Advanced Photonics, Volume. 1, Issue 1, 016004(2019)

End-to-end deep learning framework for digital holographic reconstruction

Zhenbo Ren1,2, Zhimin Xu3, and Edmund Y. Lam1、*
Author Affiliations
  • 1University of Hong Kong, Department of Electrical and Electronic Engineering, Pokfulam, Hong Kong, China
  • 2Northwestern Polytechnical University, School of Natural and Applied Sciences, Xi’an, China
  • 3SharpSight Limited, Hong Kong, China
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    Figures & Tables(14)
    (a) Schematic of the deep learning workflow and the structure of HRNet. It consists of three functional blocks: input, feature extraction, and reconstruction. In the first block, the input is a hologram of either an amplitude object (top), a phase object (middle), or a two-sectional object (bottom). The third block is the reconstructed output image according to the specific input. The second block shows the structure of HRNet; (b) and (c) elaborate the detailed structures of the residual unit and the subpixel convolutional layer, respectively.
    (a) The USAF test target and its local areas as amplitude objects. (b) A customized groove on an optical wafer as the phase object. (c) A homemade two-sectional object consisting of a transparent triangle and a rectangle located at different axial positions.
    Experimentally collected testing holograms of amplitude objects.
    (a)–(d) Ground-truth images and reconstructed images of holograms in Fig. 3 using (e)–(h) HRNet, (i)–(l) ASM, and (m)–(p) CONV.
    Experimentally collected testing holograms of the phase object.
    (a)–(d) Ground-truth images and reconstructed quantitative phase images of holograms in Fig. 5 using (e)–(h) HRNet, (i)–(l) PCA, and (m)–(p) DE. The unit of the color bar is radian.
    Experimentally collected testing holograms of the two-sectional object.
    Ground-truth: (a)–(d) EFI and (e)–(h) DM. HRNet, reconstructed: (i)–(l) EFI and (m)–(p) DM. Entropy, reconstructed: (q)–(t) EFI and (u)–(x) DM. T-gradient, reconstructed: (y)–(ab) EFI and (ac)–(af) DM. Variance, reconstructed: (ag)–(aj) EFI and (ak)–(an) DM. The color bar shows the depth in DM; the unit is mm.
    (a) and (b) Holograms. (c) and (d) Frequency spectra. (e) and (f) Reconstructed images under different angles.
    Holograms [(a) and (b)] and reconstructed images [(c) and (d)] under different axial distances.
    • Table 1. Comparison of reconstruction performance for the amplitude object among ASM, CONV, and HRNet.

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      Table 1. Comparison of reconstruction performance for the amplitude object among ASM, CONV, and HRNet.

      MeasureMethodsAmplitude dataset
      ValidationTest
      PSNR (dB)ASM17.6619.64
      CONV19.6820.54
      HRNet25.9924.62
      SSIMASM0.200.19
      CONV0.260.26
      HRNet0.920.91
      Time (s)ASM1.561.49
      CONV1.351.72
      HRNet1.141.21
    • Table 2. Comparison of reconstruction performance for the phase object among PCA, DE, and HRNet.

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      Table 2. Comparison of reconstruction performance for the phase object among PCA, DE, and HRNet.

      MeasureMethodsPhase dataset
      ValidationTest
      PSNR (dB)PCA10.129.53
      DE8.948.68
      HRNet30.3530.49
      SSIMPCA0.130.11
      DE0.120.10
      HRNet0.960.96
      Time (s)PCA1.961.93
      DE2.092.15
      HRNet1.061.20
    • Table 3. Comparison of EFI and DM reconstruction performance for the two-sectional object among SEN, VRA, TEN, and HRNet.

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      Table 3. Comparison of EFI and DM reconstruction performance for the two-sectional object among SEN, VRA, TEN, and HRNet.

      MeasureMethodsEFIDM
      ValidationTestValidationTest
      PSNR (dB)SEN16.8215.9212.6612.78
      VAR15.4414.6912.7811.92
      TEN16.0315.8611.8212.24
      HRNet35.6435.7237.8136.70
      SSIMSEN0.280.270.800.80
      VAR0.100.110.820.82
      TEN0.140.100.800.80
      HRNet0.970.970.970.98
      Time (s)SEN380.30392.68390.03391.36
      VAR384.38386.52390.58388.82
      TEN376.76383.66398.29394.37
      HRNet1.351.301.041.42
    • Table 4. Detailed description of the layers and parameters of the proposed HRNet (biases are ignored in the computation).

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      Table 4. Detailed description of the layers and parameters of the proposed HRNet (biases are ignored in the computation).

      Layer numberLayer typeConfigurationNumber of parameters
      Layer 12-D convolution3 × 3 × 32 + BN + ReLU3 × 3 × 32 = 288
      Layer 2ResUnit (64)Max-pooling: 2 × 2 3 × 3 × 64 + BN + ReLU 3 × 3 × 64 + BN + ReLUParameter-free 3 × 3 × 32 × 64 = 18,432 3 × 3 × 64 × 64 = 36,864
      Layer 3ResUnit (64)3 × 3 × 64 + BN + ReLU 3 × 3 × 64 + BN + ReLU3 × 3 × 64 × 64 = 36,864 3 × 3 × 64 × 64 = 36,864
      Layer 4ResUnit (128)Max-pooling: 2 × 2 3 × 3 × 128 + BN + ReLU 3 × 3 × 128 + BN + ReLUParameter-free 3 × 3 × 64 × 128 = 73,728 3 × 3 × 128 × 128 = 147,456
      Layer 5ResUnit (128)3 × 3 × 128 + BN + ReLU 3 × 3 × 128 + BN + ReLU3 × 3 × 128 × 128 = 147,456 3 × 3 × 128 × 128 = 147,456
      Layer 6ResUnit (256)Max-pooling: 2 × 2 3 × 3 × 256 + BN + ReLU 3 × 3 × 256 + BN + ReLUParameter-free 3 × 3 × 128 × 256 = 294,912 3 × 3 × 256 × 256 = 589,824
      Layer 7ResUnit (256)3 × 3 × 256 + BN + ReLU 3 × 3 × 256 + BN + ReLU3 × 3 × 256 × 256 = 589,824 3 × 3 × 256 × 256 = 589,824
      Layer 8Subpixel convolution3 × 3 × 64 + BN + ReLU + periodic shuffling3 × 3 × 256 × 64 = 147,456
      Total parameters2,857,248
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    Zhenbo Ren, Zhimin Xu, Edmund Y. Lam, "End-to-end deep learning framework for digital holographic reconstruction," Adv. Photon. 1, 016004 (2019)

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    Paper Information

    Category: Research Articles

    Received: Jun. 6, 2018

    Accepted: Nov. 14, 2018

    Published Online: Feb. 18, 2019

    The Author Email: Lam Edmund Y. (elam@eee.hku.hk)

    DOI:10.1117/1.AP.1.1.016004

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