Dynamic speckle analysis with two-wavelength acquisition

Dynamic speckle analysis is a promising tool for inspection of speed of processes. It relies on highly sensitive of speckle phenomenon to micro-changes in the optical paths. The same phenomenon is a source of severe noise, which contaminates substantially the outcome of analysis when a pointwise processing is applied to correlated in time speckle patterns. We obtained improvement of quality of the two-dimensional activity map produced by the pointwise processing by illumination at two wavelengths in the red and green part of the spectrum and separate processing of the raw data acquired in the red and the green channels of a color camera used to capture the speckle patterns. Summation of the activity maps corresponding to the two channels results in narrower spread of fluctuations of the estimate chosen to describe the activity.