Efficient Signal Processing Algorithm for Fast Optical Doppler Tomography Systems

Optical Doppler tomography (ODT) is an imaging technique which uses the Doppler shift observed in the spectrum of the backscattered light to form images of blood flow in a sample tissue. As data acquisition rates for ODT systems become greater, the need arises for a fast algorithm able to deal with increasingly short time records of the backscattered light. The objective of this paper is to present a potentially real-time algorithm that is an accurate estimate of the flow vector and is robust to noise. Our contribution is that we transform the physical model of the data, stemming from the nature of ODT, into an AM-FM model. The proposed estimator, rooted in the AM-FM model, finds the Doppler shift from a phase shift. The phase shift is caused by the Doppler shift in a small time interval between the recording of the signal and its later version. The calculated Doppler shift is used to form the image of the blood flow in the tissue.