Prof. Ci Song Profile

Prof. Ci Song

at National Univ of Defense Technology

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Publications (9)

Proceedings Article | 13 November 2024 Paper

Study on magnetorheological polishing processing characteristics of different crystal planes of SiC

Yunheng Chen, Ci Song, Bo Wang, Dongyang Qiao, Wanli Zhang, Xing Peng, Hailun Si, Jianglin Long

Proceedings Volume 13280, 132800F (2024) https://doi.org/10.1117/12.3046337

KEYWORDS: Silicon carbide, Surface finishing, Silicon, Polishing, Crystals, Abrasives, Chemical species, Chemical mechanical planarization, Semiconducting wafers

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Proceedings Article | 11 October 2024 Paper

Theory and method of pulsed ion beam single crystal silicon reshaping based on controllable time-varying removal function

Rongjie Liao, Tengduo Qiao, Ziyao Tian, Yuyang Wang, Guanlin Li, Dongyang Qiao, Ci Song, Xing Peng

Proceedings Volume 13278, 1327803 (2024) https://doi.org/10.1117/12.3032022

KEYWORDS: Ion beams, Beam diameter, Optical components, Optical surfaces, Polishing, Genetic algorithms, Mirror surfaces, Ions, Surface finishing, Design

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With the continuous improvement of optical performance requirements, weaponry, space observation, laser fusion, extreme ultraviolet lithography, and other fields of optical components of increasing precision requirements, the number of requirements is increasingly large, so the processing of optical components faces serious challenges. Pulsed Ion Beam Shaping is a non-contact optical component machining technology. Pulsed Ion Beam Shaping has the advantages of atomic-level machining accuracy and no edge effect. The ability of pulsed ion beam reshaping mainly depends on factors such as the stability of the removal function, the dynamic performance of the machine's motion axes, and the size of the removal function. At present, due to the difficulty of further improving the dynamic performance of the machine tool, a single beam diameter, and removal efficiency of the removal function for processing, trimming efficiency is not high, and can only be balanced according to the needs of trimming efficiency and accuracy. Thus, we proposed a pulsed ion beam reshaping processing method based on a controlled removal function to achieve the optimal beam diameter selected by the removal function according to the different reshaping face shapes, which improves the reshaping capability of the pulsed ion beam while reducing the additional material removal layer to ensure high processing efficiency. The main research on the shaping method based on the controlled time-varying removal function is carried out, the shaping model based on the controlled time-varying removal function and the residence time solution model are analyzed, the global optimization algorithm based on the error distribution of the surface shape and the removal function library, and the optimal combination of the removal function under the constraints is established, and the theory of the shaping of the controlled time-varying removal function is perfected, and the iterative genetic algorithms, variation and crossover design are used to find the optimal beam diameter according to different shapes of the surface, to improve the processing efficiency. The genetic algorithm is used to iterate the genetic algorithm at different processing points, and the mutation and crossover design is used to find the optimal solutions at different processing points, and the processing is carried out after the optimal solutions are obtained to get the corresponding results, and the two variables of the beam diameter and time are matched during the processing, so as to achieve the maximum improvement of the processing efficiency and the accuracy of the shape trimming. The simulation results show that the controlled time-varying pulsed ion beam reshaping method reduces the residence time by 30 % compared with the conventional ion beam reshaping, the efficiency is 19% higher than that of traditional processing and the facet accuracy reaches 5 nm level.

Proceedings Article | 22 December 2023 Paper

Research on small-size laser damage repairing process for fused silica optics

Wanli Zhang, Dongyang Qiao, Feng Shi, Ci Song, Bo Wang, Yaofei Zhang, Chi Luo

Proceedings Volume 12974, 129740J (2023) https://doi.org/10.1117/12.3015273

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Fused silica optics, as key components in high - power laser systems, are prone to produce laser damage with different sizes under laser irradiation. For large - size laser damage, CO₂ laser can be used for repairing process. For small - size laser damage, magnetorheological finishing (MRF) technique is appropriate. This work focused on the MRF repairing process of small - size laser damage on fused silica optical surface, the optimization of MRF processing parameters and the absorption characteristics of optics are investigated. First, the MRF processing parameters were determined by experimental method. Under the conditions of a wheel speed 200 rpm, flow rate 110 L/min, current 7.5 A, press depth 0.3 mm and polishing abrasive CeO₂, the volumetric removal efficiency of removal function was relatively high, up to about 1.108 mm³/min. Appling the optimized parameters in small - size laser damage repairing process, no "comet tail" defects occurred on the optical surface. After MRF repairing process, the surface roughness was restored by immersed CCOS (computer control optical surfacing) technique. For immersed CCOS process, it contained two stage: coarse polishing and fine polishing. With 120 min of coarse polishing and 40 min of fine polishing, the roughness Ra decreased from the initial 6.179 nm to 0.7 nm, which was basically restored to the initial state. Finally, the photo - thermal absorption of the optics before and after repairing process was detected on a weak absorption testing platform. The results showed that the surface absorption decreased from the initial 425.38 ppm to 125.92 ppm, and the laser energy absorption of the repaired fused silica optics was significantly reduced, which verified the validity of the combined process of MRF and immersed CCOS process. In a conclusion, the research results in this paper can provide important technical support for the rapid repairing of small - size laser damage on fused silica optical surfaces, which was conducive to improving the service life of high - power laser systems.

