Reflective high-sensitivity polarization change imaging using a dual polarizer structure

Abstract

In this study, we demonstrate a reflective imaging system in which a dual polarizer structure, consisting of a uniform polarizer and a polarizer on the pixel of a polarization image sensor, enables the detection of weak polarization changes. The uniform polarizer can achieve a high extinction ratio and is used to render the amount of polarization change in a condition that is easily detectable by the polarization image sensor. The polarization image sensor uses two types of polarizers arranged in an orthogonal relationship with each other to obtain complementary signals for polarization rotation. This is also used for differential detection to reduce the in-phase noise components. In the prototype system, the signal characteristics were in close agreement with theoretical considerations. Furthermore, as a demonstration of high-sensitivity polarization rotation imaging, the polarization rotation of a menthol solution in a 150-µm-thick channel was detected.