Holographic measurement of microscopical sliding of electrical contact due to contact spring thermal deformation

The authors have developed a holographic pattern measuring system (HPMS) which combines the techniques of holography and graphic image processing. The HPMS was applied to the study of the thermal deformation of a contact spring. Using this approach, the microscopic displacement of the contact spring could be quantitatively measured in a noncontact way, and the distribution of the displacement could be shown automatically as a three-dimensional graphic image. In the case of thermal excitation by the current flow through the electric contact, a quantitative correlation between the slide of the contact point and the thermal deformation of the contact spring was obtained. In addition, the authors found some irregularity in contact voltage when the current flowed through the closing contacts. From the deformation analysis of the contact spring, the relationship between the contact voltage and the deformation of the contact spring due to current flow was made clear.