Dual window method for processing spectroscopic optical coherence tomography signals with high spectral and spatial resolution

The generation of spectroscopic optical coherence tomography (SOCT) signals suffers from an inherent trade off between spatial and spectral resolution. Here, we present a dual window (DW) method that uses two Gaussian windows to simultaneously obtain high spectral and spatial resolution. We show that the DW method probes the Winger time-frequency distribution (TFD) with two orthogonal windows set by the standard deviation of the Gaussian windows used for processing. We also show that in the limit of an infinitesimally narrow window, combined with a large window, this method is equivalent to the Kirkwood & Richaczek TFD and, if the real part is taken, it is equivalent to the Margenau & Hill (MH) TFD. We demonstrate the effectiveness of the method by simulating a signal with four components separated in depth or center frequency. Six TFD are compared: the ideal, the Wigner, the MH, narrow window short time Fourier transform (STFT), wide window STFT, and the DW. The results show that the DW method contains features of the Wigner TFD, and that it contains the highest spatial and spectral resolution that is free of artifacts. This method can enable powerful applications, including accurate acquisition of the spectral information for cancer diagnosis.