1 Department of Photonics Engineering, Technical University of Denmark2 Diode Lasers and LED Systems, Department of Photonics Engineering, Technical University of Denmark3 Medical University of Vienna4 Risø National Laboratory for Sustainable Energy, Technical University of Denmark5 Ludwig-Maximilians-University Munich6 Copenhagen Center for Health Technology, Center, Technical University of Denmark
We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers show different polarization characteristics in the eye, such as depolarization in the retinal pigment epithelium and birefringence in retinal nerve fiber layer and sclera. The increased speed allows imaging of large volumes with reduced motion artifacts. Moreover, averaging several two-dimensional frames allows the generation of high-definition B-scans without the use of an eye-tracking system. The increased penetration depth of the system, which is caused by the longer probing beam wavelength, is beneficial for imaging choroidal and scleral structures and allows automated segmentation of these layers based on their polarization characteristics.
Journal of Biomedical Optics, 2013, Vol 18, Issue 2