Research Of Gain Coefficient Measurment Of Stimulated Rotational Raman Scattering For Intense Laser Long Path Propogation

To obtain an accurate gain coefficient is critical for investigating the generationand growth of stokes pulse in stimulated rotational Raman scattering. However,there is no sufficient and systematic research achievement published until now. Inorder to guide the excogitation of terminal optics in inertial confinement fusiontarget, it is of great importance to measure the gain coefficient of stimulatedrotational Raman scattering for intense laser propagation in long air path in thelaboratory.Due to thermal dissipation of intense laser equipment, the time-intervalbetween pulses is relatively long, cannot obtain sufficient data; also, due to theaccuracy of metrology instrument, it is difficult but of great importance to obtain amore accurate gain coefficient with these data. Analyzed the accuracy of gaincoefficient obtained by least square method, then improved the data processingalgorithm, including Deming expanded LSM, variable-exchanged LSM, andunequally accurate LSM. Researched the results obtained by independentapplication and combinative application of such algorithm, then analyzed suitableconditions of them. When the error of measuring pump intensity is larger than thatof measuring Stokes intensity, Deming expanded LSM could be used, however it isnot strongly recommended because its complexity and unpredictable revise results;the results obtained by variable-exchanged LSM is similar to Deming expandedLSM, but much more easier and conspicuous, and could be used when the error ofStokes measurement is small. After obtaining the Stokes intensity, it should be takenthe logarithum, and then used for LSM, therefore the x variable should be treated asunequally accurate measurement, and should apply weighting LSM. However,considering the error in measuring pump intensity, weighting LSM can get a visiblyrevised result only when the error pump intensity is low.According to the result of research above, considering the operability ofexperiment and accuracy of result, propose the number of experiment samples, alsopropose methods to obtain a more accurate result as well as optimize suggestions.Providing references for future experiment.