The microstructure of explosives has a decisive impact on the safety of energetic materials. Phonons, as energy carriers, significantly influence the transport and evolution behavior within explosive microstructural regions. Understanding their behavior is essential for comprehending the mechanisms behind hot spot formation in explosives. Using laser ultrasonic Lamb wave detection methods, it is possible to measure large-area signals without physical contact, thereby obtaining information about microstructure and mechanical properties. We developed an ultrafast optical technique using the 4f system for real-time, high-resolution elastic wave propagation monitoring in glass plate. By performing two-dimensional spatiotemporal Fourier transform on experimental data, we can derive the dispersion relation of acoustic phonon wavepackets. The dispersion relationship informs about frequency as a function of wavenumber, essential for understanding relation between material microstructure and physical properties. The experimental results we obtained are consistent with theoretical predictions, thus verifying the feasibility of our experimental technique. This technique not only demonstrates potential for elastic wave propagation monitoring but also facilitates dynamic parameter extraction to obtain dynamic information about acoustic phonon wavepackets transport in microstructured energetic materials.

energetic materials,spatiotemporal resolution,phonon transport,dispersion relation