LDV-based measurement of 2D dynamic stress fields in transparent solids

Laser Doppler Vibrometer (LDV) has been performed as a tool to observe stress fields of ultrasound longitudinal wave inside transparent solids due to its high sensitivity and intuitiveness. Besides, this method is only sensitive to dynamic stress and has no response to static stress, so it has the advantage of not being affected by residual stress in transparent solids. However, this method has limitations. LDV cannot directly detect shear wave, and for longitudinal wave, it can only obtain an approximate value of normal stress. In this paper, we analyze the limitations, and achieve observing shear wave by adding a rotatable linear polarizer to the optical system. Furthermore, the complete photo-elastic tensor can be obtained from the process of measuring longitudinal wave, and then the absolute 2D dynamic stress fields can be calculated. To check the applicability of our method, we compared LDV with the results of numerical analysis and dynamic photoelasticity, respectively.