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Abstract: TiO2 films deposited by electron beam evaporation with glancing angle deposition (GLAD) technique were reported. The influence of flux angle on the surface morphology and the microstructure was investigated by scanning electron microscopy. The GLAD TiO2 films are anisotropy with highly orientated nanostructure of the slanted columns. With the increase of flux angle, refractive index and packing density decrease. This is caused by the shadowing effect dominating film growth. The anisotropic structure of TiO2 films results in optical birefringence, which reaches its maximum at the flux angle α =65°. The maximum birefringence of GLAD TiO2 films is higher than that of common bulk materials. It is suggested that glancing angle deposition may offer an effective method to obtain tailorable refractive index and birefringence in a large continuous range. [Copyright &y& Elsevier]

Computer-controlled sub-aperture polishing technology is limited by its propensity to introduce mid-spatial-frequency (MSF) error (ripple error), which significantly inhibits the performance improvement of the optical system. Here, we propose a novel processing form of the magnetorheological finishing (MRF) tool and its generation mechanism. There are specific path angles and steps, with only tens of microns bandwidth ('magic' angle step), under which a surface without significant path ripple can be stably realized without affecting the convergence of other frequency errors. The magic angle step is precisely obtained via the scale-variant filtered spectrum analysis. Using the two-dimensional (2-D) Taylor approximation of the tool influence function (TIF), we verify that in the magic angle step state, owing to the shape asymmetry and the edge discontinuity of the TIF, the convolution of TIFs presents a complementary effect. It is first observed in experiments that the MSF error can be abnormally increased by decreasing the path step around the magic angle step state. Therefore, the magic angle step and corresponding analysis model have the potential of being extended to other polishing tools. Furthermore, they can significantly benefit the manufacturing efficiency of high-power laser systems, huge telescopes, and lithography systems, as well as improve existing polishing technologies. Image 1 • The magic angle-step processing form of MRF tool has been found to stably realize ripple-free surface. • The MSF error can be increased abnormally with the decrease of path step around magic angle-step state. • The mathematical analysis is presented to obtain the magic angle-step precisely and explain the phenomenon mathematically. • Most of the polishing tools have magic step state, and the tools with rotational asymmetry TIF have magic angle state. [ABSTRACT FROM AUTHOR]