, but lack intrinsic stiffness, so they provide little natural smoothing. We present a rigid conformal polishing tool that uses a non-linear visco-elastic medium (i.e. non-Newtonian fluid) that conforms to the aspheric shape, yet maintains stability to provide natural smoothing. The analysis, design, and performance of such a polishing tool is presented, showing TIF stability of <10% and providing surface finish with <10A roughness.

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Section: Comparison Between Rc Lap and Other Toolsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rigid conformal polishing tool using non-linear visco-elastic effect

2010

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“…A mirror-finished surface can be achieved through different machining processes, such as chemical mechanical polishing [8], magnetorheological finishing [9], abrasive flow machining [10] and elastic emission machining [11]. In semiconductor manufacturing, chemical mechanical polishing or planarization has been the most widely used method of producing mirror-finished surfaces since the early 1990s.…”

Section: Introductionmentioning

confidence: 99%

Surface Topography Measurement of Mirror-Finished Surfaces Using Fringe-Patterned Illumination

Fang

Tjahjowidodo

2020

Metals

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Mirror-finished surface products have a wide range of applications in different engineering industries, such as power generation, aerospace, semiconductors and optics. The surface topography of mirror-finished products is typically measured in a metrology laboratory, which is typically time consuming and cannot be integrated into the manufacturing process. To allow for in-situ product quality assurance and automatic tool change for manufacturing processes, a more accurate and responsive surface-measurement method is needed. For highly polished surfaces, a sub-micron surface fluctuation makes it possible to use light-scattering effects and image processing for surface texture analysis. A non-contact surface inspection system using a fringe-patterned illumination method is proposed in this paper. A predesigned pattern was projected onto the target surface, and its reflected image was captured by a camera. It was found that the surface parameters Sa and Sq, which are widely used to evaluate surface quality, are significantly correlated with luminous-intensity distribution. Another parameter, Str, which quantifies the uniformity of surface-texture directions due to polishing or grinding marks, was traditionally quantified after a complete-surface topographic measurement. In this research, a new approach is proposed to determine surface isotropy through a luminance-intensity distribution analysis. By rotating the test coupon, the variation of specular reflection showed correlation with the significance of surface-texture direction. The experimental results demonstrate that mirror-finished surfaces with a large deviation in luminance intensity across the pattern possess low Str values, which indicates low uniformity in surface texture.

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“…By spending more time on high areas, a well-calibrated computer-controlled polishing tool can figure the optical surface in a predictable manner. Many large aspheric optical surfaces and off-axis segments have been successfully fabricated using these CCOS techniques [5][6][7][8]. However, these 'figuring' processes based on dwell time are fundamentally limited to the correction of low-spatialfrequency errors (i.e.…”

Section: Introductionmentioning

confidence: 99%