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• The phenomena of laser energy deposition and light-field enhancement caused by ripple structures was cleared through FEM simulation. • A combined technique of low–stress CCOS and IBF was used to polishing ripple–structure optical surface, and its suitability was verified for fused silica laser optics. • The changes of anti-laser damage characteristics at different processing stage were studied. The correlation between processing parameters, photo-thermal absorption, laser induced damage threshold was cleared. In AMRF (arrayed magnetorheological finishing) process of fused silica laser optics, ripple structures would generate on the optical surface. The ripple structures could cause nonlinear self-focusing and localized energy deposition, finally induced laser damage. In this work, the removal of ripple structures and the improvement of anti-laser damage characteristics were studied. First, the heat deposition and light-field enhancement induced by ripple structures were analyzed by finite element simulation method, and the negative impact of ripple structures was clarified. Then, the ripple-structure surface was polished by a combined technique of low-stress CCOS (computer control optical surfacing) and ion beam finishing (IBF). After the combined polishing process, the ripple structures and the hydrolyzed layer on the surface were removed, the photo-thermal absorption decreased from 0.736 ppm to 0.124 ppm, and the laser induced damage threshold (LIDT) increased from 6.3 J/cm2 to 7.4 J/cm2. In this work, the combined technique was able to remove the ripple structures while maintaining the processing efficiency, and it also could improve the anti-laser damage characteristics of the optics. The relative research results had important reference value for ultra-precision manufacturing of large-aperture laser optics. [ABSTRACT FROM AUTHOR]

• A PSD (Power Spectral Density) analysis method based on the contour of removal function was proposed for AMRF technique. • A new polishing path called "non-equal-interval parallel raster path" customized for AMRF technique was proposed and applied to control mid-spatial-frequency ripple error. • Simulation and actual experiment verified the effects of analysis method and polishing path. With the continuous development of high-power laser systems, laser optics gradually changed towards large-aperture, high-quality. To adapt to the fabrication of large-aperture laser optics, a new-type array magnetorheological finishing (AMRF) technique was developed and had made initial progress. However, AMRF technique would introduce more obvious ripple structures (such as 1 mm−1 of spatial frequency) compared to original MRF technique while adopting conventional raster path, and the ripple structures might affect laser beam transmission. For the further application of AMRF technique, the formation mechanism of ripple structures was studied, and a method based on the contour of removal function was proposed to analyze the changes of spatial frequency and evaluate the effect of different polishing paths. According to the analysis method, non-equal-interval parallel raster path was chosen and applied into AMRF process, along with maintaining efficiency while controlling ripple structures. In general, this work could provide a valuable support for the AMRF process of large-aperture laser optics and had a certain significance for the high-power laser system. [ABSTRACT FROM AUTHOR]

• Infrared optical properties optimization of various Si lattice structures are investigated. • Close-to-atomic method(IBF and CMP) is imported to regulate various lattice layers on Si surface. • Removal of amorphous layer above the low-density layer improve the reflectivity notable. • Low-density(about 1 nm) layer and transition layer(about 1 nm) are conducive for optimize the infrared optical properties(reflectivity and photo-thermal absorption). A fundamental challenge in optimizing the infrared optical properties of monocrystalline Si(1 0 0) reflectors is achieving high infrared reflection and low photo-thermal absorption. These requirements have been traditionally satisfied by removing various surface defects to obtain a perfect lattice structure. To supersede the traditional logic of "non-defect surfaces," a surface lattice structure scheme, "Si lattice layer regulation," is proposed. This paper presents a close-to-atomic-scale method for regulating multilayer Si lattices. First, a "multilayer lattice" (disordered, low-density, and transition layers) is introduced by ion beam figuring as a regulation base. Subsequently, the infrared optical properties are improved by reducing the disordered layer above the low-density layer using chemical–mechanical polishing. An experimental comparison proves that the scheme is effective: the reflectivity of the new surface developed in this study increases by 10 % (from 900 to 1500 nm (testing band)), and the photo-thermal absorption of the surface is controlled at 0.116 ppm. Therefore, the optical properties of monocrystalline Si can be optimized by regulating the thickness of the Si atomic layers with different densities. A lattice layer based on the field of materials science (e.g., material band gap and electronic property regulation) is introduced to an optical field with high infrared optical properties on Si surfaces. This allows the optical processing to enter an emerging "close-to-atomic-scale" manufacturing dimension. This work also opens up advanced prospects in the fields of high-energy optics and X-rays and directs research on atomic structure regulation toward a completely new area of optics. [ABSTRACT FROM AUTHOR]

• The development of new-type arrayed MRF equipment was conducted through theoretical analysis, simulation and experiment. • High removal efficiency of 2.03 × 107 μm3/min and stability better than 5 % were achieved. • Actual experiment verified the effects of arrayed MRF equipment. Along with the continuous development of optical systems, the fabrication of optics gradually moved towards large aperture and high quality. To meet the requirements of optical systems, advanced technologies represented by magnetorheological finishing (MRF) were applied in the processing of optics. According to the background of high-efficiency processing, this work focused on the design of arrayed magnetorheological equipment, including magnetic field theoretical analysis, magnetic field simulation, equipment construction, removal function preparation and stability test. Through the study, arrayed MR (magnetorheological) equipment was preliminarily built and the removal function was prepared. The volume removal rate of arrayed removal function was 2.03 μm3/min after detection, which was 1.35 times of electromagnetic equipment under the same process parameters, and the stability of the removal function was better than 5 %. The results of two-dimensional removal experiment also verified that arrayed MR equipment could significantly improve materials removal efficiency. Based on the experimental results in this work, it is believed that arrayed MR equipment have certain advantages in the improvement of processing efficiency and surface quality, and it could meet the requirement of optical processing at the present stage. The relevant design theories and methods could provide reference to the follow-up research. [ABSTRACT FROM AUTHOR]