DYNAMIC DIGITAL HOLOGRAPHY BASED ON TEMPORAL DOMAIN HILBERT TRANSFORM PHASE ANALYSIS

摘要

In this study, we have proposed a novel digital holographic technique that permits to observe a dynamic deformation of an object. The digital holography has various advantages such as a high spatial resolution and reconstruction of object at an arbitrary depth. However, because of the low spatial resolution of CCD camera, optical setup of in-line hologram has been used. In this case, phase shifting technique has been effectively used to determine the complex amplitude on the recording plane. In the method, however, the object has to be static during the acquisition of the phase shifted interference images, and this makes it difficult to apply the technique to the dynamic events. In contrast, our method employs a temporal domain Hilbert transform phase analysis to determine the dynamic complex amplitude on the hologram plane. Preliminary experiments were carried out to demonstrate the validity of the method. In the experiments, a cupper plate of the size, 100×50mm, was sinusoidally deformed with amplitude of 500nm by PZT. The temporal carrier was introduced to solve a sign ambiguity of the deformation. The measured maximum deformation was 475nm, and thus the measurement accuracy of 95% was achieved to the maximum deformation.