Research On Control System Based On Swept Source Optical Coherence Tomography

Optical Coherence Tomography(OCT)technology can perform high-resolution real-time imaging of biological tissues.With its non-destructive,high resolution,fast imaging speed,and relatively low manufacturing cost,it has broad clinical application prospects,Based on the endoscopic sweep source frequency OCT(SS-OCT)technology,it has important application value in the early tumor detection of the digestive tract.The endoscopic SS-OCT system is of great significance due to its high detection sensitivity,fast imaging speed,and the ability to perform rotating scanning imaging of the digestive tract,which is beneficial to the preoperative and postoperative condition detection of clinical treatment.This paper studies the control system of swept-frequency endoscopic optical coherence tomography.The main contents are as follows:(1)The hardware part and optical path part of the endoscopic SS-OCT system are designed.The hardware part mainly includes high-speed acquisition card,brushless DC motor,and stepper motor.The maximum acquisition speed of the acquisition card can reach 4GS/s,the maximum speed of the brushless DC motor is 12000 rpm,the stepping accuracy of the stepping motor is 1um,the center wavelength is 1310 nm,the sweep frequency is 200 k Hz,and it is based on the principle of Michelson interferometer The optical path of the OCT system is designed.(2)Using FPGA board to design the system logic control sequence,suppress the image shift phenomenon of OCT system.Synchronous control of stepper motor movement,brushless DC motor movement,swept frequency light source triggering,and capture card acquisition is carried out to align the starting point of each frame of image,and force a fixed image size to be output,which suppresses the deviation of the image.(3)Use FPGA+GPU to perform data processing on the endoscopic SS-OCT system.Use FPGA to perform zero-filling,windowing,FFT,logarithmic processing for each piece of collected A-Scan data,and use GPU for secondary acceleration of the processed data,including normalization and polar coordinate conversion And image reconstruction,the final result is transmitted to the computer for display,when the image size is 1000×1000,real-time image display of 200 frames per second can be achieved.(4)A set of endoscopic SS-OCT system based on Lab VIEW was built.The axial resolution of the system was 9.24 um,the imaging depth was 4.46 mm,and the sensitivity was always above 100 d B within the imaging depth range.The tape alignment was completed by this system,Fingers,and mouse esophagus imaging experiments.