Dwell-time algorithm for polishing large optics

Wang, Chunjin; Yang, Wei; Wang, Zhenzhong; Xu, Yang; Hu, Chenlin; Zhong, Bo; Guo, Yinbiao; Xu, Qiao

doi:10.1364/ao.53.004752

Cited by 61 publications

(26 citation statements)

References 26 publications

(47 reference statements)

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“…Although practical fluid jet polishing is hardly affected by the polishing edge effect [21], the edge-up phenomenon occurs when performing polishing removal simulations, which is a common problem that is difficult to avoid when solving the dwell time [22,23]. In this algorithm, to avoid the influence of this phenomenon on the solution in the region of interest, the polished surface and its form error will extend outward by a specified distance, and so does the planned polishing path, as shown in Figure 7b.…”

Section: Variable Pitch Spiral Path Planning Methodsmentioning

confidence: 99%

Theoretical Study of Path Adaptability Based on Surface Form Error Distribution in Fluid Jet Polishing

et al. 2018

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In the technology of computer-controlled optical surfacing (CCOS), the convergence of surface form error has a close relationship with the distribution of surface form error, the calculation of dwell time, tool influence function (TIF) and path planning. The distribution of surface form error directly reflects the difference in bulk material removal depth across a to-be-polished surface in subsequent corrective polishing. In this paper, the effect of path spacing and bulk material removal depth on the residual error have been deeply investigated based on basic simulation experiments excluding the interference factors in the actual polishing process. With the relationship among the critical evaluation parameters of the residual error (root-mean-square (RMS) and peak-to-valley (PV)), the path spacing and bulk material removal depth are mathematically characterized by the proposed RMS and PV maps, respectively. Moreover, a variable pitch path self-planning strategy based on the distribution of surface form error is proposed to optimize the residual error distribution. In the proposed strategy, the influence of different bulk material removal depths caused by the distribution of surface form error on residual error is compensated by fine adjustment of the path spacing according to the obtained path spacing optimization models. The simulated experimental results demonstrate that the residual error optimization strategy proposed in this paper can significantly optimize the overall residual error distribution without compromising the convergence speed. The optimized residual error distribution obtained in sub-regions of the polished surface is more uniform than that without optimization and is almost unaffected by the distribution of parent surface form error.

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Section: Variable Pitch Spiral Path Planning Methodsmentioning

confidence: 99%

Theoretical Study of Path Adaptability Based on Surface Form Error Distribution in Fluid Jet Polishing

et al. 2018

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“…The polishing time at each dwell point (i.e. the dwell map) can be solved with various algorithms such as discrete convolution model, the linear equation model and so forth [17]. Finally, the CNC code can be generated according to the dwell point on the path and the dwell time map.…”

Section: Development Of the Multi-pitch Tool Pathmentioning

confidence: 99%

Development of multi-pitch tool path in computer-controlled optical surfacing processes

Hou

Liao

Wang

2017

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

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Background: Tool path in computer-controlled optical surfacing (CCOS) processes has a great effect on middle spatial frequency error in terms of residual ripples. Raster tool path of uniform path pitch is one of the mostly adopted paths, in which smaller path pitch is always desired for restraining residual ripple errors. However, too dense paths cause excessive material removal in lower removal regions deteriorating the form convergence. Methods: With this in view, we propose a novel tool path planning method named multi-pitch path. With the path, the material removal map is divided into several regions with varied path pitches according to the desired removal depth in each region. The path pitch is designed larger at low removal regions while smaller at high removal regions, and the feeding velocity of the tool is maintained at high level when scanning the whole surface. Results and conclusions:Experiments were conducted to demonstrate this novel tool path planning method, and the results indicate that it can successfully restrain the residual ripples, and meanwhile guarantee favorable convergent rate of form error.

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“…Spiral tool path is adopted, and the dwell points are generated according to Eq. (7) [29]. Afterwards the pad shape correction process is conducted and the resultant pad shape is shown in Figure 14.…”

Section: Correction Of the Pad Shape And Polishing Experimentsmentioning

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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Dwell-time algorithm for polishing large optics

Cited by 61 publications

References 26 publications

Theoretical Study of Path Adaptability Based on Surface Form Error Distribution in Fluid Jet Polishing

Theoretical Study of Path Adaptability Based on Surface Form Error Distribution in Fluid Jet Polishing

Development of multi-pitch tool path in computer-controlled optical surfacing processes

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

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