Design and Implementation of Real-Time Fluorescence Triple Correlation Spectroscopy Correlator Based on FPGA
To meet the requirements of multichannel fluorescence correlation spectroscopy with a wide dynamic range,a digital correlator based on field programmable gate array(FPGA)technology was designed and implemented.The hardware structure was designed and implemented using a register-level hardware description language.Based on the characteristics of photon pulse counting signals,the multi-sampling-time correlation and time-division multiplexing methods were used to calculate the correlation function,which substantially improved computing efficiency and optimized hardware resource utilization.The time-division multiplexing of cross correlation was extended to triple correlation,and the corresponding method was extended to adapt triple correlation.Ultimately,a real-time computing triple correlator based on FPGA was realized.The calculation method of symmetric normalization ensured the accuracy of the correlation function.The designed photon correlator was implemented based on a single Xilinx Zynq-7100 FPGA chip,which performed various functions,including the real-time correlation of three channels auto-correlation,three channels cross-correlation,and one channel triple correlation,with the time resolution of 40 ns and dynamic range of 1.57×107.