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Single-crystal silicon carbide has excellent electrical, mechanical, and chemical properties. However, due to its high hardness material properties, achieving high-precision manufacturing of single-crystal silicon carbide with an ultra-smooth surface is difficult. In this work, quantum dots were introduced as a sacrificial layer in polishing for pulsed-ion-beam sputtering of single-crystal SiC. The surface of single-crystal silicon carbide with a quantum-dot sacrificial layer was sputtered using a pulsed-ion beam and compared with the surface of single-crystal silicon carbide sputtered directly. The surface roughness evolution of single-crystal silicon carbide etched using a pulsed ion beam was studied, and the mechanism of sacrificial layer sputtering was analyzed theoretically. The results show that direct sputtering of single-crystal silicon carbide will deteriorate the surface quality. On the contrary, the surface roughness of single-crystal silicon carbide with a quantum-dot sacrificial layer added using pulsed-ion-beam sputtering was effectively suppressed, the surface shape accuracy of the Ø120 mm sample was converged to 7.63 nm RMS, and the roughness was reduced to 0.21 nm RMS. Therefore, the single-crystal silicon carbide with the quantum-dot sacrificial layer added via pulsed-ion-beam sputtering can effectively reduce the micro-morphology roughness phenomenon caused by ion-beam sputtering, and it is expected to realize the manufacture of a high-precision ultra-smooth surface of single-crystal silicon carbide. [ABSTRACT FROM AUTHOR]

Ultra-precision shaft components are widely used, such as the shaft core of air-floating spindle, etc. At present, the final precision of such workpieces are difficult to reach through CNC machining tools, but often with the help of manual grinding, of which the machining precision and efficiency are greatly limited. Based on the deterministic figuring method, this paper uses an abrasive belt polishing machine to carry out ultra-precision figuring experiments on shaft parts. On this basis, an ultra-precision composite machine tool for shaft parts is designed with the functions of turning, grinding and abrasive belt polishing. The dynamic performance requirements of the machine tool are put forward by analyzing the precision index of the workpiece and the error control principle of deterministic figuring, and the structure of machine tool is designed and the performance parameters of each part are selected. combined with the finite element analysis, the key components are optimized to meet the machining requirements of 0.1μm roundness and 1μm cylindricity on the steel shaft.

Fused silica has become the preferred optical material in the field of inertial confinement fusion (ICF) due to its excellent performance; however, these costly optical elements are vulnerable, and their manufacture is time-consuming. Therefore, the restoration of laser-induced damage for these optical elements is of great value. To restrain the post-restoration raised rim problem in the CO2 laser repair process to improve the restoration quality, the separate influences of key parameters of laser power, irradiation duration, and laser beam diameter on post-restoration pit morphology are compared in combined simulation and experimental studies. An optimized, patterned CO2 laser strategy is proposed and verified; the results indicate that, with the strategy, the rim height decreases from 2.6 μm to 1.52 μm, and maximal photo thermal absorption is decreased from 784.2 PPM to 209.43 PPM. [ABSTRACT FROM AUTHOR]

A set of in situ measurement equipment of large aperture strong light element based on the principle of laser scattering is established. The size and distribution of defects (damage points) can be judged by the laser scattering signal. The maximum scanning range is 700 mm*1000 mm. The type and size of defects are directly obtained by scanning the quartz sample with a diameter of 100 mm. The types of defects are pitting and scratches, and the width of the scratches and the diameter of the pitting are mostly in the range of 0–10μm. The processing time could reach 31.06s. The device can realize the on‐line in situ measurement of large aperture optical elements, and has the advantages of fast response speed and high measurement accuracy. [ABSTRACT FROM AUTHOR]