Laser speckle is an interference phenomenon that is observed when coherent light (e.g.laser ) is scattered from a diffusing surface. In general, a speckle pattern is a random pattern whose properties can be described using stochastics and probabilistic laws.
The standard deviation (s) of the intensity distribution in the speckle pattern is one of the most common and useful statistics, and the quotient between standard deviation and mean (m) intensity is used to define contrast (C), a standard metric used in speckle patterns analysis. C=s/m
New image processing techniques have been used to quantify the change in the speckle pattern, as a consequence of the micromovements ( in dynamic speckle) of the surfaces being studied. These techniques include Pattern Analysis and unsupervised Machine Learning algorithms whose study is being done in our research group. The use of stereoscopic speckle analysis is also under study in the context of skin microcirculation analysis.
Speckle imaging is a noninvasive imaging technology having high potential in terms of industrial applications and material engineering, but also in the context of Medical Imaging, which is the main research interest within LaserLabMed research team.
Some examples of Medical Applications of Laser Speckle include:
Legend: Time History Speckle Image (THSP) with high activity Legend: Time History Speckle Image (THSP) with Low activity
- Gonzalez, M., Azul, Guzman., Nicolas, M., Fonseca-Pinto, R., Trivi, M., Rabal, H., Passoni, I. L., “Qualitative characterization of skin tissue with Dynamic Laser Speckle”, Revista Argentina de Bioengenieria, 22(1), 2018;
- L. Bento, L. Távora, P. Assunção, S. Faria and R. Fonseca-Pinto, "Using local binary patterns in speckle image analysis," 2018 41st IEEE/ International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), Opatija, Croatia, 2018, pp. 0167-0171. DOI: 10.23919/MIPRO.2018.8400033
- L. Bento, L. Távora, P. Assunção, S. Faria and R. Fonseca-Pinto, "Evaluation of cutaneous microcirculation patterns by laser speckle imaging," 2018 41st IEEE/ International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), Opatija, Croatia, 2018, pp. 0290-0293. DOI: 10.23919/MIPRO.2018.8400055
- Bento, L., Távora, L., Assunção, P., Faria, S., & Fonseca-Pinto, R. Dynamic Laser Speckle in Medical Imaging: On the quantification of skin patterns. Encontro Nacional de Novos Investigadores em Saúde & International Meeting of New Health researchers, Vol2, pp. 36, 2017
Rui Fonseca-Pinto - Multimedia Signal Processing Group - Lr