Optical coherence tomography

Abstract

The review provides a concise explanation of principles of operation of different optical coherence tomography methods. A comparative analysis of their advantages and disadvantages is presented in relation to specific applications. The review will assist the reader in making an educated choice on the most suitable optical coherence tomography method to be used in a particular application.

Fig. 1

Cross-section image of the retina using an en face time domain OCT system driven by a large bandwidth source (Cucu et al., 2006). Lateral size: 7.5 mm, vertical size is along depth, 0.725 mm measured in the retina. ILM, inner limiting membrane; NFL, nerve fibre layer; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; ONL, outer nuclear layer; ELM, external limiting membrane; IS/OS, junction between the inner and outer photoreceptors; RPE, retinal pigment epithelium; CC, choriocapillaris; C, choroid.

Fig. 2

TD-OCT setup.

Fig. 3

TD-OCT: Relative size of the coherence length, cl, required depth resolution δz, and OPD axial range 2Δz determined by the axial extension of the Object to be investigated. For simplicity, the index of refraction is considered as 1.

Fig. 4

SB-OCT setup.

Fig. 5

SS-OCT setup.

Fig. 6

(a) Spectrum output of the interferometer for two OPD values, left: ∼3 cl, right: ∼6 cl; (b) SD-OCT sampling function, of width δλ, spectrum is read in a time T either by downloading the charge from the linear camera array, or by tuning the frequency of the SS, the large arrow suggests that by doing so, the spectrum shown above in (a) is transferred to the output signal shown in (c) below; (c) signal delivered by the Processing unit in Figures 4 and 5.

Fig. 7

SD-OCT: Relative size of the CL extension of interfering wavetrains, required depth resolution δz, and axial range Δz determined by the axial extension of the Object to be investigated.