Proceedings Article | 6 November 2023 Paper

Research on the magnetorheological polishing random rotation technology applied to restrain the mid-spatial frequency waviness errors of high-power laser elements

Hailun Si, Ci Song, Bo Wang, Feng Shi, Guipeng Tie, Ye Tian, Shuo Qiao

Proceedings Volume 12921, 129214M (2023) https://doi.org/10.1117/12.2691856

KEYWORDS: Polishing, Surface finishing, High power lasers, Error analysis, Optical components, Optical surfaces

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Proceedings Article | 6 November 2023 Paper

First principle calculation of damage characteristics of fused silica containing structural defects under short-pulse laser irradiation

Wanli Zhang, Feng Shi, Ci Song, Ye Tian, Bo Wang, Huiping Rong, Yaoyao Ren, Shuangpeng Guo

Proceedings Volume 12921, 129214K (2023) https://doi.org/10.1117/12.2691844

KEYWORDS: Laser induced damage, Fused quartz

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Proceedings Article | 6 November 2023 Paper

Simulation study on the flow field characteristics of abrasive water jet polishing at different angles based on fused quartz laser element

Zhiqiang Zhang, Ci Song, Feng Shi, Guipeng Tie, Wanli Zhang, Bo Wang, Ye Tian

Proceedings Volume 12921, 129214J (2023) https://doi.org/10.1117/12.2691840

KEYWORDS: Nozzles, Abrasives, Polishing, Surface finishing, Optical components, Particles, Laser damage threshold, Fused quartz

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Proceedings Article | 4 April 2023 Paper

Optical system design for collimating beam combiner based on compound eye lens with free-form surface

Zhekai Wang, Shanshan Wang, Qun Hao, Xiao Shen, Feng Shi, Ye Tian, Dede Zhai, Guipeng Tie, Ci Song

Proceedings Volume 12617, 126174O (2023) https://doi.org/10.1117/12.2666373

KEYWORDS: Zernike polynomials, Fiber lasers, Beam diameter, Optical surfaces, Design and modelling, Laser applications, Laser energy

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Limited by the theoretical output power limitation of single-mode fiber laser, achieving higher laser output power requires us to turn to using laser beam combination technology. The current beam combining methods can mainly be divided into spectral beam combining and aperture beam combining. The former method has the advantages of better optical quality, but the beam combining grating bears too much laser energy density and is limited by wavelength selection and scalability. The collimated beam combining method performs better at scalability and shows more uniform energy density, while the beam quality is seriously affected by decrease of optical axis uniformity caused by the thermal deformation of the mechanical cylinder shell, so the problem of laser heat deposition should be solved urgently. Considering that the laser is a Gaussian beam, there is still a small amount of energy beyond the waist radius, so an attempt was made to design a collimating beam scheme with the laser emitting end face as a whole continuous compound eye lens to replace the traditional discrete collimating unit. Zernike polynomial is a classical polynomial to describe optical surface figure. It is consistent with the description form of optical geometric aberration, and its unit orthogonality ensures that changing the number of polynomial terms will not change the original coefficients, which shows its excellent characteristics in optical surface fitting. Continuous compound eye lens is a freeform lens contains several aspheric collimating elements. In the design, according to the geometric characteristics of the distribution of each collimating unit, the basic Zernike polynomial structure can be optimized, and the best fitting number of terms which reaches the balance between the changing of Zernike polynomial terms and the accumulated calculation rounding error has been found. The simulation results of the fitting surface figure using seven channels laser beam show that when the diameter of a single lens is 30mm and the center distance is 80mm, there are 125 terms of optimized effective Zernike polynomials involved in surface fitting, equivalent to 1318 basic Zernike polynomials, and satisfying surface fitting results are obtained. Within each collimating unit, PV error is 53.6 nm, and RMS error is 1.1 nm, exceeding the requirements of manufacturing conditions. The analysis of the error distribution shows that the fairly large PV error is concentrated at the edge of the collimating unit, which has little influence on the laser energy transmittance, which shows the designed compound eye lens can meet the expected transmittance and optical surface figure fineness theoretically. In fact, using continuous compound eye lens as the laser emission end face of the collimator can keep the outgoing optical axis exactly consistent after continuous working with the thermal deformation, owing to its each collimating unit is measured and modified at the same benchmark, which ensured the whole system has higher stability, higher structural reliability and better laser tolerance. This design is recommended to be applied into wireless laser energy transmission, space laser communication and laser detection field.

Proceedings Article | 21 March 2023 Paper

Design of a wide-angle, ultra-thin planar two-dimensional geometrical waveguide combiner

Ningye Ruan, Feng Shi, Ci Song, Ye Tian, Xing Peng, Zhai Dede

Proceedings Volume 12595, 1259528 (2023) https://doi.org/10.1117/12.2669068

KEYWORDS: Waveguides, Design and modelling, Planar waveguides, Mirrors, Light wave propagation, Reflection, Projection systems, Mirror surfaces, Discontinuities, Near eye displays, Augmented reality

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Proceedings Article | 13 December 2021 Paper

Optical mirror surface shape on-site measurement based on reverse Hartmann test

Bowen Xu, Shanshan Wang, Ci Song, Yinlong Hou, Feng Shi, Qun Hao

Proceedings Volume 12071, 1207110 (2021) https://doi.org/10.1117/12.2604316

KEYWORDS: Mirrors, LCDs, Sensors, Head, Image processing, Cameras, Phase shifts, Image acquisition, Inspection, CMOS cameras

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