Status of Dual-Laser Digital Holography for Surface Characterization at ORNL

A dual-laser differential digital holography system is under development at Oak Ridge National Laboratory (ORNL) for 3D measurement of surface erosion of plasma facing component (PFC) materials. Digital holography produces topological data of a target from IR laser interferometry. The system is capable of a depth resolution range perpendicular to the surface of 100 nm to 4.5 μm (single-laser holography) and up to 2 mm for dual-laser differential holography. Transverse resolution of the measurements is limited by diffraction effects, covering an area of 7x7 mm² with a 1X magnification lens. Holograms produced “on the bench” of test targets have shown that the system can produce measurements from <1 μm to ~2 mm total depth, demonstrating good progress towards deployment in the field. Measurements of Proto-MPEX plasma-exposed targets, including a SiC target, have been made. Status of the dual-laser system and progress in single- and dual-laser measurements will be presented.