Field proven technologies for fabrication of high-precision aspheric and freeform optical surfaces

Nowadays, the surface quality of the material is crucial for industry and science. With the development of micro-electronics and optics, the demand for surface quality has become more and more rigorous, making optical surface polishing more and more critical. Plasma polishing technology is conceived as an essential tool for removing surface and subsurface damages from traditional polishing processes. The plasma processing technology is based on plasma chemical reactions and removes atomic-level materials. Plasma polishing can easily nano-finish hard-brittle materials such as ceramics, glass, crystal, fused silica, quartz, Safire, etc. The optical substrate with micro-level and nano-level surface roughness precision is in demand with the advancement in optics fabrication. The mechanical properties of super-finished optics materials are being used to fulfill the requirement of modern optics. This article discusses the processing of different types of freeform, complex and aspheric optical materials by the plasma polishing process used mainly by the optical industry. The plasma polishing devices developed in the last decade are thoroughly reviewed for their working principles, characteristics and applications. This article also examines the impact of various process parameters such as discharge power, rate of gas flow, mixed gas flow ratio and pressure on the plasma polishing process.

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“…Lormeau et al 87 Fused silica • A novel ultrafine MR fluid (C30) was employed to fabricate EUVL optics.…”

Section: Research Challenges For Optics Polishing By Plasmamentioning

confidence: 99%

Plasma polishing processes applied on optical materials: A review

Yadav

Kumar

et al. 2021

Journal of Micromanufacturing

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“…The surface roughness in the range of 1 Å–2 Å can be obtained throughout the fluid life and over a wide variety of machine types and wheel sizes. 94, 95 Recent advancements in MRF process make it suitable for improving low, mid- and high-spatial frequency errors to meet the ultra-high requirements of modern optics.…”

Section: Precision Finishing Techniques Used For Fabrication Of Opticmentioning

confidence: 99%

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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Field proven technologies for fabrication of high-precision aspheric and freeform optical surfaces

Cited by 2 publications

References 3 publications

Plasma polishing processes applied on optical materials: A review

Plasma polishing processes applied on optical materials: A review

Review of several precision finishing processes for optics manufacturing

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