sub surface damage removal in fabrication

Sub-surface damage issues for eective fabriion of large optics

surfaces having less subsurface damage and at higher material removal rates. To achieve this production capab- ility, a new ultra precision large optics grinder 5 -BoX R - has been developed at

Experimental investigation of surface/subsurface …

2008/5/1· Subsurface damage of the ground specimens, which were prepared using the bonded interface sectioning technique, was examined using an SEM. Two types of subsurface damage, chipping and cracking, induced by grinding were clearly observed.

Sub-surface mechanical damage distributions during …

2005/11/28· Removal of subsurface damage, during the polishing process, requires polishing to a depth which is greater than the depth of the residual cracks present following the shaping process. To successfully manage, and ultimately remove subsurface damage, understanding the distribution and character of fractures in the subsurface region introduced during fabriion process is important.

Geometry and surface damage in micro electrical …

2009/9/24· Geometry and subsurface damage of blind micro-holes produced by micro electrical discharge machining (micro-EDM) is investigated experimentally to explore the relational dependence with respect to pulse energy. For this purpose, micro-holes are machined with various pulse energies on plastic mold steel samples using a tungsten carbide tool

Wet-Etching Evaluation Method of Subsurface …

Recently, grinding process of an optical glass should make surface quality as high as possible in order to reduce removal amount in polishing process. Accordingly, evaluation of subsurface damage induced under various grinding conditions has been required because subsurface damage leads to crack initiation or deterioration of the performance.

Measurement and alleviation of subsurface damage in a …

The alleviation of subsurface machining damage in a thick-crystal neutron interferometer is investigated by testing the interferometer throughout an annealing and chemical etching post-fabriion process. Spatially varying Bragg-plane angular misalignments between diffracting components of the interferometer are lessened from 10−5 rad to less than 10−9 rad.

Mechanisms of subsurface damage and material …

Mechanisms of subsurface damage and material removal during high speed grinding processes in Ni/Cu multilayers using a molecular dynamics study QiHong Fang, Qiong Wang, Jia Li *, Xin Zeng and YouWen Liu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan Province 410082, PR China.

Sub-surface damage issues for effective fabriion of …

2008/7/1· The subsurface damage was revealed using a sub aperture polishing process in coination with an etching technique. These results are compared with the targeted form accuracy of 1 μm p-v over a 1 metre part, surface roughness of 50-150 nm RMS and subsurface damage in the range of 2-5 μm.

US6810887B2 - Method for cleaning semiconductor …

A method for reducing sub-surface damage to a part includes determining how deep is the sub-surface damage beneath a surface of a part; chemically etching said surface of said part; and stopping

RAMAGOPAL V SAREPAKA - Academia.edu

In the fabriion of precision optical and opto-mechanical components by machining, the micro-crack structure generated under the surface is referred to as Sub-Surface Damage (SSD). SSD severely affects the quality and strength of an optical component thus reducing its life.

MICRO: Critical Materials—Wafers

The effect of surface removal is not always straightforward, since polishing affects the subsurface layer and can, to a certain extent, hide deep damage. In fact, since polishing seems to reorder the wafer near the surface, subsurface damage caused by slicing or lapping is not usually immediately evident near the surface.

Sub-surface damage issues for eective fabriion of large optics

surfaces having less subsurface damage and at higher material removal rates. To achieve this production capab- ility, a new ultra precision large optics grinder 5 -BoX R - has been developed at

Subsurface Damage | Edmund Optics

Polishing with finer and finer grits can further reduce the amount of subsurface damage, but this damage cannot be removed completely. Polishing with finer grits improves the quality of the optic, but increases the amount of time required for polishing, which in turn increases cost.

Analysis of subsurface damage during fabriion process …

2012/1/12· Subsurface damage (SSD) in optical components is known to play an important role in restricting the high fluence operation in high power laser systems. Subsurface damage appears inevitably during the shaping, grinding, and polishing process, which are essential in the production of defect-free optical components.

Sub-surface damage issues for effective fabriion of …

2008/7/23· The highest material removal rate (187.5 mm 3 /s) used ensures that a 1 metre diameter optic can be ground in less than 10 hours. The surface roughness and surface profile were measured using a Form Talysurf. The subsurface damage was revealed using a sub

Subsurface Damage (SSD) Assessment in Ground Silicon Carbide …

SiC surfaces. As a result of the material removal process in SiC, for example by grinding, a subsurface damaged (SSD) layer is left in the surface. This layer contains microcracks that may compromise both the optical performance of the surface, as well as its

Process induced sub-surface damage in mechanically …

2008/5/28· Therefore, understanding and minimizing the process induced damage during mechanical grinding is a key factor for the fabriion of ultra-thin wafers. The damage caused by grinding is typically investigated by searching for the possible presence of sub-surface cracks, the measurement of wafer warpage, characterization of mechanical strength and diode reverse leakage current [ 5–10 ].

