Holographic interferometry applied to the study of the human skull

A laboratory technique that allows strain measurements of the skull is described. Holographic interferometry allows the entire surface displacement of the skull to be mapped within 1/10 of the wavelength of light. Holographic interferometric pictures are presented following various stress applications to the skull. The method, besides being exquisitely sensitive, allows strain measurements simultaneously in any desired direction over the entire skull. No physical contact with the skull is required, and the experimental set-up is simple.