Fig. 1. Comparison between standard axial scanning mode (left) and standard transverse scanning mode (right)^[2]

Fig. 2. Illustration of signal retrieval in en-face FD-OCT

Fig. 3. Time-domain OCMs using different structures^[3]. (a) Stretched PZT; (b) stacked PZT

Fig. 4. Full-field OCT system based on phase shifting in time-domain^[20]

Fig. 5. Full-field OCT system based on single-shot exposure^[24]

Fig. 6. Amplitude and phase reconstruction of one-dimensional signal based on Hilbert transform in spatial-domain

Fig. 7. Schematic of off-axis TD-FFOCT based on digital holography^[26]

Fig. 8. Image processing of off-axis TD-FFOCT system based on digital holography^[25]. (a) Interference pattern in spatial-domain; (b) frequency spectrum of interference pattern; (c) en-face image reconstructed from +1 order spectrum; (d) 3D tomographic structure recoveredby image stitching

Fig. 9. Schematic of off-axis TD-FFOCT based on photorefractive hologram material^[27]

Fig. 10. Signal reconstruction of off-axis TD-FFOCT based on photorefractive hologram material^[14]

Fig. 11. Schematic of line-scanning FD-OCT system^[34]. (a) Optical path of line-scanning FD-OCT system; (b) signal recording process

Fig. 12. FF-SS-OCT system. (a) Schematic of on-axis FF-SS-OCT^[39]; (b) schematic of off-axis FF-SS-OCT^[40]

Fig. 13. Schematic of focused Gaussian beam through objective lens with different NA

Fig. 14. Angular spectrum method and holoscopy. (a)Angular spectrum method based on plane wave decomposition; (b) holoscopy^[41]