Ultraviolet Diffraction Assisted Image Correlation (UV-DAIC) for Single-Camera 3D Strain Measurement at Extreme Temperatures

Diffraction Assisted Image Correlation (DAIC) measures three-dimensional (3D) full-field deformations using a single camera. This is accomplished by placing transmission diffraction gratings between the specimen and camera to produce multiple views of the specimen at different angles. The angle at which the image appears depends on the wavelength of light used for illumination, the pitch of the gratings being used, and the diffraction order of the image. In this work, DAIC is modified for use at a higher range of temperatures by using ultraviolet (UV) light for illumination and filtering out the visible spectrum light emitted by high temperature samples. These images were then used for 3D displacement and strain measurements using stereo digital image correlation (3D-DIC). This method was first tested at room temperature by comparing results to known deformation applied as rigid body motion. It was then demonstrated to be effective in making displacement and strain measurements up to a temperature of 900 °C.