Abstract
Purpose :
Polarization related image artifacts are often observed in optical coherence tomography (OCT) data. When a polarized light source is used, only sample light components polarized parallel to the reference beam’s polarization state can be observed. Here we propose a simple hardware modification to induce a continuum of different polarization states in the reference beam in order to be sensitive to any sample light polarization and thereby reduce image artifacts in OCT data.
Methods :
A spectral domain OCT system was used to demonstrate polarization-insensitive OCT imaging in ocular tissue. The system employed a superluminescence diode (SLD) light source centered at 840 nm with a bandwidth of 50 nm. The interferometer was implemented in a fiber-based Michelson type layout. A depolarization stage based on liquid crystal depolarizers was induced in the reference arm of the interferometer in order to pseudo-depolarize the reference beam. OCT imaging at an A-line rate of 20 kHz was performed in the sclera of post-mortem, formalin-fixed bovine eyes, both with and without the depolarization stage.
Results :
OCT images obtained in the standard OCT configuration – i.e. without depolarization stage in the reference arm of the OCT interferometer – reveal typical hypointense artifacts in scleral tissue owing to the strong birefringence produced by the collagenous structures (see Figure 1Α). Conversely, OCT imaging with the depolarization stage drastically reduces these artefacts, thereby revealing a more complete picture of the tissue morphology (see Figure 1Β).
Conclusions :
Polarization-insensitive OCT imaging based on a simple and inexpensive modification of the standard hardware layout was presented. The performance of this easily implemented method was compared to a conventional OCT approach and revealed improved OCT imaging with reduced polarization artefacts. Polarization-insensitive OCT based on pseudo-depolarized reference light may enable superior image quality, without the need to sacrifice imaging speed or ranging depth.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.