Abstract
OCT (Optical Coherence Tomography) imaging system is a kind of medical imaging system that is mainly applied in surface detection, with the main advantage of no side effects on the human body. OCT system can be roughly divided into TD(Time Domain) and FD(Frequency Domain). Using the FD-OCT system, the proposed system architecture consists of Re-sampling unit, Hamming window unit, Fourier and inverse Fourier transform unit, and Log unit. The Re-sampling unit applies the calibration parameters to do the re-sampling; the hamming window unit reduces the high frequency noise from un-continuous data; the Fourier and inverse Fourier transform unit use the SDF (single-path delay feedback)-Pipeline architecture, which is a lower-cost hardware architecture, CSD(Canonic Signed Digit) constant multiplier and CORDIC to save the cost and disassembles DFT by Radix-2^3 and Radix-2^4 algorithms; and Image Processing Log computes the natural logarithm base and Taylor expansion. To support the main phase of the calibration function obtained, the CORDIC circuit is applied to obtain the phase. In order to save design costs, the CORDIC multiplier and the phase obtaining circuit are shared. In addition, since the phase obtained method needs the Fourier transform and the inverse Fourier transform operations, the control circuit is applied for reusing the Fourier transform hardware, for sharing the original memory RAM to reorder data out, and to wait until the previous operation is completed. The shared CORDIC circuit saves 5.68% of the hardware in gate counts. After circuit synthesis and Automatic Place and Route, the operating frequency can be operated at 80MHz, and the use of system hardware area is 503.7K gate counts.