All-Fiber Multifunctional Swept Source Polarization Sensitive OCT

Abstract

 

Purpose

 

Many ophthalmic diseases are associated with changes in tissue birefringence or vasculature. Polarization sensitive OCT (PS-OCT) can assess depth-resolved tissue birefringence in addition to structure. However, most existing PS-OCT systems are complex and employ bulk optics which are susceptible to misalignment, making clinical translation difficult. OCT angiography visualizes vasculature by performing repeated B-scans to generate contrast from blood flow. We demonstrate an all-fiber PS-OCT system which is robust, simple to align, and can perform integrated structural, polarization and angiographic imaging.

 

Methods

 

The PS-OCT system uses a polarization maintaining fiber to multiplex two orthogonal polarization states of light illuminating the sample with different delays. The system operates at 100 kHz axial scan rate and 1050 nm wavelength. For polarization sensitive detection, two fiber based polarization beam splitters (FPBS) are used. Polarization controllers are employed to manage the FPBS detection, removing polarization ambiguity. Once calibrated, the system requires no further alignment and can be easily maintained. Uncertainties of the input light polarization states and the influence of cornea birefringence are automatically corrected in data processing.

 

Results

 

Fig. 1 shows a representative wide-field 9mm×6mm birefringence image of the left eye in a healthy subject using the all-fiber PS-OCT system. Fig. 2 shows a simultaneously acquired polarization and angiography image over the optic nerve head (3mm×3mm) of the right eye in a healthy subject.

 

Conclusions

 

The all-fiber PS-OCT can provide structural, polarization and angiography of human eyes in a single system. Since the system does not employ bulk optics components to handle polarization, it greatly simplifies system design and maintenance, and has improved sensitivity. This system has the potential to make PS-OCT more accessible for clinical studies while enabling integrated structural and angiographic imaging.

 

 

Figure 1. Wide field OCT imaging of the left eye in a healthy subject (9mm×6mm, 1000×200 A-lines). (A) Fundus view. (B) Cross-sectional B-scan image. (C) Corresponding phase retardation image.

 

 

Figure 2. Multifunctional imaging of optic nerve head of the right eye in a healthy subject (3mm×3mm, 300×300×5 A-lines, 5 repeated B-scans). (A) Fundus view. (B) Angiography. (C) Cross-sectional image. (D) Corresponding phase retardation image.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 551 imaging/image analysis: non-clinical