Noncontact elastography of soft material using a laser profilometer with airpuff excitation

Elasticity is a fundamental property of materials, and recent advancements in wave-based elastography have revealed significant potential for various biomedical and engineering applications, including biomedical imaging, nondestructive evaluation, and structural health monitoring. However, the implementation of elastography requires high-precision imaging systems, which limits its broader applicability. The laser profilometer, a conventional and cost-effective device that operates based on laser triangulation measurement, has been widely utilized in industrial applications for assessing surface profiles. However, its application in elastography has not been previously explored. This study represents, to the best of our knowledge, the first attempt to adapt a laser profilometer for measuring the elasticity of soft materials. A simple and noncontact method for measuring elasticity has been established utilizing the laser profilometer to track the propagation of surface waves on soft materials when excited by an airpuff. The results demonstrate that laser profilometer elastography can track the propagation of surface waves with a broad spectrum following a single airpuff excitation. The temporal separation of wave propagation from the reflected waves enables precise calculation of the propagation velocity of surface waves. The surface wave velocities measured by laser profilometer elastography and laser speckle elastography show strong agreement with a correlation coefficient of 0.997. Additionally, the shear elastic modulus of agarose phantoms has been validated by comparing the results obtained from a rotary rheometer. This approach improves the noncontact elastic measurement capabilities of traditional laser profilometers by only utilizing an airpuff system. Therefore, it has the potential to expand a new application of laser profilometers and be widely utilized for elasticity measurement in both biomedical and industrial applications.