A Miniaturized Pre-calibration Based Lissajous Scanning Fiber Probe For High Speed Endoscopic Optical Coherence Tomography

Optical coherence tomography(OCT)technology is a high-resolution,non-invasive,non-radiation optical imaging technology.The combination with the fiber-optic endoscope probe makes up for its shallow penetration depth and has broad prospects in medical endoscopic imaging.This article firstly introduces the technical overview of the OCT and application of endoscopic probes.Secondly,the basic theory of swept-source OCT(SSOCT)system is introduced,including the imaging principle,the performance parameters and the structure of SSOCT system.The advantages of the SSOCT system are described.Then the selection rules of the frequencies for high frame rate and high resolution of Lissajous scan are described.And the selection rules for SSOCT system have been discussed.The key factors affecting the Lissajous scan and the evaluation of the frame rate and fill rate of the Lissajous scan are introduced.A new simulation method applied to the Lissajous scan of the SSOCT system was proposed to calculate the relationship between the total lobe number,fill rate,and frame rate of Lissajous scan.Next,the design of a miniaturized forward-viewing endoscopic probe is explained.The structural components of the probe are introduced firstly.The ABCD matrix method is used to select the model of the GRIN lens and the appropriate air gap distance.The GRIN lens and the air gap distance meet the requirements of the forward-viewing endoscopic probe.Then the structure of the asymmetric optical fiber cantilever is introduced.The resonant frequencies of the asymmetric optical fiber cantilever are simulated by using COMSOL software.The correctness of the simulation results is verified by experiments.The parameters of the cantilever structure whose biaxial scanning frequencies can reach the designed frequencies were determined.Finally,the manufacturing process of the probe is explained.Ultimately,the image reconstruction experiments were performed with the fabricated probe.The pre-calibration of Lissajous scanning trajectory applied to the probe was proposed.The stability and repeatability of the Lissajous scanning trajectory of the probe is proven.Finally,the assembled endoscopic probe was used for OCT endoscopic imaging.