We explored three different surface configurations while designing the aluminum oxide (alumina) surface for use in subsequent experiments. The three surface configurations' fabrication and optical performance are described in S1.1 Surface configurations, nanofabrication, and FECO performance section. Detailed X-ray photoelectron spectroscopy (XPS) for chemical analysis, atomic force microscopy (AFM) for surface roughness, and ellipsometry for the determination of the refractive index of the aluminum and alumina films are provided in the S1.2 Surface chemical analysis and S1.3 Film surface roughness and refractive index analysis sections. Additional characterization consisted of surface stability during curing and aging experiments. The final alumina surface chosen for experiments was stable for at least one week of aging under the experimental conditions tested (humidity 0-100 %RH and immersed, temperature 21-60°C). Furthermore, it was suitable for producing fringes of equal chromatic order (FECO). The surfaces consisted of a 2 nm Ti adhesion-promoting layer, followed by a 42 nm reflective gold layer, followed by a second 2 nm Ti adhesion-promoting layer, and finishing with a 70 -80 nm alumina layer deposited via ion beam deposition (IBD). We call this surface configuration 3. Figures and show the FECO obtained with the common back-silvered mica substrates and the FECO obtained from surface configuration 3.