Embedded Oct Integrated Control System Design And Development

Optical coherence tomography (OCT) is a recently developed high resolution biomedical imaging method, allowing for noninvasive visualizing of internal tissue structure and physiology. It is a new technology based on low coherence tomography, combining with the advantage of Confocal microscope and Heterodyne detection. OCT functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale. It is a promising imaging technology because it can provide images of tissue in vivo and in real time, without the need for excision and processing of specimens. OCT has been developed not only for morphological imaging, but also for functional imaging, such as spectroscopic imaging of tissue properties, Doppler blood flow measurement and quantification of blood oxygenation or tissue birefringence. By combining Doppler velocimetry with optical sectioning capability of OCT, we developed one branch of functional OCT (F-OCT) termed optical Doppler tomography (ODT).The goal of OCT system is applying in clinic widely and produces perfect social and economic benefits. That means applying integrated, intellectualized, miniaturized design, which is called embedded optimization design to various signal generators and control modules in OCT system, is the key to making OCT system low-cost, miniaturized and instrumented. This thesis analyses the principle of single-mode fiber- based OCT system and its working process. Then it puts forward a design thought. The design thought is to unify various modules to the embedded single-mode fiber- based OCT integrated control system. These modules include rapid scanning optical delay line (RSOD), detecting and scanning control signal, phase modulator and amplifying and filtering circuit of scanning signal and so on. The system regards ARM9 unit as the core. According to the design thought, the triangular wave for driving the galvanometer in the rapid scanning optical delay line, the square wave synchronized for the DAQ card and the high frequency sawtooth wave for the Phase Modulator are produced by high-speed DA chips and its relevant logic circuits. At the same time, the stepping motor and the displacement console in the detecting and scanning control signal module are directly controlled by driving chips and its relevant logic circuits, all the chips are in the core of ARM9 unit. Therefore, the whole system discards the discrete fiber-based OCT system structure. The discrete system structure is a complex system that made up of many general instruments, As a result, it has a high cost. Our design thought also introduces embedded Linux OS to the fiber- based OCT system, so the system has such features as excellent extensibility, good stability and strong real time control function. It also has a low cost in development and production. Experimental results show that the fiber- based OCT control system with embedded design can meet the requirement of scanning speed, scanning area and imaging resolution.