Deterministic optics fabrication using sub-aperture tools has been vital for manufacturing precision optical surfaces, industrial robotic polishing, which is a more economical and intelligent method is required in modern fabrication process. However, the challenge of robotic polishing lies in the widely used spiral and raster paths, which may leave excess waviness from the tool path, and the unavoidable constant removal layer is added to obtain positive dwell time which cause low polishing accuracy. The waviness can be removed by either using smoothing tools sequentially or randomizing the tool path. However, process efficiency and accuracy are not well considered in the existing tool-path planning. A density adaptive path based on a stacked rotation convolution model to ensure polishing accuracy and efficiency while avoiding waviness generation is proposed in this study, and then the dwell time is calculated by anti-aliasing space-variant deconvolution. The robotic polisher experimental results confirm that the root mean square (RMS) of the final surface figure has been successfully reduced and stabilized at 7.355 nm, and the convergence effect at unit wavelength has been significantly augmented with an improvement of 367%, reducing the measurement from 28% to 131%; in addition, no obvious mid-spatial frequency (MSF) peak was generated in the PSD analysis of density adaptive path polishing results. Henceforth, the polishing accuracy, efficiency, and MSF error of robotic polishing can be greatly enhanced.

Laser ablation is widely recognized as a non-contact and contamination-free processing technology for fabricating fused silica optics. However, when machining curved optics, the introduction of incidence and path angles inevitably alters laser beam characteristics and complicates path planning. Due to the complex coupling interactions and unique properties of fused silica, the unclear influence mechanism of these angles on laser ablation has become a bottleneck hindering further advancements. In this study, a three-dimensional multi-physics model was developed to elucidate the underlying influence mechanism. Through comprehensive theoretical simulations, the effects of different incidence and path angles on surface morphology, temperature field, heat-affected zone (HAZ), and thermal stress were systematically investigated. The results demonstrate that the incidence angle modulates ablation quality and thermo-mechanical properties by reducing power density, inducing spot distortion, and lowering material reflectivity. Meanwhile, the path angle influences machining morphology, temperature and HAZ distribution by altering the direction of spot distortion. Additionally, experimental measurements validated the simulation results, demonstrating an average error of 4.81% in ablation depth across incidence angles from 0° to 20°. This work not only deepens the understanding of the laser ablation process but also provides a theoretical foundation for achieving high-quality fabrication of curved fused silica optics.

Sub-aperture polishing is a key technique for fabricating ultra-precision optics. However, the existence of the polishing errors that are difficult to be compensated by physical modeling seriously affects the manufacturing accuracy and efficiency of optical components. To address this problem, a data-based systematic error extraction and compensation (DSEC) method was proposed to enhance the polishing accuracy on optics. To maximize the extraction quality in a small dataset condition, the wavelet transform is introduced into the extraction process, and the uncertainty of the piston term in the interferometer measurement is improved by L1-norm optimization. Furthermore, two typical error sources (loss of polishing fluid in the edge and the robot trajectory error) are used to verify the effectiveness of the proposed method; in experimental verification, the root mean square (RMS) of the surface figure of a ϕ85-mm mirror was decreased from 0.069λ to 0.017λ, and the RMS of the 610 × 440 mm mirrors was achieved at 0.019λ after the edge compensation, where the polishing accuracy can be improved by more than 4 times; additionally, the RMS of the surface figure with an effective aperture of 480 × 360 mm mirror was reached at 0.011λ after the trajectory error compensation, where the polishing accuracy can be improved by more than 2 times. The proposed DSEC model offers insights that will help achieve advancement in the sub-aperture polishing process.

Tunable filters have many potential applications in diverse fields, including high-capacity communications, dynamic beam shaping and spectral imaging. Although providing a high-performance solution for actively tunable devices, metasurface combined with tunable materials faces the great challenges of limited tuning range and modulation depth. Here, we propose a far-infrared tunable band-stop filter based on Fabry-Perot (FP) resonators and graphene surface plasmons. By switching the wavelength of the critical coupling condition of the filter via the gate voltage applied on graphene, achieving the dynamically tunable band-stop filtering at the central wavelengths from 12.4 μm to 14.1 μm with a modulation depth of more than 99%. Due to the symmetry of the proposed meta-atoms, the filter is insensitive to the polarization direction of the incident light. And it can realize more than 85% filtering efficiency within 60° angle of incidence around the vertical direction. By adjusting the geometry of the meta-atoms structure, it is feasible to move the operational range from the near-infrared to terahertz bands.