• Chinese Optics Letters
  • Vol. 21, Issue 4, 043001 (2023)
Haochen Li1, Tianyuan Liu2、*, Yuchao Fu1, Wanxiang Li1, Meng Zhang3, Xi Yang3, Di Song3, Jiaqi Wang3, You Wang3, and Meizhen Huang1
Author Affiliations
  • 1Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • 2Department of Electrical Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • 3Southwest Institute of Technical Physics, Chengdu 610041, China
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    DOI: 10.3788/COL202321.043001 Cite this Article Set citation alerts
    Haochen Li, Tianyuan Liu, Yuchao Fu, Wanxiang Li, Meng Zhang, Xi Yang, Di Song, Jiaqi Wang, You Wang, Meizhen Huang. Rapid classification of copper concentrate by portable laser-induced breakdown spectroscopy combined with transfer learning and deep convolutional neural network[J]. Chinese Optics Letters, 2023, 21(4): 043001 Copy Citation Text show less
    Block diagram of portable LIBS setup.
    Fig. 1. Block diagram of portable LIBS setup.
    Typical spectrum of copper concentrate acquired by portable LIBS apparatus.
    Fig. 2. Typical spectrum of copper concentrate acquired by portable LIBS apparatus.
    Elemental spectral line intensities of the raw spectra of copper concentrates from 11 classes.
    Fig. 3. Elemental spectral line intensities of the raw spectra of copper concentrates from 11 classes.
    PCA plot of the raw spectra of copper concentrates from 11 classes.
    Fig. 4. PCA plot of the raw spectra of copper concentrates from 11 classes.
    Steps for conversion of 1D spectra to 2D matrix.
    Fig. 5. Steps for conversion of 1D spectra to 2D matrix.
    Schematic diagram of 2D spectrum (left) and 2D spectrum image (right).
    Fig. 6. Schematic diagram of 2D spectrum (left) and 2D spectrum image (right).
    Training process of the four CNN models.
    Fig. 7. Training process of the four CNN models.
    Confusion matrices of the four CNN models on the test set (two upper panels, VGG16 and ResNet18; two lower panels, DenseNet121 and InceptionV3).
    Fig. 8. Confusion matrices of the four CNN models on the test set (two upper panels, VGG16 and ResNet18; two lower panels, DenseNet121 and InceptionV3).
    Comparison of classification accuracy between CNN models and traditional machine-learning models on the test set.
    Fig. 9. Comparison of classification accuracy between CNN models and traditional machine-learning models on the test set.
    Schematic diagram of the spectral features selected by the CST methods.
    Fig. 10. Schematic diagram of the spectral features selected by the CST methods.
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    Mass fraction (%)18.8619.6820.5821.8022.4923.6624.4225.5226.2127.7327.62
    Table 1. Copper Contents of the Copper Concentrate Samples
    ModelTraining AccuracyValidation AccuracyTest Accuracy
    VGG1673.4%82.2%79.9%
    ResNet1871.8%68.6%69.3%
    DenseNet12176.4%59.1%51.1%
    InceptionV370.7%65.9%65.5%
    Table 2. Performance of the CNN Models with the Convolutional Layers Frozen and Only Fully Connected Layers Trained
    ModelTraining AccuracyValidation AccuracyTest Accuracy
    VGG1699.7%95.1%96.2%
    ResNet18100%94.7%92.8%
    DenseNet121100%94.3%93.6%
    InceptionV3100%93.6%93.6%
    NPT-VGGa99.1%88.63%89.4%
    NPT-ResNet100%85.2%83.3%
    NPT-DenseNet100%62.1%61.4%
    NPT-Inception100%80.7%81.1%
    Table 3. Performance of the CNN Model with the Convolutional Layer Unfrozen and Trained with All Parameters
    ModelTraining AccuracyValidation AccuracyTest Accuracy
    PCA-BPNN100%92.5%91.3%
    PCA-SVM98.7%89.8%85.2%
    CST-BPNN100%92.4%90.5%
    CST-SVM100%88.3%87.5%
    Table 4. Performance of the Four Machine-Learning Models
    Haochen Li, Tianyuan Liu, Yuchao Fu, Wanxiang Li, Meng Zhang, Xi Yang, Di Song, Jiaqi Wang, You Wang, Meizhen Huang. Rapid classification of copper concentrate by portable laser-induced breakdown spectroscopy combined with transfer learning and deep convolutional neural network[J]. Chinese Optics Letters, 2023, 21(4): 043001
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