Ion beam figuring for lithography optics

Weiser, M.

doi:10.1016/j.nimb.2009.01.051

Cited by 113 publications

(43 citation statements)

References 6 publications

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“…Ion beam figuring (IBF) for ultra precision surface finishing is well established in high end optics fabrication for lithography, space and beam-line optics and advanced optical instrument, respectively [1,2]. IBF standard technology uses a constant and stable ion beam that moves computer controlled across the entire optic via a meander like scanning with variable scan line velocity ac-cording to the local dwell time necessary for the specified removal of material at the certain place.…”

Section: Ion Beam Figuringmentioning

confidence: 99%

Tutorial on Recent Advances in Ion Beam and Plasma Jet Processing

Schindler

2012

Imaging and Applied Optics Technical Papers

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The Tutorial will highlight recent advances achieved in R&D of Ion beam figuring (IBF), ion Beam Smoothing (IBS), Reactive Ion Beam Etching (RIBE) and atmospheric Plasma Jet Machining (PJM) (deep aspherization, nanometer shape correction, smoothing, film deposition) at IOM Leipzig. OCIS codes (220.1250) Aspherics; (220.4610) Optical fabrication; (220.5450) Polishing; (350.3850) Materials processing Ion beam figuringIon beam figuring (IBF) for ultra precision surface finishing is well established in high end optics fabrication for lithography, space and beam-line optics and advanced optical instrument, respectively [1,2]. IBF standard technology uses a constant and stable ion beam that moves computer controlled across the entire optic via a meander like scanning with variable scan line velocity ac-cording to the local dwell time necessary for the specified removal of material at the certain place. The beam tool size has to be adjusted according to the spatial surface error size processing. One serious disadvantage of this method is connected with the continuous and constant beam and the limitations in maximum speed and acceleration/deceleration of the mechanical multi axes motion system. This causes wasting of material removal at least in that part of the surface where no material should be removed (absolute minimum of the surface figure). Further there can be some effects of direct additional surface error production in cases of steep gradients and small surface feature sizes of the surface topology where the beam can not follow the very small dwell times due to the limitations of the dynamics of the motion system.The new solution uses a pulsed ion beam instead of a cw one combined with pulse width modulation (PWM) for variation of the mean beam power and the control of the PWM signal by the motion control of the multi axes system that moves the ion beam (source) across the surface to be figured. Using this trick we effectively extend the limited dwell time scale realized by the mechanical motion system by two orders of magnitude to lower values. Figure 1 shows the scheme of the new technique. New IBF processing software (DtCalc) has been developed for a two dwell times algorithm velocity driven and PWM driven, respectively. Ion beam smoothing / ion beam nano-structure generation by atomic self assemblyIn contrast to the stringently deterministic process of ion beam figuring, ion beam induced smoothing of micron and nano meter features is strongly coupled to atomistic processes which are characteristic for the much shorter spatial length scales and are less deterministic. Nevertheless, within the last years low-energy ion beams have been developed as alternative tools that can be beneficially used to tailor the microscopic surface roughness of solid surfaces on a nanometer and micron scale. Recently developed different ion beam assisted processes for the preparation of ultra-smooth surfaces with RMS roughness values r 0.2 nm. Especially, ion beam direct smoothing and smoothing with planarization or sacrificial ...

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Section: Ion Beam Figuringmentioning

confidence: 99%

Tutorial on Recent Advances in Ion Beam and Plasma Jet Processing

Schindler

2012

Imaging and Applied Optics Technical Papers

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“…Present "state of the art" manufacturing procedures for SiC aspherical mirrors are started from successive grinding, followed by computer-controlled subaperture lapping and polishing processes. Afterward, highdeterministic processes such as magnetorheological finishing and ion beam figuring are always used to achieve necessary form accuracy typically less than 100 nm in peak-to-valley (PV) [9][10][11]. The grinding is a high efficiency process, and its material removal rate is about 20∼50 times of that of the subsequent processes.…”

Section: Introductionmentioning

confidence: 99%

High-performance grinding of a 2-m scale silicon carbide mirror blank for the space-based telescope

Zhang

Yang

Zheng

et al. 2016

Int J Adv Manuf Technol

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Silicon carbide (SiC) is a competitive candidate material for building the space-based reflecting mirrors. However, SiC is also a typical difficult-to-machine material due to its extreme hardness. When SiC workpiece is machined by grinding, the wheel wears rapidly which leads to a deterioration of surface form accuracy. Grinding efficiency also becomes extremely low due to the frequent truing and dressing of grinding wheels. To achieve high-performance grinding process capable of producing accurate surface at high grinding efficiency, an ultrasonic vibration-assisted fix-point grinding technology was developed in this study. Wheel wear observation indicated that the wheel needs not to be dressed during the whole grinding cycle. Moreover, a laser tracker was used to achieve an on-machine measurement of the surface form error. A CNC tool microset was adopted to evaluate the wheel wear amount. On the basis of the above two results, surface form error could be predicted before grinding, and thus, an inprocess compensation of surface form error was carried out. Using the above-mentioned grinding strategies, a SiC mirror blank with an aperture diameter of 2 m was successfully ground to a form accuracy of 18 μm in peak-to-valley (PV). Therefore, this work provides an efficient and economical solution for grinding the large-scale SiC aspherical surfaces.

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“…However, further etching often results in a decrease rather than an increase of damage threshold due to impurities re-deposition and surface roughness deterioration [12,13]. Ion-beam sputtering (IBS) based on physical sputtering effect is a kind of highly deterministic processing method, with highly controllable sputtering depth and other advantages such as good anisotropy, low-damage and little stress produced in the target materials [14]. As a clean and noncontact machining technique, IBS can achieve super-smooth surface without introduction of other metal impurities such as Fe element and re-deposition layer on the surface compared with MRF and HF etching [15,16].…”

Section: Introductionmentioning

confidence: 99%