Digital holographic microscope for high spatial and temporal resolution in situ observation of dynamic phenomena of metals

A digital holographic microscope (DHM) was developed for the purpose of simultaneous observation and measurement of surface relief formation during deformation and phase transformation of steels. It was designed to accommodate the sample mounting component of a custom tensile tester. The Gabor wavelet transform method was used in the image reconstruction. To verify performance, the DHM was used to observe and measure height of slip bands formed during the monotonic loading 316L stainless steel. Data obtained has high temporal resolution (limited only by the camera’s frame rate capability) with lateral resolution approaching the diffraction limit. The results clearly show the evolving microstructures with height information available within each captured image.