Building an Automatic Control System for Measuring the Stokes Parameters

Abstract

Many researches have shown the potential of polarized light in inspection and diagnostic. Such as the ability to determine sugar concentration in the cornea which could be developed to non-invasive polarimetric glucose detector for diabetic’s detection; or diagnose vascular disease and brain function by detecting the concentration of the deoxygenated hemoglobin in vein. Additionally, the Polarization properties of scattered light from turbid media such as biological tissues and certain plastics have also received considerable attention. From the scattered light of a sample, fundamental optical properties of the sample could be revealed. From this information, some diseases could be detected, including diabetes, cancer. In this research, an automatic Stoke parameters measurement system is introduced to determine the fundamental optical properties i.e., the effective linear birefringence (LB), linear dichroism (LD), circular birefringence (CB), circular dichroism (CD), linear depolarization (LDep), and circular depolarization (CDep) of a biological sample. By measuring Stokes parameters of 6 kinds of polarized lights (right-hand circular, left-hand circular, 0°, 45°, 90°, 135° of linear polarized lights) which are projected through the biological sample. The results showed that the system can automate measure Stokes parameters of a biological sample with the accuracy ±5% to compare with the commercial device, Stokes polarimeter. From this raw system, the developing of the system is improved for diagnosing cancer.