Removal character of vertical jet polishing with eccentric rotation motion using magnetorheological fluid

Wang, Tan; Cheng, Haobo; Dong, Zhichao; Tam, Hwa Yaw

doi:10.1016/j.jmatprotec.2013.03.017

Cited by 43 publications

(21 citation statements)

References 8 publications

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“…Sub-aperture polishing processes are characterized by a small tool whose dwell time map on the optic is implemented by computer control, thus they are also known as computer controlled optical surfacing (CCOS). Various CCOS processes have been developed since the 1970s, such as small tool computer controlled polishing [7,8], Magnetorheological Finishing [9], ion beam finishing [10], and so forth [11,12]. These processes have brought great promotion of surface figure.…”

Section: Introductionmentioning

confidence: 99%

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

Liao¹,

Zhang²,

Xie³

et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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Full-aperture polishing is a significant process in fabricating large optical flats because it restrains Mid-Spatial Frequency errors and removes material quickly on the whole optic surface. Nevertheless, optical flats fabricated by full-aperture polishing generally fail to meet the stringent requirement of surface figure, which has to be corrected by sub-aperture polishing processes. Surface figure of optical flats in full-aperture polishing processes is primarily dependent on the pressure distribution uniformity which correlates intensively with the lap shape. At present, practical and precise means are urgently desired for measuring and correcting the lap shape, especially the polyurethane pad lap. In the study, we present a novel method for deterministic measurement of the pad shape. The method obtains the height of the pad at spirally distributed locations implemented by the revolution of the pad and translation of the laser displacement sensor. The pad shape in terms of matrixes whose elements representing the heights at the corresponding locations is then calculated by interpolation algorithm based on the obtained data. Further, we propose a method for deterministic correction of the pad shape utilizing a small conditioning tool. The dwell time algorithm and implementation strategy for the dwell time are provided for common full-aperture polishers. These solutions for the deterministic measurement and correction of the pad shape have been validated on a full-aperture polisher with polyurethane pad. The polishing experiments revealed that the optic surface figure was obviously improved.

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Section: Introductionmentioning

confidence: 99%

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

Liao¹,

Zhang²,

Xie³

et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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“…[1][2][3][4]. Generally, a deterministic subaperture CCOS process relies on three key elements: (1) the exact surface form measured by a laser interferometer or other profilers; (2) the stable and quantitative tool influence function (TIF) with proper size and removal rate produced by polishing tools, such as rigid tools [5,6], pitch tools [7,8], conformal tools [9] and other semi-compliant or compliant tools [10][11][12][13][14][15][16][17][18];…”

Section: Introductionmentioning

confidence: 99%

“…Another alternative method to be more quick and economical may be numerical simulations of TIFs according to the classical Preston [6,7,13,[15][16][17][18] or other modified models [22]. These models lead us to believe that the material removal at the contact interface is mostly produced by interactions of the polishing pad, abrasives, and the workpiece; then the TIF can be simulated by relative velocity, pressure distribution, and other parameters at the working interface.…”

Section: Introductionmentioning

confidence: 99%

Modified subaperture tool influence functions of a flat-pitch polisher with reverse-calculated material removal rate

Dong¹,

Cheng²,

Tam³

2014

Appl. Opt.

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Numerical simulation of subaperture tool influence functions (TIF) is widely known as a critical procedure in computer-controlled optical surfacing. However, it may lack practicability in engineering because the emulation TIF (e-TIF) has some discrepancy with the practical TIF (p-TIF), and the removal rate could not be predicted by simulations. Prior to the polishing of a formal workpiece, opticians have to conduct TIF spot experiments on another sample to confirm the p-TIF with a quantitative removal rate, which is difficult and time-consuming for sequential polishing runs with different tools. This work is dedicated to applying these e-TIFs into practical engineering by making improvements from two aspects: (1) modifies the pressure distribution model of a flat-pitch polisher by finite element analysis and least square fitting methods to make the removal shape of e-TIFs closer to p-TIFs (less than 5% relative deviation validated by experiments); (2) predicts the removal rate of e-TIFs by reverse calculating the material removal volume of a pre-polishing run to the formal workpiece (relative deviations of peak and volume removal rate were validated to be less than 5%). This can omit TIF spot experiments for the particular flat-pitch tool employed and promote the direct usage of e-TIFs in the optimization of a dwell time map, which can largely save on cost and increase fabrication efficiency.

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“…To that aim, various processes of subaperture polishing [computer-controlled polishing (CCP)] are developed for high-precision components in optical manufacture at present, for instance, computer control optical surfacing (CCOS) [1][2][3], bonnet polishing (BP) [4,5], fluid jet polishing (FJP) [6][7][8], and magnetorheological jet polishing (MJP) [9][10][11]. Generally, they can be divided into two process classes, which are distinguished by the generation mechanism of the footprint [8].…”

Section: Introductionmentioning

confidence: 99%

“…The other class is the kinetic machining methods, where the footprint is generated by process parameters and not by tool contact, e.g., ion beam polishing (IBF) [12], FJP, and MJP. Therefore, the surface form and located position are the weaker effects for uniform removal character [8,10]. The MJP, which was initially developed by QED [13], is characterized by steady and small footprints.…”

Section: Introductionmentioning

confidence: 99%

Strategy of restraining ripple error on surface for optical fabrication

et al. 2014

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The influence from the ripple error to the high imaging quality is effectively reduced by restraining the ripple height. A method based on the process parameters and the surface error distribution is designed to suppress the ripple height in this paper. The generating mechanism of the ripple error is analyzed by polishing theory with uniform removal character. The relation between the processing parameters (removal functions, pitch of path, and dwell time) and the ripple error is discussed through simulations. With these, the strategy for diminishing the error is presented. A final process is designed and demonstrated on K9 work-pieces using the optimizing strategy with magnetorheological jet polishing. The form error on the surface is decreased from 0.216λ PV (λ=632.8 nm) and 0.039λ RMS to 0.03λ PV and 0.004λ RMS. And the ripple error is restrained well at the same time, because the ripple height is less than 6 nm on the final surface. Results indicate that these strategies are suitable for high-precision optical manufacturing.

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Removal character of vertical jet polishing with eccentric rotation motion using magnetorheological fluid

Cited by 43 publications

References 8 publications

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

Modified subaperture tool influence functions of a flat-pitch polisher with reverse-calculated material removal rate

Strategy of restraining ripple error on surface for optical fabrication

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