To meet the requirements for lightweight, miniaturized dispersive optical systems for space applications, linear variable filters with a high transmittance and spatial dispersion coefficient are proposed. The filters were produced with dual ion beam sputtering, where a single layer thickness variation was achieved with a deposition rate adjustment based on a linear variable correction formula. A linear variable trend matching method was used to correct the film thickness based on the reduction of the mismatch error between two materials: Ta₂O₅ and SiO₂. The influence of the spectral and spatial measuring average effects was addressed by sampling the spot size optimization. This paper presents an all-dielectric linear variable filter that operates between 520 and 1000 nm, with an excellent linear dependence of 40 nm/mm over 12 mm. The linear variable filter possessed a 2.5% bandwidth, and its transmittance was found to be >80% at the central wavelength of the band, with a 0.1% transmittance in the cut-off region. These results indicate great potential for optical devices for space applications, and the developed process has good reproducibility and stability.

HfO₂ thin films were prepared using radio frequency (RF) ion source-assisted deposition, and the effects of auxiliary ion energy on the microstructure, optical properties, and residual stress of the films were systematically studied. The experimental results showed that when the auxiliary ion energy increased, the extinction coefficient, compressive stress, and optical band gap were gradually increased. These changes were attributed to increased grain boundary defects, crystal structure disorder, and grain size decrease due to high-energy ion bombardment. The HfO₂ films deposited at a lower ion energy (600 V) exhibited higher surface quality (RMS = 0.78 nm), better optical properties (k = 10⁻⁵), and lower residual stress (1.26 GPa).

We present a dual-layer hafnium dioxide (HfO₂) grating capable of full-color modulation in the visible spectrum by leveraging the magnetic dipole resonance induced by the lower-layer HfO₂ grating, while the upper-layer HfO₂ grating serves as a refractive index matching layer to effectively suppress high-order Mie resonances at shorter wavelengths. The HfO₂/HfO₂ grating exhibits a significantly larger distribution area in the CIE 1931 chromaticity diagram compared to the HfO₂ grating. Furthermore, the structural color saturation closely approximates that of monochromatic light. Under varying background refractive index environments, this structure consistently exhibits high-quality structural color. However, the hue of the structural color undergoes alterations. When the polarization angle is below 20°, the saturation of the acquired structural color remains remarkably consistent. However, exceeding 20° results in a significant degradation in the quality of the structural color. This study demonstrates the promising potential for diverse applications, encompassing fields such as imaging and displays.

To address the challenge of achieving uniform coating on large-aperture substrates with significant sagittal height differences, this study employs a conventional-sized movable sputtering target combined with substrate rotation to realize high-uniformity control. The research establishes a geometric deposition model for the spatial thickness distribution of thin films on large-aperture, high-sagittal-height substrates and develops a precise control method for the deposition distribution on the substrate surface. Using the gradient descent algorithm, an optimal velocity modulation curve is calculated, and the spatial thickness distribution under this curve is determined. Compared with traditional least-squares optimization, this method effectively overcomes the issues of slow computation speed and poor convergence in large-scale numerical calculations, enabling rapid and uniform spatial control of large-aperture substrates. Calculation results demonstrate that the proposed method reduces the film non-uniformity from over 60% to a final value of 2.66%, with a corresponding PV value of 2.61%, across the 6550 mm aperture, showcasing its high precision.