Photoacoustic Imaging Based On Michelson Interferometer

Photoacoustic imaging has been extensively studied due to the advantages of high resolution,deeper imaging depth,ability to perform functional imaging and nonionizing radiation.Photoacoustic imaging based on Michelson interferometer with large bandwidth,high resolution and other merits,becomes a hot spot for people to study.In this paper,based on the study of phantom's absorption and scattering characteristics,we fabricated phantom that can simulate human muscle.Using photoacoustic imaging system that constructed by ourselves to detect photoacoustic signal,the effects of system parameters and sample parameters on photoacoustic signal and imaging are investigated quantitatively.Finally,we explore the detection of photoacoustic signal by surface array detection CCD.The phantom that can simulate human muscle was fabricated by ourselves,and the characteristics of absorption and scattering about the phantom were studied.The contents of the absorbing substances and the scattering substances in the phantom were determined,so that the optical properties of the phantom were consistent with that of the human muscle tissue.It was found that at the fixed wavelength of 532 nm,the absorption coefficient and the reduced scattering coefficient of the phantom increase with the increase of the content of the absorbing substance and the scattering material in the sample.According to this quantitative dependency relationship,any phantom of different optical properties can be successfully prepared.In order to obtain the photoacoustic pressure distribution inside the phantom.The photoacoustic imaging system based on acoustic detection was constructed and the photoacoustic signal was detected.And the imaging of phantom was realized using this system,getting the photoacoustic pressure distribution inside the phantom,besides the imaging bandwidth and axial resolution of the system were given.The effect of the concentration and depth of chromophore on the distribution of photoacoustic pressure inside the phantom was studied.The experimental results show that the concentration and depth of the chromosomes can affect the intensity of the photoacoustic signal and signal to noise ratio of the photoacoustic pressure,besides the concentration of the chromosomes can affect the range of photoacoustic pressure distribution.Using the Michelson interferometer to detect the photoacoustic signals,photoacoustic imaging system based on Michelson interferometer was constructed.According to the obtained signals,the imaging bandwidth and resolution of the system were achieved.and the system was further optimized through changing the parameters of its elements.The experimental results show that the sensitivity of the photoacoustic imaging system based on Michelson interferometer are much better than those of the photoacoustic imaging system based on acoustic detection.and the pump light intensity,the probe light intensity is positively correlated with the photoacoustic signal intensity and SNR.Furthermore,the photoacoustic signal was detected by CCD surface array imaging device using non-focused Michelson interference configuration,effective information for area-array photoacoustic signal was obtained preliminarily.