FPGA-based non-uniform fast Fourier transform (NUFFT) algorithm for real-time OCT signal processing

We developed an FPGA-based engine for Fourier-domain OCT that performs real-time signal processing based on Non- Uniform Fast Fourier Transform (NUFFT). The basic NUFFT algorithm is discussed and compared with cubic-spline interpolation regarding efficient re-sampling in k-space with different phase nonlinearities of sinusoidal swept sources. The NUFFT algorithm was adapted for an implementation in an FPGA and its accuracy is analyzed and assessed using simulated numerical data. When implemented, the NUFFT algorithm allows a processing performance at a sampling rate of 100 MS/s. The real-time processing capability was tested with sinusoidal bi-directional swept sources with A-scan rates of 50 kHz.