Sub-surface damage issues for eective fabriion of large optics

surfaces having less subsurface damage and at higher material removal rates. To achieve this production capab- ility, a new ultra precision large optics grinder 5 -BoX R - has been developed at

Subsurface Damage | Edmund Optics

Polishing with finer and finer grits can further reduce the amount of subsurface damage, but this damage cannot be removed completely. Polishing with finer grits improves the quality of the optic, but increases the amount of time required for polishing, which in turn increases cost.

Subsurface Damage (SSD) Assessment in Ground Silicon Carbide …

Abstract: We assess subsurface damage in ground Silicon Carbide, by measurement of roughness evolution and material removal rate in sub-aperture finished spots, or by estimates via material property figures of merit or abrasive size used for grinding. 1.

Critical parameters for grinding large sapphire window panels

Sub-surface damage Bonded-interface specimens and Nomarski microscopy Removal rate Thickness and time measurements The panel samples were first back-side ground and polished, using the current EEO manufacturing process parameters.

Subsurface damage in optical materials: Origin, …

2021/6/2· The detection, measurement and removal of subsurface damage is a major effort of the LLNL Optical Sciences and Engineering Group. We will describe and show examples of three methods we are currently using to detect and measure the depth of damage in glasses and crystalline materials: taper polishing and etching, constancy of chemical etch rate, and small specimen fracture.

High-Efficiency and Low-Damage Lapping Process …

The silica opticsare widely applied in the modern laser system, and its fabriion is always the research focus. In the manufacturing process, the lapping process occurs between grinding and final polishing. However, lapping processes optimizations focus on decreasing the depth of sub-surface damage (SSD) or improving lapping efficiency

Process induced sub-surface damage in mechanically ground …

2019/5/22· preferential etching were used to characterize the sub-surface damage induced by the rough and fine grinding steps used to make ultra-thin silicon wafers. The roughly and ultra-finely ground silicon wafers were examined on both the machined (100) planes and the

Process induced sub-surface damage in mechanically ground …

2019/5/22· preferential etching were used to characterize the sub-surface damage induced by the rough and fine grinding steps used to make ultra-thin silicon wafers. The roughly and ultra-finely ground silicon wafers were examined on both the machined (100) planes and the

The study of sub-surface damage distributions during …

The higher material removal rate (MRR) leads to deeper sub-surface damage (SSD) on lens surface. The SSD must be removed by following lapping and polishing processes to ensure the lens quality. However, these are not an easy and an efficient process to remove the SSD from ground surface directly for aspheric surfaces with tens or hundreds microns departure from bestfit- sphere (BFS).

Fabriion of supersmooth surfaces with low …

To produce super-smooth optical surfaces with extreme low subsurface damage (SSD) is still a challenge in optical fabriion. A systemic method is designed to get the low damage super-smooth surfaces in this paper. By taking the fabriion of supersmooth surfaces as a chain, careful attention is given to each key node of samples fabriion process, the grinding, fine grinding and polishing

A predictive model of subsurface damage and material …

2019/1/29· It has been proven that micro-geometry of abrasive grits can influence the maximum cutting depth, thereby strongly affecting the material removal mechanism in grinding of brittle materials. The influence of grit micro-geometry on subsurface integrity, however, is not yet fully understood. In this paper, we aim to understand how grit micro-geometry affects subsurface damage and the material

Detection and control of subsurface damage of optical …

Considering the effect of etching, we used etching method in fabriion process to remove the polished layer of material, expand the scratch, and expose the subsurface damage. Then we used three kinds of method to detect these samples, and analyzed the relation between subsurface damage and fabriion process.

Thermal healing of the sub-surface damage layer in …

2010/11/1· Savrun et al. have shown that the removal of surface/sub-surface machining damage resulted in a more than twofold increase in the compressive strength of sapphire at 600 C. Crystalline defects in the substrate material such as processing damage and disloions have been reported to influence the electrical properties of epitaxial silicon films in SOS/CMOS appliions [2] .