Research On Key Technologies Of Fast Swept Source

Optical Coherence Tomography(OCT)is a new non-destructive,non-invasive optical imaging technology.OCT technology has developed from the earliest Time-Domain OCT(TD-OCT)to the current Fourier-Domain OCT(FD-OCT).Swept-Source OCT(SS-OCT)is a kind of FD-OCT technology,and its biggest feature is that it uses a swept source with good coherence.The swept source is one of the key parts of SS-OCT.The study in this thesis is a 1.3 ?m band short-cavity swept source,including:1.A short-cavity swept source with a center wavelength near the 1310 nm band was developed,the free spectral range reaches 297 nm.The scanning frequency of the swept source with this structure is 50 k Hz,the spectral scanning range is 100 nm,the duty cycle is 33% and the output power is 1 m W.Then,based on the four-wave mixing effect of light,a second swept source is developed,which has a scanning frequency of50 k Hz,a spectral scanning range of 130 nm,the duty cycle is 44% and an output power of 1.5 m W.Finally,based on Sagnac interferometer,a third structure of swept source is built,which has a scanning frequency of 50 k Hz,a spectral scanning range of 140 nm,the duty cycle is 47.5% and an output power of 2 m W.2.The engineering of the swept source was completed,the driving system of the swept source is designed and manufactured.The drive system consists of current drive module of SOA,temperature control module of SOA and polygon scanner driving module.Among them,the current drive module can stably supply 450 m A current to SOA,and the maximum fluctuation range of current is less than 2 m A in the continuous two-hour test.The temperature control module can stabilize the temperature of SOA at25?,in two consecutive hours of testing,the maximum temperature fluctuation does not exceed 0.05 °C.The polygon scanner driving module will provide a sine wave with a frequency of 1120 Hz and an amplitude of 2.5 V for the polygon scanner.In the continuous two-hour test,the maximum frequency fluctuation amplitude is 3 Hz and the maximum amplitude fluctuation amplitude is 0.1 V.Finally,the swept source and its driving system were engineered,and the engineering prototype of the swept source was designed,and the engineering of the swept source was completed.3.The engineered prototype of the swept source is applied to the SS-OCT system.The calculated theoretical axial resolution is 12 ?m.Then the 1 mm thick glass plate is imaged,and the surface of the glass plate can be clearly visible,but the lower surface is blurred,so the actual imaging depth of the swept source in the glass plate is 1 mm.Finally,the infrared card,finger and artificial eye were imaged,and get cross-sectional images of these samplesThe research results of this thesis are of great significance to the localization of swept source.