Advances in optical coherence tomography (OCT) rely on the availability of broadband light that is spatially coherent. We present a technique to characterize coherence properties of broadband light using optical phasespace contours in transverse momentum and position. We demonstrate that these contour plots can be directly measured by a simple heterodyne imaging scheme possessing high dynamic range (130 dB) and 0.1 fW sensitivity (for mW input beams). These phase space distributions are shown

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... yield quantitative information on the longitudinal and transverse coherence and the wavefront curvature of the light beam. We apply this technique to characterize the light emitted by a novel high-power extended-bandwidth superluminescent diode (SLD) recently developed at the David Sarnoff Research Center. Its performance is compared to that of standard commercially available SLDs.