Fig. 1. Design of optical experiment platform

Fig. 2. Overall network structure. (a) Conv block; (b) dense block; (c) DenseUnet; (d) DCNN

Fig. 3. ReLU nonlinear activation function

Fig. 4. Physical diagram of multimode optical fiber imaging system

Fig. 5. Digital images in imaging system performance test experiment

Fig. 6. Results of reconstruction and classification

Fig. 7. Classification accuracy of training set and validation set for reconstructed images under 0.1 m fiber

Fig. 8. Reconstruction accuracy under different fiber lengths. (a) 0.1 m; (b) 10 m

Fig. 9. Classification accuracy of different fiber lengths in training set and validation set. (a) 0.1 m; (b) 10 m

Fig. 10. Results of speckle reconstruction under different fiber lengths

Fig. 11. Comparison of reconstruction results of different network models. (a) Speckle images output from multimode fiber; (b) reconstruction results of DenseUnet; (c) reconstruction results of traditional Unet; (d) original image (ground truth)