Circular birefringence/dichroism measurement of optical scattering samples using amplitude-modulation polarimetry

Abstract

A method is proposed for extracting the circular birefringence (CB), circular dichroism (CD) and depolarization (Dep) properties of optical scattering samples using an amplitude-modulation polarimetry technique. The validity of the proposed method is demonstrated by extracting the CB property of pure glucose aqueous samples, the CB/Dep properties of glucose solutions containing 0.02% lipofundin particles, and the CD/Dep properties of chlorophyllin solutions containing suspended polystyrene microspheres. The results show that the proposed technique has the ability to detect pure glucose with a resolution of 66 mg/dL over a concentration range of 0–500 mg/dL. Moreover, the glucose concentration of the CB/Dep samples can be detected over the same range with a resolution of 168 mg/dL. Finally, the chlorophyllin concentration of the CD/Dep sample can be detected over the range of 0–200 μg/dL with a resolution of 6.5 × 10−5. In general, the results show that the proposed technique provides a reliable and accurate means of measuring the CB/CD properties of optical samples with scattering effects, and thus has significant potential for biological sensing applications.