Blood Pulsation Measurement Using Linearly Polarized Light

Blood molecules are optically active molecules. They have the ability to alter the polarization properties of light. This paper investigates the effect of blood pulsation variation on the polarization properties of linearly polarized light. This paper presents a new noninvasive noncontact blood pulsation measurement technique. Linearly polarized light has been allowed to transmit through the fingertips of a person and degree of linear polarization for transmitted part of the light has been calculated using polarized images. Experimental results show a strong correlation between the blood pulsation rate and the measured degree of linear polarization. The standard correlation coefficient value for the experiment with laser light source and two polarizers in the light path is 0.9484. Similarly for dc light source the correlation coefficient values are 0.9410 and 0.92 with two polarizers and one polarizer, respectively. Statistical analysis of the collected data has been done to measure the accuracy of the method. It shows that an accurate, low cost, and simple polarization-based blood pulsation measurement device can be developed by following the experiment performed with laser light source which could offer significant benefits to primary healthcare.