Creation of perfect surfaces

Mori, Yojiro; Yamamura, Kazuya; Endo, Kazuhiko; Yamauchi, Kazuto; Yasutake, Kiyoshi; Goto, Hidekazu; Kakiuchi, Hiroaki; Sano, Yasuhisa; Mimura, Hidekazu

doi:10.1016/j.jcrysgro.2004.10.097

Cited by 46 publications

(34 citation statements)

References 36 publications

(25 reference statements)

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“…It utilizes the chemical reaction between the neutral radicals and the surface atoms to achieve precision surface without any geometric and crystallographic damage. 17, 58 Highly reactive neutral radicals are generated under the influence of atmospheric pressure radio frequency (RF) plasma by decomposing the supplied reactive gas (composition: He, SF6 or CF4 and O2) in the working gap (gap between the electrode and workpiece surface). 59 The material is removed as volatile molecules owing to the reaction between generated radicals and surface atoms as shown in Figure 9.…”

Section: Precision Finishing Techniques Used For Fabrication Of Opticmentioning

confidence: 99%

“…Plasma etching process is also working on the same principle, but it has low material removal ability as it works under very low pressure (1–10– 3 Torr). 17 In case of PCVM (working pressure ≥ 1 atm), machining efficiency is higher owing to the high radical density and small mean free path of ions which leads to low kinetic energy. 60 Surface roughness in atomic order without any surface or subsurface damage may be accomplished owing to the isotropic etching.…”

Section: Precision Finishing Techniques Used For Fabrication Of Opticmentioning

confidence: 99%

“…Surface or subsurface defects such as dislocations and micro cracks cannot be avoided as the material is removed through the plastic deformation or brittle fracture. 16, 17 Figure 2 shows the classification of the precision finishing techniques based on their working principle. In mechanical precision finishing processes, the abrasive particles interact with the work surface either as a rigid tool or a tool with flexible backing, or with a fluid medium.…”

Section: Introductionmentioning

confidence: 99%

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Review of several precision finishing processes for optics manufacturing

Ghosh

Sidpara

Bandyopadhyay

2018

Journal of Micromanufacturing

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The ultrasmooth optical components with atomic-order surface roughness and nanometre-level shape accuracy are in immense demand with the rapid advancement of modern optical technology. In recent years, aspherical and free-form surfaces are gaining more interest for its favorable properties. Moreover, the new optical materials with immensely enhanced mechanical properties are being developed to meet the stringent requirements of modern optics. Fabrication of complex-shaped ultrasmooth optical components becomes a significant challenge as conventional finishing techniques are unable to machine aspherical or free-form surfaces precisely. This situation demands some highly deterministic finishing processes. Mostly, the optical components are fabricated by shaping or pre-finishing methods followed by final finishing processes. In the shaping or pre-finishing methods, the rigid abrasive tools are used to remove the material at an enhanced rate and near net shape of the elements can be attained. Surface finish and shape accuracy can also be improved to some extent. Owing to the presence of residual finishing marks generated by shaping methods, the application of the components is limited to the infrared (IR) optics. Final finishing processes include more deterministic and flexible polishing techniques that can achieve desired surface finish, figure accuracy and surface integrity to make it suitable for shorter wavelength applications. In recent years, single point diamond turning, precision grinding, plasma chemical vaporization machining and magnetorheological fluid-based finishing are widely used for fabricating ultrasmooth optics. In this article, principle, mechanism of material removal and applicability of the aforementioned precision finishing processes to different materials are discussed.

