Two-Frequency Speckle Analysis of Plasma Clotting Time

The paper presents the results of evaluating the prothrombin time of blood plasma by the method of digital speckle patterns correlation, formed by semiconductor laser diodes with wavelengths of 635 and 650 nm. The experimental results obtained show, that the wavelengths used in the analysis allow getting a reliable result. The change in the correlation coefficient at both wavelengths is almost the same. The use of two sources with alternate switching will increase the reliability of the system and minimize random error. The paper provides curves of the correlation coefficient versus time and a comparative graph of 15 experiments conducted using the proposed laboratory setup.