Research On Controlling And Testing Technology Of High-speed PLIF Detection System

High-speed PLIF detection system, as an important part of the high-speed PLIF imaging system, can quickly and effectively detect weak fluorescence signals. The detecting system is composed of an image intensifier and a high-speed camera; however, due to the limitations of the data transfer rate of the instrument interface, the current detection systems usually store pictures in the memory of the high-speed cameras, and then manually export by third-party software. The high-speed PLIF system cannot continuously work for hours due to the limitation of the camera’s internal memory. From the perspective of high frame rate, high sensitivity and continuity, the controlling and testing technology of the high-speed PLIF detection system was studied.The structure of the high-speed PLIF detection system was designed, the current gain of the image intensifier and its noise characteristics were introduced and also the noise characteristics of CMOS high-speed camera were analyzed. The expression of the system noise factor was derived in this paper, using cascaded model. This model was based on the noise factor of each hardware component. Theoretical calculations show that the system noise factor increases with the gain voltage of the image intensifier decreases.In the consideration of the practical application background of high-speed PLIF imaging system, two different operating modes were designed: REPETITION MODE and BURST MODE. The hardware construction was finished according to these two modes; the controlling software with high-performance was developed with Lab VIEW. A high-precision timing control technology with the accuracy of picosecond was described in this paper; a high-speed dynamic data acquisition technology with speed of more than 500 M / s was also described.System noise test experiment found that dark current noise and 1/f noise of high-speed CMOS camera can be negligible when the frame rate exceeds 100 Hz and above; The dark current noise of image intensifier exponentially grow when gain voltage exceeds 800 V. In REPETITION MODE(500-1000Hz), a photo detector with high-precision and high linearity was used for the correction of power jitter of the laser light source in the experiment, The experiment provided a method to get noise factor of the detection system, experimental results show that, the SNR of the detection system exponentially increases with the voltage across the MCP increases when MCP has not reached the saturation. Using a 532 nm half-wave plate, a polarizer and a precision rotating platform to system to characterize the optical power response of the detecting system, the experiment results show that the system has a good linearity of the optical power response. The detecting system has a dynamic range of about 9n W and the minimum detectable optical power is 3n W ~ 4n W when the voltage across MCP is 769.1V.