Single-pulsed digital holographic topometry

摘要

For the planning and documentation of maxillofacial surgery highly resolved tissue information is needed. In our approach, the surface of an object is displayed and measured with pulsed holography. With a single laser pulse (Nd:YAG) of 20 ns the object surface is recorded on a CCD sensor, movement artifacts are systematically avoided. With the knowledge of the recording parameters, the original wave field is synthesized numerically from the holographic interference pattern. The calculated slices are combined into an image stack, representing the digitized real image. This wave field represents the object geometrically correct, but focussed and unfocussed regions overlay. The focussed regions are identified numerically and combined into a height map, the texture information is extracted from the real image simultaneously. Both, height and texture are combined, yielding pixel-precise textured surface models. With this novel method it is possible to capture the surface of moving objects, even 3d motion series are possible. Skin can be detected in the real image, giving the potential application for facial measurements. Compared to our analog holographic topometry, there are still limitations regarding the extent of the imageable field and the axial resolution. The quick display of the reconstructed real image allows a direct appraisal of the object topology. This method is a valuable tool for the surface visualization of living subjects, offering potential for completely new fields of application.