Single-shot digital image-correlation-assisted digital holography for simultaneous 3D shape and displacement measurement

To measure surface 3D shape and displacement of curved diffuse objects, existing holographic techniques usually rely on complex optical systems or multiple shots. This is because digital holography (DH) can only measure displacement along the direction of the sensitivity vector. To realize 3D displacement measurement, three DH setups are needed. Meanwhile, a single-wavelength DH setup cannot measure the 3D shape of curved diffuse objects. To accomplish the goal of simultaneous 3D shape and displacement measurement of curved diffuse objects, a single-shot DH with a simple setup is proposed. Based on the combination of dual-wavelength DH (DWDH), digital imaging correlation (DIC), and spectrum multiplexing, the proposed technique only adopts a simple DH setup to accomplish the above task in single-shot. Specifically, spectrum multiplexing enables single-shot recording. DWDH allows the 3D shape measurement of curved diffuse objects and extends depth displacement measurement range. DIC-assisted DWDH fully utilizes DWDH's information for simultaneous 3D displacement measurement. Experiments performed on diffuse objects validated the proposed method, which would expand DH's applications in 3D dynamic measurements and 3D large displacement measurements.