| The photoelectric detection system is an important part of photoelectric detection equipment,which mainly composed of the photodetectors and the current amplifiers.The photodetectors convert the light signal to be measured into a current signal,and the current amplifiers convert this current signal output from the photodetectors into a voltage signal.In order to be able to completely and accurately detect the relatively weak and short duration of the optical signal,we need to balance the gain,bandwidth and noise of the photoelectric detection system in the design process.’This paper studies the research status of photoelectric detection system at domestic and abroad,and analyzes the working principle,the components and the design difficulties in detail,and designs a high accuracy photoelectric detection system.The photomultiplier(PMT)module is selected as the system’s photodetector,since it has very high internal gain,high sensitivity and short response time compared to other detectors.The general current amplifier consists of a preamplifier and a voltage amplifier,where the design of the preamplifier is difficult.In order to explore the impact of printed circuit boards(PCBs)and sapphire materials on current amplifiers,the two materials were used as base boards and were tested in the laboratory.When the input of the current amplifier(106 V/A)is shorted,the output noise peak-to-peak of two different circuits are about 3mV.In addition,in the case of no optical signal input,and the overall gain and bandwidth of the photoelectric detection system are kept constant,the output noise under different gain allocations is measured.When the control voltage of the PMT module is 0.49 V,the gain of the current amplifier based on the sapphire socket is 2×105 V/A,the system output noise is low and the peak-to-peak value of is about 4.56 mV.This photoelectric detection system was measured in a 2016 winter trial experiment in the Experimental Advanced Superconducting Tokamak(EAST)device.The experimental data showed that the system can detect edge localized mode(ELM)events at different frequencies and edge oscillations at frequencies of several kHz.Therefore,the developed photoelectric detection system will be helpful for the study of ELM properties and H-L transitions. |
