Fig. 1.

(A) Fiber-based visible light spectral / Fourier domain OCT system for imaging the human retina (M: mirror, SPF: short pass filter, LPF: long pass filter, AL: achromatizing lens, RC: reflective collimator, L: lens, FL: focusing lens, DG: diffraction grating, LSC: line-scan camera, NDF: neutral density filter, DM: dichroic mirror). (B) Zero-power triplet achromatizing lens (AL) used in the sample arm. (C) Source spectrum measured by the spectrometer. (D) Zemax simulation of the focal shift at the retina for a model eye [27] over a broad design bandwidth (450-650 nm). With the AL designed to achromatize the entire sample arm, including the eye (blue line), the focal shift is much smaller than the diffraction limited range (dotted horizontal lines). The root-mean-squared defocuses are provided in the legend. (E) Zemax simulation of the spectrometer chromatic focal shift over the same bandwidth (450-650 nm). The overall focal shift (solid red line) versus angle (θ) is fit by a line approximating the line scan camera (dotted red line). The residual defocus (solid black line) is much smaller than the diffraction limited range (dotted horizontal lines). (F) The sensitivity rolloff of the system with depth (in air), both with and without dispersion compensation (DC) is shown. Note that the measured rolloff approaches the rolloff set by the interference envelope (circles). (G) The Fourier transform of the spectrum represents the point spread function achieved at or near zero delay. (H) Similar to the rolloff, the measured axial resolution approaches that set by the interference envelope, indicating correct resampling and dispersion compensation.