Real-time phase resolved optical coherence tomography and optical Doppler tomography using optical Hilbert Transformation

Yonghua Zhao,Hongwu Ren,Zhihua Ding,Zhongping Chen,Woong G Jung,Jianjun Miao,J Stuart Nelson

doi:10.1117/12.470472

Abstract

We have developed a novel optical Hilbert transformation for phase-resolved optical Doppler tomographic imaging. Using a resonant scanner in the reference arm of the interferometer and the axial scanning speed of 4 kHz, the frame rate can be as high as 10 Hz for both structural and Doppler blood flow imaging 400 axial scans. The system has high sensitivity for measuring the Doppler frequency shift due to moving red blood cells. Real time images of in vivo blood flow in human skin using this interferometer are presented.

Highlights

Optical coherence tomography (OCT) [1] is a noninvasive, noncontact imaging modality that uses coherent gating to obtain high-resolution cross-sectional imaging of tissue microstructure
Optical Doppler tomography (ODT), for example, combines Doppler principle with coherence gating for tomographic imaging of tissue structure and blood flow, simultaneously [2,3,4,5,6,7]
We describe in detail a technique to overcome the aforementioned limitations by incorporating an optical Hilbert transformation into our phase-resolved OCT/ODT system

Summary

Introduction

Optical coherence tomography (OCT) [1] is a noninvasive, noncontact imaging modality that uses coherent gating to obtain high-resolution cross-sectional imaging of tissue microstructure. Phase-resolved OCT/ODT [6,7,10,11] uses the phase change between the measured interference signals from sequential axial scans for velocity image reconstruction. We describe in detail a technique to overcome the aforementioned limitations by incorporating an optical Hilbert transformation into our phase-resolved OCT/ODT system This approach combines circularly polarized reference and linearly polarized sample signals, which introduces a 90 degree phase shift in the interference signal. The real and imaginary parts of the interference field are produced in two output channels based on polarization discrimination This method generates analytical continuation optically and does not have the restriction on phase modulation frequency. Using a high-speed RSOD based on a resonant scanner in combination with the proposed optical Hilbert transformation technique, real-time simultaneous images of tissue structure and blood flow velocity can be obtained

Theory

Methods

Results

Conclusions