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"Optics" means different things to different companies. To AlumiPlate, it means plating of our high purity aluminum onto metal mirrors. The AlumiPlate aluminum layer is then precision diamond machined to a highly reflective surface with a specified finish (~ smoothness) and figure (~ shape). Diamond turned metal mirrors are used in high end optical platforms such as airborne, spaceborne and ground-based infra-red (IR), visible spectrum and multispectral applications. Deterministically produced, low scatter, reflective, aspheric metal components can reduce the number of optical surfaces required in a visible spectrum or IR system while boosting system performance. AlumiPlate aluminum is an excellent surface to diamond machine and can save significant time and money in the manufacture of aspheric and other metal mirrors. AlumiPlate aluminum can be diamond machined to a surface finish of better than 20-40 Angstroms (Å) rms. Better, in most cases, than what can be achieved by diamond turning other mirror substrates - either base materials such as 6061-T6 or other aluminum alloys, or plated material such as nickel. These materials require polishing after diamond machining to achieve a surface finish of better than 50 - 70 Å rms. |
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New diamond turning results on AlumiPlate aluminum. |
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Dr. Alan Hedges of II-VI Incorporated is one of the premier diamond turning specialists in the world. Alan and his team at II-VI have provided AlumiPlate with an outstanding 18 angstroms rms diamond turned surface finish on a 2 inch diameter 6061-T6 spherical mirror plated with 0.005" (5 mils) of AlumiPlate™ High Purity Aluminum. Dr. Hedges also diamond turned 36 Å rms surface finishes onto an aluminum plated 3 inch diameter, 5 inch off-axis parabolic mirror. The following chart shows the results that II-VI believes to be repeatable on this exciting new plated aluminum diamond turning layer as well as the surface roughness achieved on unplated 6061-T6 aluminum alloy. |
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Diamond Turning Results: Surface Roughness Data Comparison of 6061 Al with AlumiPlate Aluminum |
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As evidenced by the above, the AlumiPlate electrodeposited aluminum layer is high purity (99.9+%) aluminum which can be diamond machined to a surface finish of typically 2x - 4x better than that achievable with uncoated Al6061 mirrors. In many cases, this can eliminate the need to polish after diamond turning, saving money, time and uncertainty. |
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Better Finish Means Less Scatter |
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The smoother (< 20 - 40 Å rms) surface of diamond machined AlumiPlate aluminum (vs diamond machined electroless nickel, 6061, or beryllium-based substrates) provides a surface with less roughness and less scatter. This allows the application of diamond turned AlumiPlate aluminum plated metal mirrors in shorter wavelength applications - even into the visible wavelengths - enabling the use of net-diamond turned mirrors in multispectral applications. |
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Reduced Diamond Tool Wear |
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To the diamond turners, the relatively soft, low stress AlumiPlate aluminum layer means lower cutting forces are required which saves on diamond tool wear, breakage, and changeout time while yielding a deterministically-produced, repeatable net diamond turned figure without post-polishing. Because AlumiPlate aluminum has virtually no alloying elements or impurities included in the layer, there is a greatly reduced chance of comet-tails, pull-outs, surface pitting, plowing or breakage of diamond cutting tools. |
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Mr. Jim Wing of Precitech (the leading diamond machine tool manufacturer) provided the above 20 angstroms rms diamond turned surface finish on a three inch diameter convex spherical mirror. The part was a 6061-T6 Al substrate electroplated with 0.005" of AlumiPlate™ High Purity Aluminum and was diamond turned on a Precitech Model Optimum 2400 Two-Axis Single Point Diamond Turning Lathe. |
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Related diamond turning articles/breifs available on the web: |
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Acknowledgments: AlumiPlate wishes to thank the above mentioned organizations for their assistance in sharing the results of their talent and hard work. The above shared information does not necessarily constitute an endorsement of AlumiPlate by the organizations mentioned. |
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