Laser Speckle Stereo System in Biomedical Imaging

摘要

Speckle is an optical interference phenomenon generated by the reflection of a highly coherent beam of light (e.g., laser) on a rough surface. This phenomenon has been applied in several research areas, aiming at the characterization of static surfaces or the extraction of properties in dynamic processes. In particular, laser speckle has shown huge potential in the identification of high varying perfusion regions in medical images of skin and brain. The acquisition setup in laser speckle is usually composed by a laser source, a magnifying lens, and one video camera. From the obtained sequence of video frames several image descriptors are calculated to characterize the surface under analysis, using information obtained from the scattered patterns. In recent years a new acquisition perspective in laser speckle was proposed by assembling an acquisition setup using two video cameras, thus producing the so called stereo laser speckle. This new approach is challenging regarding acquisition and imaging processing, introducing several variables to be controlled (distance from the camera lens to the surface, direction and width of the reflected beam of light). In this paper, a revision of recent results in stereo laser speckle is presented, highlighting the challenges in acquisition and image processing. Moreover, a new setup is proposed to test the influence of the identified critical variables in stereo laser speckle to be applied in medical imaging contexts.