Evaluation of thermal expansion of elastomer using self-mixing vibrometry with thin-slice solid laser

Abstract

We describe an easy, non-destructive, and non-contact method for observing deformation of thermally degraded rubber by using the self-mixing laser Doppler velocimetry method. In this method, a laser light called a pump beam, whose intensity is periodically modulated, illuminates the surface of the rubber to deform it through thermal expansion. Then, a laser light called a probe beam illuminates the surface of the rubber to observe and measure the deformation. The time dependence of the deformation obtained by performing a Hilbert transform on the resulting modulated wave from the surface can be measured with high spatial resolution. The relationship between the time dependence of the deformation and the hardness of the rubber is discussed.