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Section: Precision Finishing Techniques Used For Fabrication Of Opticmentioning

confidence: 99%

Section: Precision Finishing Techniques Used For Fabrication Of Opticmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Review of several precision finishing processes for optics manufacturing

Ghosh

Sidpara

Bandyopadhyay

2018

Journal of Micromanufacturing

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“…When the vacuum pressure is released, the bottom surface of the workpiece will be shaped into an aspheric shape and the top surface will restore to its flat surface form by internal force and bending moments. Consequently, for machining materials which have excellent physical properties due to their perfect crystal structures, the elastic deformation method is appropriate [19].…”

Section: Introductionmentioning

confidence: 99%

FEA and Experimentally Determination of Applied Elasticity Problem for Fabricating Aspheric Surfaces

Nguyen¹

2019

Elasticity of Materials - Basic Principles and Design of Structures

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The elastic deformation machining method is suitable for fabricating aspheric surfaces that have excellent physical properties of elastic materials. The machining process is carried out with the deformation model without mold. When vacuum pressure is supplied to the workpiece, the top surfaces of workpiece are deformed into aspheric shape. After machining process, the bottom surface will be formed into the aspheric shape and the top surface returns to its original flat surface form due to internal force and bending moments of the material. However, the accuracy will decrease due to the reduced thickness while the vacuum pressure keeps unchanged during machining process. Therefore, it is necessary to carry out the finite element analysis (FEA) to determine the vacuum pressure with corresponding to the reduced thickness. In addition, the mold with its surface approximates and the desired surface form of the lens is also presented. When uniform vacuum pressure is supplied to the workpiece through small holes of the mold, the workpiece will be deformed into aspheric profile as similar to the mold surfaces. In order to improving the form accuracy, the FEA and the experiment are studied for modifying the mold profile to correspond with bending strength of workpiece material.

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“…The Osaka University in Japan has developed the plasma chemical vaporization machining (PCVM) method. PCVM utilizes various types of rotary electrodes to generate reactive plasma [5,6]. Researchers at Harbin Institute of Technology in China have developed the atmospheric pressure plasma polishing (APPP) method [7,8].…”

Section: Introductionmentioning

confidence: 99%

Application of atmospheric pressure plasma polishing method in machining of silicon ultra-smooth surfaces

Zhang

Wang

Dong

2008

Front. Electr. Electron. Eng. China

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The modern optics industry demands rigorous surface quality with minimum defects, which presents challenges to optics machining technologies. There are always certain defects on the final surfaces of the components formed in conventional contacting machining processes, such as micro-cracks, lattice disturbances, etc. It is especially serious for hard-brittle functional materials, such as crystals, glass and ceramics because of their special characteristics. To solve these problems, the atmospheric pressure plasma polishing (APPP) method is developed. It utilizes chemical reactions between reactive plasma and surface atoms to perform atom-scale material removal. Since the machining process is chemical in nature, APPP avoids the surface/subsurface defects mentioned above. As the key component, a capacitance coupled radio-frequency plasma torch is first introduced. In initial operations, silicon wafers were machined as samples. Before applying operations, both the temperature distribution on the work-piece surface and the spatial gas diffusion in the machining process were studied qualitatively by finite element analysis. Then the following temperature measurement experiments demonstrate the formation of the temperature gradient on the wafer surface predicted by the theoretical analysis and indicated a peak temperature about 90uC in the center. By using commercialized form talysurf, the machined surface was detected and the result shows regular removal profile that corresponds well to the flow field model. Moreover, the removal profile also indicates a 32 mm 3 /min removal rate. By using atomic force microscopy (AFM), the surface roughness was also measured and the result demonstrates an Ra 0.6 nm surface roughness. Then the element composition of the machined surface was detected and analyzed by Xray photoelectron spectroscopy (XPS) technology. The results also demonstrate the occurrence of the anticipated main reactions. All the experiments have proved that this atmospheric pressure plasma polishing method has the potential to achieve the manufacture of high quality optical surfaces.

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Creation of perfect surfaces

Cited by 46 publications

References 36 publications

Review of several precision finishing processes for optics manufacturing

Review of several precision finishing processes for optics manufacturing

FEA and Experimentally Determination of Applied Elasticity Problem for Fabricating Aspheric Surfaces

Application of atmospheric pressure plasma polishing method in machining of silicon ultra-smooth surfaces

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