Experimental study on simultaneously measuring Young's modulus and internal fraction using self-mixing system

Material parameters such as Young's modulus and internal friction are important for estimation of material performance. This paper presents an experimental study for measuring material related parameters using a selfmixing interferometric (SMI) configuration. An SMI system consists of a laser diode (LD), a lens and an external target to be measured. When a part of the lasing light back-reflected or back-scattered by the external target re-enters the LD internal cavity, both optical frequency and intensity of the lasing light can be modulated. This modulated laser intensity is often referred as SMI signal. Generally, the target related movement or its surface information can be retrieved from this SMI signal. In this paper, an SMI system is implemented. A tested sample is used as the target to form the external cavity of the LD. The tested sample is stimulated in vibration. Continuous wavelet transform (CWT) is utilized to retrieve the vibration information of the tested sample from an SMI signal. We are able to obtain both Young's modulus and internal friction from a piece of an experimental SMI signal. This work provides a novel, simple non-destructive solution for simultaneous measurement of Young's modulus and internal friction.