Transformation of laser-induced broadband pulses of longitudinal ultrasonic waves into pulses of shear waves and back into pulses of longitudinal waves (further called as the “double” transformation) in an isotropic solid plate immersed in a liquid is theoretically studied. It is shown that the time profile of the pulse of shear waves strongly depends on the angle of incidence and only at a certain value of this angle the time profiles of the incident longitudinal-wave pulse and induced shear-wave pulse coincide. For various angles of incidence, the broadband pulses of longitudinal waves experimentally obtained after the double transformation in an aluminum and fused silica plane-parallel plates immersed in distilled water correspond to the theoretically calculated profiles except for the increased duration of experimental pulses. Based on the double transformation scheme, the method of broadband acoustic spectroscopy of longitudinal and shear waves for isotropic solid plates in the spectral range of the blue-green glass laser source of ultrasound (1–40 MHz) was proposed and experimentally realized for the first time. The obtained frequency dependences of the attenuation coefficients of longitudinal and shear ultrasonic waves in stainless steel, cast babbit, and brass can be used for appropriate choice of an operating frequency range by ultrasonic nondestructive testing of these materials.

理论上研究了在浸入液体中的各向同性固体板中，激光诱导的宽带纵波脉冲转换为横波脉冲并返回纵波脉冲（进一步称为“双”转换）。结果表明，横波脉冲的时间分布强烈依赖于入射角，只有在该角度的某个值处，入射纵波脉冲和感应横波脉冲的时间分布才一致。对于不同的入射角，在浸入蒸馏水中的铝和熔融石英平面平行板中经过双重变换后实验获得的纵波宽带脉冲与理论计算的轮廓相对应，除了增加了实验脉冲的持续时间。基于双变换方案，提出了蓝绿玻璃超声激光源（1-40 MHz）光谱范围内各向同性固体板的纵横波宽带声谱分析方法，并首次实现了实验实现。时间。The obtained frequency dependences of the attenuation coefficients of longitudinal and shear ultrasonic waves in stainless steel, cast babbit, and brass can be used for appropriate choice of an operating frequency range by ultrasonic nondestructive testing of these materials.