Design And Implementation Of Photoacoustic Signal Conditioning And Synchronization Control

Photoacoustic tomography which has both optical and acoustic characteristics is different from other imaging system, has important significance in optical and biomedical research. This article implements a set of signal conditioning modules according to the existing photoacoustic imaging system can not realize gain compensation and slow scanning speed of the stepper motor. Complete galvanometer-driven to realize line scanning, hardware gain compensation and synchronization on the whole system. In the first, an introduction of the existing system with signal conditioning system PR5800is given; it could not realize the gain compensation. And the scanning system is stepper motor that adjusted the step by hand that can scanning one point at one times. Also the laser trigger system was inner trigger, unable to control the laser system makes it impossible to control the received ultrasound signal, the above system was improved.In this paper, the major work including:some excellent integrated chip was selected to realized fronted signal conditioning modules whose gain can be adjusted, according to the characterization of photoacoustic signal and the ultrasound signal received by transducer. To overcome the drawback of the slow scanning speed of step motor, galvanometer-driven module including DA converter, current to voltage was designed, also the hardware circuits implementation was finished, the detail information about design and simulation was given also. External trigger pulse was designed by FPGA according to the characteristic of the existing laser systems, confirmed the useful ultrasound signal location in time-domain by controlling the laser trigger pulse. Make the controlling of the photoacoustic system easier safer compare with the traditional ultrasound system. Synchronization principle of the laser triggers pulse, gain control, and galvanometer deflection, also the synthesization of the system controlling chart in ISE13.1environment and the explanation was given. At last, an experiment about the gain control was given which using analog sample buried with pencil core to test and verify the performance of gain control, also the comparison between the designed system and the existing PR5800, and analysis about the system performance and drawback was showed. Experimental results showed that the gain compensation was achieved, and had certain reference value for the photoacoustic imaging.