Dymamic signal processing and analysis in the OCT system for evaluating multilayer tissues

Non-destructive optical testing techniques are widely used in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for non-destructive investigations of paintings are available. Optical Coherence Tomography (OCT) is a non invasive technique allowing cross sectional imaging of partially transparent or scattering tissue which is now well-established for biomedical applications. Particularly, the OCT techniques allow evaluating multilayer tissues. Being applied to painting diagnostics, the OCT gives a possibility to measure the actual varnish thickness that is very important in painting restoration by the cleaning process. Because of complicated local structure of layers and light scattering, noise-immune signal processing methods should be used. In the paper, the Kalman filtering method involving random fringe model applied to the OCT signals is investigated and compared with conventional fringe amplitude demodulation method. Experimental results obtained when recovering OCT tomograms of paintings are presented and discussed.