This article by R. Leitgeb, C. K. Hitzenberger, and A. F. Fercher from the University of Vienna discusses the performance and noise sources in Fourier Domain Optical Coherence Tomography (FDOCT) setups compared to Time Domain Optical Coherence Tomography (TDOCT). The authors compare the sensitivity of FDOCT systems, which can achieve sensitivities well above 80dB even in low light levels and high-speed detection, to current standard TDOCT systems. They detail the measurement of sensitivity in FDOCT, confirm theoretical values, and explain how the Fourier transformation process affects noise levels. The study highlights that FDOCT systems have a significant sensitivity advantage over TDOCT, making them particularly suitable for low-light and high-speed imaging applications. The authors also address challenges such as phase fluctuations and coherent noise, suggesting methods to mitigate these issues. Overall, the article provides a comprehensive analysis of the advantages and limitations of FDOCT in various medical imaging scenarios.This article by R. Leitgeb, C. K. Hitzenberger, and A. F. Fercher from the University of Vienna discusses the performance and noise sources in Fourier Domain Optical Coherence Tomography (FDOCT) setups compared to Time Domain Optical Coherence Tomography (TDOCT). The authors compare the sensitivity of FDOCT systems, which can achieve sensitivities well above 80dB even in low light levels and high-speed detection, to current standard TDOCT systems. They detail the measurement of sensitivity in FDOCT, confirm theoretical values, and explain how the Fourier transformation process affects noise levels. The study highlights that FDOCT systems have a significant sensitivity advantage over TDOCT, making them particularly suitable for low-light and high-speed imaging applications. The authors also address challenges such as phase fluctuations and coherent noise, suggesting methods to mitigate these issues. Overall, the article provides a comprehensive analysis of the advantages and limitations of FDOCT in various medical imaging scenarios.