Optimization for Axial Resolution, Depth Range, and Sensitivity of Spectral Domain Optical Coherence Tomography at 1.3 μm

Sang-Won Lee, Hyun-Woo Jeong, Yeh-Chan Ahn, Woonggyu Jung, Zhongping Chen and Beop-Min Kim

J. Korean Phys.Soc. 55,2354 [doi: 10.3938/jkps.55.2354 | PDF Download]

We have developed high-speed and high-resolution spectral domainoptical coherence tomography at 1.3 $\mu$m using an InGaAs line-scancamera and a broadband light source with the bandwidth of 170 nmthat produces a theoretical axial resolution of 4.4 $\mu$m in air.We compared axial resolutions from point spread functions (PSFs) anddepth ranges while changing the full spectral bandwidth detected bythe camera and describing the optimization process for the axialresolution, the depth range, and the sensitivity for SD-OCT system.We found that SD-OCT at 1.3 $\mu$m cannot satisfy the conditionsboth below the axial resolution of 5 $\mu$m and above the depthrange of 2 mm because of the restricted pixel number of theline-scan camera. To scan a large depth range, the axial resolutionhas to be sacrificed. In addition, the sensitivity rolls off slowlyas a function of the depth if a large depth range is scanned. On theother hand, if the axial resolution needs to be close to thetheoretical one, the depth range becomes limited and the sensitivitydecays quickly. Since we have to maintain a reasonable depth rangeof 2.0 mm, we chose the spectrum full bandwidth of 214 nm capturedby the detector to balance the axial resolution of 8.2 $\mu$m. Inthis setting, the sensitivity of our OCT system was measured at107.1 dB. Theoretical and experimental results are compared andpresented in this paper.