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针对短脉冲激光入射一维非均匀参与性介质问题,计算了非均匀体的大小、位置以及吸收和散射系数对边界出射信号的影响。依据各参量敏感系数的变化,确定了信号采样的时间范围。利用共轭梯度法对非均匀体进行多参数同时反演。数值模拟结果表明,对同一非均匀介质,不同的入射位置会得到不同的敏感系数,且各参数敏感系数明显变化的时间段不尽相同,但多数变化信息包含在两倍脉冲穿越时间内。在反问题计算中,推荐选用两倍脉冲穿越时间内的信号作为采样数据。共轭梯度法能较为准确地实现介质多参数同时反演。随着测量数据误差的增加,反演结果与真值之间的偏差增大。敏感系数值较小的参量,其反演计算结果误差较大。
Aiming at the problem of one-dimensional inhomogeneous medium incident by short-pulse laser, the influence of the size, location and absorption and scattering coefficients of inhomogeneous bodies on the boundary emission signal is calculated. According to the change of sensitivity coefficient of each parameter, the time range of signal sampling was determined. Using Conjugate Gradient Method to Perform Multi-parameter Simultaneous Inversion of Nonuniformity. The results of numerical simulation show that different sensitivities are obtained at different incident positions for the same inhomogeneous medium, and the time periods for significant changes of sensitivities of each parameter are not the same, but most of the variation information is included in the twice-pulse traversing time. In the calculation of inverse problems, it is recommended to select the signal within twice the pulse traversal time as the sampling data. Conjugate gradient method can more accurately achieve the simultaneous inversion of multiple parameters of the medium. As the error of the measured data increases, the deviation between the inversion result and the true value increases. The parameters with smaller sensitivity coefficient have larger errors in the inversion results.