Optical Coherence Tomography
OCT is a low-coherence interferometric imaging technique that measures depth-resolved backscattering profiles (A-scans) by interfering sample-arm reflections with a reference mirror. In spectral-domain OCT, the interference spectrum is recorded by a spectrometer and the axial profile is obtained via Fourier transform. Axial resolution is determined by the source bandwidth (typically 3-7 um in tissue) and imaging depth by spectrometer resolution. Dominant artifacts include speckle noise, motion artifacts, and sensitivity roll-off with depth.
Low Coherence Interferometry
Speckle
fft recon
SPECTROMETER
Forward-Model Signal Chain
Each primitive represents a physical operation in the measurement process. Arrows show signal flow left to right.
P(low-coherence) → Σ(interference) → D(g, η₁)
Benchmark Variants & Leaderboards
OCT
Optical Coherence Tomography
P(low-coherence) → Σ(interference) → D(g, η₁)
Standard Leaderboard (Top 10)
| # | Method | Score | PSNR (dB) | SSIM | Trust | Source |
|---|---|---|---|---|---|---|
| 🥇 | ScoreOCT | 0.869 | 37.95 | 0.973 | ✓ Certified | Wei et al., ECCV 2025 |
| 🥈 | DiffusionOCT | 0.860 | 37.52 | 0.970 | ✓ Certified | Zhang et al., NeurIPS 2024 |
| 🥉 | SpeckleFormer | 0.846 | 36.85 | 0.964 | ✓ Certified | Devalla et al., ECCV 2024 |
| 4 | RetinalFormer | 0.836 | 36.35 | 0.960 | ✓ Certified | Chen et al., ICCV 2024 |
| 5 | OCT-ViT | 0.831 | 36.12 | 0.958 | ✓ Certified | Tian et al., ICCV 2024 |
| 6 | OCTA-Net | 0.798 | 34.6 | 0.942 | ✓ Certified | Hybrid U-Net+Transformer, 2023 |
| 7 | U-Net-OCT | 0.782 | 33.85 | 0.935 | ✓ Certified | U-Net variant |
| 8 | Speckle-DenoiseNet | 0.764 | 33.1 | 0.925 | ✓ Certified | Devalla et al., BOE 2019 |
| 9 | NLM-OCT | 0.688 | 30.2 | 0.870 | ✓ Certified | Non-local means variant |
| 10 | BM4D | 0.663 | 29.3 | 0.850 | ✓ Certified | Maggioni et al., IEEE TIP 2013 |
Showing top 10 of 13 methods. View all →
Mismatch Parameters (3) click to expand
| Name | Symbol | Description | Nominal | Perturbed |
|---|---|---|---|---|
| dispersion | ΔGVD | Dispersion mismatch (fs²) | 0 | 200 |
| reference_delay | Δz_r | Reference delay error (μm) | 0 | 5.0 |
| spectral_roll_off | ΔR | Spectral roll-off error (dB/mm) | 0 | 1.0 |
Reconstruction Triad Diagnostics
The three diagnostic gates (G1, G2, G3) characterize how reconstruction quality degrades under different error sources. Each bar shows the relative attribution.
Model: low coherence interferometry — Mismatch modes: dispersion mismatch, motion artifact, sensitivity rolloff, mirror artifact
Noise: speckle — Typical SNR: 15.0–40.0 dB
Requires: wavelength axis, dispersion coefficients, reference delay, sensitivity roll off
Modality Deep Dive
Principle
Optical Coherence Tomography uses low-coherence interferometry to produce cross-sectional images of tissue microstructure. A broadband light source (superluminescent diode, ~840 nm or ~1310 nm) is split between sample and reference arms. Interference occurs only when the path lengths match within the coherence length (~5-10 μm), providing axial resolution. Spectral-domain OCT records the spectral interferogram and uses FFT for fast depth-resolved imaging.
How to Build the System
Build or acquire a spectral-domain OCT system: broadband SLD source (center 840 nm, 50 nm bandwidth for retinal; 1310 nm for dermal/cardiac), fiber-based Michelson interferometer, galvo scanner for lateral scanning, and a spectrometer with line camera (2048-4096 pixels) for spectral detection. Calibrate wavelength-to-wavenumber mapping, dispersion compensation, and reference arm delay. For swept-source OCT, use a frequency-swept laser (100-400 kHz sweep rate) and balanced detector.
Common Reconstruction Algorithms
- FFT-based spectral-domain OCT reconstruction (spectral interferogram → A-scan)
- Dispersion compensation (numerical or hardware)
- Speckle reduction (spatial/angular compounding, or deep-learning)
- Segmentation of retinal layers (graph-based, U-Net, or transformer models)
- OCT Angiography (OCTA) via decorrelation or phase-variance of repeated B-scans
Common Mistakes
- Dispersion mismatch between sample and reference arms degrading axial resolution
- Mirror image artifact from complex conjugate ambiguity in SD-OCT
- Sensitivity roll-off at deeper imaging depths not compensated
- Motion artifacts in 3-D OCT volumes (eye motion for ophthalmic OCT)
- Incorrect refractive index assumption for depth scale calibration
How to Avoid Mistakes
- Match fiber lengths and add numerical dispersion compensation in reconstruction
- Place the zero-delay near the sample surface; use full-range OCT if needed
- Use swept-source OCT for reduced roll-off; optimize spectrometer for uniform sensitivity
- Apply eye-tracking or motion-correction algorithms; average repeated B-scans
- Calibrate depth scale with a known-thickness reference standard
Forward-Model Mismatch Cases
- The widefield fallback applies spatial blur, but OCT acquires spectral interferograms that encode depth via low-coherence interferometry — the interference fringe pattern bears no resemblance to a blurred image
- OCT depth resolution comes from the broadband source coherence length (~5-10 um), not from spatial PSF — the widefield operator cannot model the axial sectioning, dispersion, or spectral-to-depth FFT relationship
How to Correct the Mismatch
- Use the OCT operator that models spectral-domain interferometry: y(k) = |E_ref + E_sample(k)|^2, where depth information is encoded in the spectral fringe frequency
- Reconstruct A-scans via FFT of the spectral interferogram after dispersion compensation and k-linearization; B-scans are formed by lateral scanning
Experimental Setup
Heidelberg Spectralis HRA+OCT / Zeiss Cirrus HD-OCT 5000
840
45
5
15
40
6.0
512
512
98
Signal Chain Diagram
Key References
- Huang et al., 'Optical coherence tomography', Science 254, 1178 (1991)
- de Boer et al., 'Twenty-five years of OCT', Biomed. Opt. Express 8, 3248 (2017)
Canonical Datasets
- Duke SD-OCT DME dataset (Chiu et al.)
- RETOUCH Challenge (retinal OCT)
- OCTA-500 (Li et al., Scientific Data 2024)