Research On Tunable Laser Technology For High-speed PLIF Diagnosis

Planar Laser Induced Fluorescence(PLIF)is the technique of using the planar laser pulse to excitant fluorescence to record the transient flow field and flame structure.PLIF can get the temperature distribution,concentration distribution and flame structure and other information of certain gas molecules using laser excitation of freedom groups and ionic and analyze the fluorescence intensity and its two-dimensional spatial distribution.The technique of PLIF which is the main technology of fast changing flow field nowadays has the feature of high spatial resolution,short response time and high sensitivity.The PLIF usually requires the use of high-power,high-energy and tunable dye lasers.In order to meet the requirement of PLIF of the high frequency,high energy and narrow line wide tunable laser.In this paper,we carry out the research of high frequency and high power tunable laser.For the time domain characteristics of high frequency and high power tunable laser,the velocity of dye circulation system was get based on the dye thermal management flow and liquid flow stability,which is 10m/s.The fluctuate of output power of the laser was measured about 4%.Finally,the pulse width of tunable laser was measured of 8ns.For the frequency domain characteristics of high frequency and high power tunable laser,the line width compression technique of tunable laser was studied,and the line width was compressed by grating.The wavelength tuning technique of tunable laser was researched.The frequency doubling condition of tunable laser was researched.And the above research was actually measured.For the strength characteristics of high frequency and high power tunable laser,the conversion efficiency of the d ye laser was measured,which was about 20%.The output of base frequency light c ould reach 6m J.The effect of the oscillatory beam expander and pump light polarization state on the output energy of the laser were studied.Finally,the theoretical analysis and actual measurement of the frequency doubling efficiency could be up to 33%,and the output of the frequency doubled laser could be up to 2.2 mJ.