Research On Birefringence Demodulation And Depolarization Based On Polar Decomposition In Catheter-based PS-OCT

Catheter-based polarization sensitive optical coherence tomography(PS-OCT)can provide information of tissue birefringence and depolarization,providing more basis for tissue characteristics identification.Can provide information on the composition of coronary atherosclerotic plaques at a higher level than intensity based OCT.But catheter-based PS-OCT study has many challenges,at the time of catheter probe at high speed,fiber optic catheter is under extrusion,twisted,external force disturbance such as rotation,the bearing of the optical signal will be a drop in signalto-noise ratio,polarization instability,phase change and noise leads to the phenomenon such as partial elimination,the serious influence our concern birefringence phase delay imaging effect.The analysis and elimination methods of noise-induced depolarization in catheter-based PS-OCT have not been reported in relevant literature.The traditional Jones matrix demodulation method cannot demodulate the depolarization information,but the Mueller matrix after incoherent averaging carries the depolarization information.Based on this,we carried out the birefringence solution and depolarization effect of catheter-based PS-OCT.Major works completed include:1.Dual-State of polarization catheter-based PS-OCT system of deeply-multiplexing for endovascular imaging was constructed in this paper.The Jones matrix diagonalization method(JMD)and the similar Muller matrix method(SMM)are compared.The incoherent average algorithm and muller matrix polarization decomposition method are analyzed.The mechanism of tissue depolarization and noise-induced depolarization is studied.A method based on Mueller matrix incoherent averaging and polarization decomposition is proposed to eliminate the influence of depolarization effect on birefringence measurement.2.A Monte Carlo simulation method based on PS-OCT is proposed to describe the birefringence and depolarization effect numerically.The path model of photon propagation is described,the transmission rules of polarization information during photon propagation,the monte Carlo simulation steps of photon collection and photon interference in PS-OCT system are constructed.The reliability of PS-OCT Monte Carlo simulation imaging model is verified by simulation of tissue depolarization.3.A series of Monte Carlo simulations and catheter-based PS-OCT experiments are used to verify the noise-induced depolarization effect and its effect on birefringence measurement of various in vitro biological tissues,including pig myocardium,pig cardiovascular,fingernail,chicken,etc.It is also verified that SMM incoherent averaging and polarization decomposition have better effect on eliminating the influence of depolarization than JMD coherent average and eigenvalue decomposition.In the simulations,the peak signal to noise ratio(SNR)of SMM is 8.9 d B higher than that of JMD.In the experiment,SMM has higher contrast than JMD in the strong depolarization region.