Optimization And Application Of Polarization-sensitive OCT For Sweep Source

Optical coherence tomography(OCT)is a new interferometric technique.It mainly measures the intensity of light reflected from the interior of the tissue,so as to achieve noninvasive high-resolution cross-section imaging.This non-contact imaging method has a wide application prospect in medicine.But the traditional OCT technology is unable to detect some less obvious features,so the traditional OCT technology has been extended to develop some new OCT measurement technology.Polarization sensitive optical coherence tomography(PS-OCT)is an extended OCT technology.It mainly detects the change of polarization state of polarized light inside the tissue,so as to determine the polarization characteristics inside the tissue.These characteristics include birefringence,birefringence and optical axis.This provides additional contrast for the image.Most biological tissues have birefringence polarization characteristics,so PS-OCT is an effective way to measure birefringence.This paper focuses on the optimization of an imperfect PS-OCT system.The optimized system is tested.The Jones matrix is used to calculate the polarization characteristics in the later stage of the system,so the dual channel acquisition is inevitable.However,the original system has not designed a supporting synchronous control system,which makes the dual channel data can not be collected at the same time,resulting in the two channel images inevitably flutter.This will bring errors to the later calculation of polarization characteristics.Therefore,this paper designs the corresponding synchronization control system according to the characteristics of the optical system.Using the synchronous clock signal of the scanning light source,the synchronous operation of each module of the control system is controlled,including the coordination and synchronization of the acquisition module and the galvanometer control module,so that the acquisition cycle of a group of data is consistent with the cycle of the galvanometer rotating back and forth.And the two channels are collected at the same time to ensure the data consistency of the two channels,so as to improve the reliability of the data.At the same time,the original system does not realize the function of real-time display of dual channel data,which makes it impossible to judge the quality of the collected data according to the real-time image,and adjust the optical path according to the real-time image.Therefore,according to the synchronous control system to complete the preparation of supporting software.It includes the compilation of system interface,so as to realize the function of human-computer interaction.Then,we use multithreading technology to process the program of each module,including data acquisition,data processing and data display module.The synchronous operation of each module is realized by using synchronous lock.Finally,a data storage scheme using ring buffer is designed to realize the real-time imaging of dual channel system.Finally,the optimized system is used to test the optical components such as flat mirror,infrared card,glass slide,skin and biological tissue.The experimental results also verify the feasibility of the system.And the phase delay of the glass slide is measured,and compared with the results before optimization,the phase measurement accuracy of the system is significantly improved.