Mr. Kexian Li Profile

Kexian Li

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Proceedings Article | 29 December 2023 Paper

Improved YOLOv8n model for retinal macular degeneration detection based on multi-scale feature fusion

Wenhao Wei, Yahong Li, Yu Tang, Xufen Xie, Kexian Li, Yafang Song

Proceedings Volume 12975, 129750P (2023) https://doi.org/10.1117/12.3015652

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To solve the problem that the type and area of macular disease are not easy to identify due to the irregular scale and unobvious characteristics of macular disease region on retinal OCT images, an improved YOLOv8n macular disease detection model is proposed, and a data set of retinal macular disease detection is established. Firstly, the feature pyramid module of bidirectional weighted feature fusion was added. Secondly, the attention mechanism was introduced. Finally, the novel loss function was replaced. The improved model can complete the multi-scale and irregular multi-objective training task of retinal maculopathy. The experimental results show that the improved model has a good effect on the self-built data set. The accuracy of central serous macular degeneration, macular hole, and choroidal neovasculation can reach 97.7%, 97.8%, and 97.4%, respectively, and can accurately identify the location of the lesion.

Proceedings Article | 24 November 2023 Paper

Three-dimensional polarization ray-tracing Mueller algorithm for an optical system with arbitrary surface type

Yahong Li, Kexian Li, Xiangwei Zeng, Yuegang Fu, Peter J. Bryanston-Cross

Proceedings Volume 12935, 1293553 (2023) https://doi.org/10.1117/12.3008229

KEYWORDS: Polarization, Interfaces, Geometrical optics, Mueller matrices, Optical surfaces, Reflection, Polarized light, Incident light, Ray tracing, Matrices

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In order to investigate the relationship between the interface parameters of an optical interface/system and its polarization characteristics, a three-dimensional (3D) polarization ray-tracing Mueller algorithm is proposed in this paper. Firstly, using the optical design simulation software CODE V or ZEMAX, the vector modeling of the optical system and the pupil sampling or field of view sampling of the incident light are carried out. Secondly, according to the surface type of each optical interface in the optical system and whether the optical coating is plated, the 3D polarization ray-tracing of each optical interface is carried out, and the 3D Mueller matrix M_l (9×9 order) of each optical interface under the respective local coordinate system is calculated. Then, a 3×3 order rotation transformation matrix R is introduced by using the rotation transformation of the global coordinate system, and the 3D Mueller matrix M_g (9×9 order) of each optical interface under the global coordinate system is obtained. Based on the 3D polarization algorithm proposed in our published paper, the 3D Mueller matrix M of each sampled ray through whole optical system is calculated. Finally, if the polarization state of the incident light of the optical system is known, the polarization state of the emitted light can be accurately calculated. Especially, the 3D polarization ray-tracing Mueller algorithm is not only suitable for handle the totally, partial and unpolarized light through the optical system, but also suitable for quantitative calculation of the polarization properties of an arbitrary surface, including spherical/aspherical/free-form surface.

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