Endoscopy is a detection instrument that integrates traditional optics, human engineering, precision machinery, modern electronics, mathematics, and software[1]. Based on whether the shaft can change direction, endoscopes are classified into rigid scopes and flexible scopes. Snake bone is an important component of the flexible scope that enables bending, and its performance significantly impacts the quality of the endoscope. Snake bones include one-piece snake bones and multisegmented snake bones, and one-piece snake bones are simpler and more reliable than multi-segmented snake bones. In this paper, a three-dimensional model of a one-piece snake bone is designed, and the flexural performance of the snake bone is studied by finite element simulation. During the simulation, the material properties of the snake bone are defined, and the actual working state of the snake bone is simulated by applying load. The simulation results of different parameters of the snake bone were compared, and the key parameters of the snake bone structure were optimized.
AlON ceramic is widely used in the fabrication of high-quality infrared optical components, and has broad application prospects in aerospace, transparent armor, and infrared weapon windows. A laser can be applied to the processing of AlON ceramic in order to achieve a more flexible and efficient processing of AlON ceramic. In this paper, laser drilling experiments were carried out on AlON samples to investigate the mechanism of laser processing of AlON ceramic. A two-dimensional simulation model of laser ablation of AlON ceramic was established, and the process of material removal was analyzed. By comparing the experimental results with the theoretical analysis, the effect of defocus distance on the quality of AlON laser processing is analyzed.
Conformal window is a protective and imaging element in the optical system of high speed flying missile. Its surfaces are required to have the ultra-precision level of surface finish and profile accuracy to ensure good imaging quality and excellent aerodynamic. The large size and high steepness of conformal window bring great challenges to the high- precision manufacturing of inside and outside surfaces. In this paper, an ultra-precision grinding process was designed for conformal window with high steepness. The problems existing in the process of machining the inner and outer surfaces of the window were analyzed, and the most suitable grinding methods for the inner and outer surfaces were determined respectively. Furthermore, the ultra-precision grinding process of conformal window were designed and verified in detail. The research of this paper can be used as a guideline for ultra-precision manufacturing of large-size optical components with high steepness.
Polycrystalline aluminum elements with optical surface quality are widely used in optical fields, such as inertial confinement fusion (ICF) fusion target and optical reflection mirrors, etc. However, the surface height difference induced by elastic deformation after cutting strongly affect the surface quality of polycrystalline aluminum precision parts. In this paper, a crystal plasticity finite element (CPFE) model of the single point diamond cutting for bi-crystal aluminum material was firstly established through the software ABAQUS with the VUMAT subroutine. The surface height difference in diamond cutting of bi-crystal aluminum was investigated by the FE simulations. The surface height difference between grains after machining was extracted from the simulation results, and the suppression law of height difference caused by material properties and cutting parameters was investigated, which provides a theoretical basis for realizing high-quality surface control.
Diamond material has been widely used in the manufacture of high performance optical components due to its excellent mechanical and optical properties. CVD diamond can be used as inertial confinement fusion (ICF) target, X-ray lens of the fourth-generation light source, and infrared window, etc. In order to achieve high quality manufacturing of CVD diamond components, laser-induced graphitization technology can be used to improve the machinability of CVD diamond surface. In this paper, the surface generation mechanism of CVD diamond under laser irradiation were studied by molecular dynamics (MD) simulation. Firstly, a model of polycrystalline CVD diamond under laser ablation was established to reveal removal and evolution of surface materials at the atomic level. The MD simulation results with different grain sizes under laser irradiation were compared, and the influence of grain boundaries and grain size on laser graphitization was determined. Finally, the laser machining processes of CVD diamond were simulated under different laser spot diameters, and the influence of laser area on the graphitization degree of CVD diamond surface was analyzed.
The effects of femtosecond laser (wavelength 1035nm, pulse duration 400 fs, pulse repetition rate 1kHz) on the material removal threshold of superalloy was experimentally investigated, specifically the influence of pulse number irradiated on the threshold of superalloy. Irregular bulge structures were found at the bottom of ablation holes. Two sets of material removal thresholds are derived from the value of hole diameter and depth, which are 0.506 J/cm2 , 0.245 J/cm2 , 0.124 J/cm2 , 0.102 J/cm2 , 0.096 J/cm2 and 0.141 J/cm2 , 0.130 J/cm2 , 0.031 J/cm2 , 0.026 J/cm2 , 0.091 J/cm2 for diameter derivation and depth derivation, respectively, for 1, 10, 100, 500 and 1000 pulses. The deduced two sets of thresholds show similar behavior that the threshold sharply decreases with the pulse number and levels out as the pulse number exceeds 100. The phenomenon is due to incubation effects of multi-pulse irradiation on the surface of superalloy and the incubation coefficient for the thresholds calculated by diameter and depth is fitted to be ~0.72 and ~0.77.
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