Surface topography model for ultra-precision diamond machining of the RSA6061 image slicer

Fabricating the Gemini infrared multi-object spectrograph (GIRMOS) image slicer requires ultra-precision diamond machining (UPDM) to achieve nanometric surface quality for astronomical observations. Existing surface topography models lack realism and general modelling in predicting surface generation for complex geometries. This study develops an improved surface topography model for RSA 6061 aluminum image slicers by incorporating refined tool edge profiles, material defects, and post-machining behavior alongside vibration, feed, and tool geometry parameters. Experimental validation of three-slice samples demonstrated excellent agreement with predictions, achieving surface roughness of 3.76-4.1 nm. Power spectral density and profilometry analyses confirm the model's accuracy for UPDM of optical components.