Computational defocus correction in spatial frequency domain imaging

In spatial frequency domain imaging (SFDI), tissue optical properties are estimated by projecting spatial frequencies on the tissue and measuring back-scattered reflectance. We characterize the measurement error in camera-defocused SFDI and evaluate 1) dividing the defocus response and 2) cubic phase mask approaches in recovering SFDI performance. Cameradefocused SFDI underestimates tissue optical properties and loses spatial resolution. Both methods are shown to double the object distance range over which optical property measurements are within 25% of best focus values, though spatial resolution is lost. This work extends SFDI’s potential applications to remotely monitoring cardiovascular health in clinics and homes.