Research On Optical Fiber Compound Detection Technology Based On Swept Source Optical Coherence Tomography

Optical Coherence Tomography(OCT)is an important cross-sectional imaging modality for biomedical and clinical applications.Swept source OCT(SS-OCT)is one of the OCT technology,which has been developed from the spectral domain OCT(SD-OCT).To be specific,the SS-OCT does not require the line scan camera and spectrometer such that it possesses faster imaging speed,better sensitivity with imaging depth,longer imaging range and higher detection efficiency.It would improve the resolution,depth and sensitivity of imaging,and promote the development of OCT technology in biomedical field.Moreover,the OCT technology becomes possible in the application of vivo imaging because of the biomedical probes.This dissertation focuses on the key technologies of the compound detection system based on the SS-OCT.The main researches of this paper are summarized as follows:(1)Based on the existing research results of OCT technology and the theory of SS-OCT,the whole system is designed.Firstly,we analyze the principle and characteristics of the system.Then,the all-fiber SS-OCT system is built with the use of the home-made swept source.The centre wavelength is 1300 nm,the bandwidth is 70 nm,the sweep rate is 2 kHz,and the output power is 5.4 mW.The performance index of the system is the resolution in the air with the magnitude of 10.6 ?m,the imaging depth of 1.58 mm,and the sensitivity of 85 dB.Finally,the imaging experiments of the stacked glass is carried out.(2)The influence of the swept source on imaging quality in SS-OCT system is studied and proposed that this novel swept sources is fabricated by using cascade QW-SOA and QD-SOA.By comparing different cascading methods,it is concluded that the parallel QW-SOA and QD-SOA are the most effective way to spread the range of the swept source.Thus,the imaging resolution and depth of SS-OCT system are improved.This method further improves the performance of the swept source and provides a reference for the clinical imaging monitoring of SS-OCT technology in vivo.(3)In the cascaded configuration,the dispersion attenuation of the system is studied.The coupling method,which is using the wavelength division multiplexing plus delay line,is proposed to solve the problem.The coupling mode of wavelength division multiplexing can minimize the influence of dispersion attenuation caused by QW-SOA and QD-SOA in different bands,and the delay line can improve to detect the signal effectively.The comparison of multilayer glass slides shows that this method can improve the performance of swept source based on cascaded SOAs,and has a positive effect on improving the imaging quality of SS-OCT.The traditional SS-OCT technique has a single detection function.The SS-OCT complex probe technique which is suitable for clinical diagnosis and treatment in vivo is proposed.This paper not only details the working principle and basic structure of the complex probe,but also designs the development and encapsulation method of the complex probe.Based on three-core optical fiber and fiber bragg grating,the complex probe has high efficiency,real time,high sensitivity to detect the curvature in real time,temperature,blood concentration and pulse vessel beating in vivo.It is widely used in SS-OCT endoscope or vascular monitoring imaging system.(4)Two kinds of probes were developed by welding the core of the three-core fiber and the core of the central axis with the single-mode fiber,respectively.The theoretical analysis of these two kinds of probes with different core deviation is carried out,as well as the comparative experimental study on sensing properties of curvature,temperature,refractive index and pulse.The experimental results show that the bending sensitivity of the split-core fiber and single-mode fiber fusion probe using the three-core fiber is 4 times higher than that of the central fiber core and single-mode fiber fusion probe,which provides a reference for the development of the high-sensitivity bend probe.(5)The application of the complex probe in the compound detection system based on SS-OCT is studied.The complete structure of the system is designed and built.The method of using Faraday rotation mirror to enhance the detection arm is proposed.This method finally realizes the real-time and accurate clinical application of multi-parameter SS-OCT based on complex probe.