Detection of Defects in a Dielectric Material by Thermo-Elastic Optical Indicator Microscopy

We present a new optical method for the detection of defect in dielectric materials. This method is based on the optical visualization of the microwave near-field distribution around defects in a dielectric material. In this study, we visualized the microwave near-field distributions in various types of defects in dielectric plates through thermoelastic optical indicator microscopy. The experimental results showed that the microwave near-field distribution around the defect appears in various forms depending on the structure of the defect. From the experimental results, it was shown that the present method can provide information on the position and structure of defects in dielectric materials in a non-contact, non-invasive and non-destructive manner.