Self-tuning laser speckle contrast analysis based on multiple exposure times with enhanced temporal resolution

Abstract

Laser Speckle Contrast Analysis (LASCA) was introduced in 1981. Since then, several enhancements were applied to it. Nowadays, the technique can provide relatively high accuracy as well as high temporal and spatial resolution during the examination of ocular or cerebral tissues. However, in the case of skin, the results are highly affected by the intensive scattering on the skin surface, as the scattering on the non-moving parts of the sample lead to the detrimental decrease of the accuracy. We present a LASCA method based on the use of multiple exposure times, combined with the switching-mode control of the light intensity and a special sampling technique to achieve near to real-time measurement of the skin perfusion. The system based on our method is able to automatically handle the destructive effect of the skin surface and re-tune itself according to the changes of the sample, while it provides full-field perfusion maps with high accuracy, without the need of any precalibrations.