Optics for accelerators require extremely low surface roughness (SR) to achieve high reflectivity due to the very short wavelengths of light used. Diamond turning (DT) is one of the leading machining processes for manufacturing optical components, and is widely used because of its high material removal rate and the ability to obtain optical surfaces with a SR of a few nm or less. There have been many studies on the prediction of SR in the DT process, and many SR prediction models have been proposed for the expression of it. However, when the SR is nm or less, the proposed SR prediction models show different results from the actual results. Aluminum has been used as a material for optical components used in the DT process due to its excellent machinability and high reflectivity, and it is a material that has been used as an actual processing material when proposing the SR prediction model. In order to use aluminum mirrors as optical components for accelerators, their SR must be generated to nm or less. In this study, we have compared and analyzed the nanometer SR of two aluminum materials to fabricate Al mirrors used in infrared optical systems for accelerators.
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