Holographic investigation of the impact response of human heads.

The impact response of intact human cadaver heads was studied by means of double-pulsed holography using a ruby laser, and the transient deformation process at the surface of the skull was recorded. Frequency and acceleration measurements following impact were obtained. On frontal impact, the shock wave reached the opposite pole after 0.2 to 0.3 msec, and maximum amplitudes were found in the temporal regions. On impact to the vault, the deformation wave reached the skull base after 0.15 to 0.175 msec. Centers of maximum amplitude were recorded in the parietal and temporal regions. Deviations in the interference lines occurred at some sutures, revealing discontinuities. High-frequency components of the shock wave were demonstrated. The authors believe that fracture mechanisms may be elucidated by further studies of impact responses.