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Li Y.,Fine Optical Engineering Research Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

The progress in the polishing of glass, in particular fused silica glass, with bound-abrasive is reviewed in the paper. The technique is rather successful in some respects, e.g. material removal rate, surface roughness, flatness of substrates. The surface roughness can be as low as <0.5nm (Ra) comparable with loose pad/pitch polishing for fused silica. On the other hand, the material removal rate is so high that the ground surface can be polished to specular (Ra:1∼2nm) within a quarter of an hour. The technique can be adapted to polish plane, spherical, aspheric surfaces and even free-form surface. The technique is next to free of subsurface damage after slightly wet chemical etching. Because ceria is utilized as abrasives and epoxy resin as binding materials softer than or comparable to fused silica, the shape of the polishing tools is easy to be shaped and dressed and need no truing. The technique may provide a potential solution to fast polishing of glass. © 2015 SPIE.

Fu Y.,Xihua University | Li Y.,Fine Optical Engineering Research Center
Journal of Optoelectronics and Advanced Materials | Year: 2014

Fixed-abrasive polishing of fused silica glass in conjunction with vibration under dry conditions was developed. Preliminary results show that material removal rate can be raised by up to >50% by applying vibration in fixed-abrasive polishing of fused silica. The likely reasons are reckoned to be outstanding capability of dispelling debris populated at the interface between polishing tool and glass, which is considered to hinder polishing process. On the other hand, surface roughness of polished fused silica is slightly degraded in vibration polishing compared to that without vibration. Certain periodical structure resulting from vibration appears on the machined surface, of which the spatial period is consistent with vibration. The mechanism of material removal in dry polishing is due probably to the synergy of chemical and mechanical effects between ceria and silica in polishing tool and workpiece, respectively. Ceria in the tool first bonds with silica to form Ce-O-Si systems under extreme pressure and then the Si-O de-bonds owing to the greater strength of the Ce-O; this way, debris forms and glass is polished.

Wang C.,Xiamen University | Wang C.,China Academy of Engineering Physics | Yang W.,Xiamen University | Wang Z.,Xiamen University | And 5 more authors.
Applied Optics | Year: 2014

The calculation of the dwell time plays a crucial role in polishing precision large optics. Although some studies have taken place, it remains a challenge to develop a calculation algorithm which is absolutely stable, together with a high convergence ratio and fast solution speed even for extremely large mirrors. For this aim, we introduced a self-adaptive iterative algorithm to calculate the dwell time in this paper. Simulations were conducted in bonnet polishing (BP) to test the performance of this method on a real 430 mm × 430 mm fused silica part with the initial surface error PV = 1741.29 nm, RMS = 433.204 nm. The final surface residual error in the clear aperture after two simulation steps turned out to be PV = 11.7 nm, RMS = 0.5 nm. The results confirm that this method is stable and has a high convergence ratio and fast solution speed even with an ordinary computer. It is notable that the solution time is usually just a few seconds even on a 1000 mm × 1000 mm part. Hence, we believe that this method is perfectly suitable for polishing large optics. And not only can it be applied to BP, but it can also be applied to other subaperture deterministic polishing processes. © 2014 Optical Society of America.

Wang J.,Fine Optical Engineering Research Center | Li Y.,Fine Optical Engineering Research Center | Li Y.,Akita Prefectural University | Han J.,University of Sichuan | And 2 more authors.
Journal of the European Optical Society | Year: 2011

Hard brittle materials (e.g. glasses and ceramics) increasingly appeal to general interests because of their excellent physical, mechanical and chemical properties such as infer hardness and strength at extreme temperature and chemical stability. The precision manufacturing of these materials is primarily achieved by grinding and polishing, which generally employs abrasives to wear the materials. With this manufacturing technology, the materials are removed due principally to the fracture of brittle materials, which will leave a cracked layer on the surface of manufactured components, namely subsurface damage (SSD). The subsurface damage affects the strength, performance and lifetime of components. As a result, investigation into the subsurface damage is needed. A host of characterizing techniques have been developed during the past several decades. These techniques based on different mechanisms provide researchers with invaluable information on the subsurface damage in various materials. In this article the typical SSD evaluation techniques are reviewed, which are regularly used in optical workshops or laboratories.

Li Y.,Fine Optical Engineering Research Center | Li Y.,Akita Prefectural University | Wu Y.,Akita Prefectural University | Wang J.,Fine Optical Engineering Research Center | And 3 more authors.
Optics Express | Year: 2012

Ultrasonic vibration has been employed to improve the quality of machined surface in the grinding of brittle materials. In this report, we transplant the philosophy of ultrasonic vibration assisted grinding to chemo-mechanical bound-abrasive-pellet polishing in anticipation of the improvement in either surface roughness or material removal rate. The preliminary experimental results show that the ultrasonic vibration assisted chemo-mechanical pellet polishing can yield desired results that material removal rate can be significantly raised while surface roughness is not degraded. The experimental results also indicate different mechanisms between ultrasonic-vibration-assisted chemo-mechanical pellet polishing and conventional chemo-mechanical bound-abrasive polishing. © 2011 Optical Society of America.

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