Polarization phase unwrapping by a dual-wavelength Mueller matrix imaging system

Abstract

In this Letter, we report a dual-wavelength Mueller matrix imaging system for polarization phase unwrapping, allowing simultaneous acquisition of the polarization images at 633 nm and 870 nm. After phase unwrapping, the relative error of linear retardance is controlled to be 3% and the absolute error of birefringence orientation is about 6°. We first show that polarization phase wrapping occurs when the samples are thick or present obvious birefringence effects, and further analyze the effect of phase wrapping on anisotropy parameters via Monte Carlo simulations. Then, experiments on porous alumina with different thicknesses and multilayer tapes are performed to verify the feasibility of phase unwrapping by a dual-wavelength Mueller matrix system. Finally, by comparing the temporal characteristics of linear retardance during tissue dehydration before and after phase unwrapping, we emphasize the significance of the dual-wavelength Mueller matrix imaging system not only for anisotropy analysis in static samples, but also for determining the trend in polarization properties of dynamic samples.

Exploring the unique and coupled effects between birefringence and scattering via a novel approach

“…However, for both the pure birefringence system in Section 3.1 and the system discussed in this section, phase wrapping effect, as seen in Fig. 8(b), emerges with increasing birefringence 32 .…”

Creep Monitoring of Submersible Observation Windows Using Mueller Matrix Imaging

“…This indicates that R can also characterize the creep effectively. It should be noted that the retardance R is subjected to a π period [ 36 ], which affects the experimental results and needs further study.…”

Evaluating backscattering polarized light imaging microstructural mapping capabilities through neural tissue and analogous phantom imaging

“…This has been observed in work by other groups working with Mueller matrix polarimetry as a result of a phase wrapping artifact. [52][53][54] Depicted in Fig. 4(a), a retardance plot in which we expect to see the retardance changing monotonically along the length of the fibers and a corresponding retardance angle plot in which we expect the retardance angle to be consistent along the length of the fiber, but we instead see a 90-deg discontinuity.…”

“…The inverse cosine function is intrinsically bounded from zero to π radians, but as the Mueller matrix components corresponding to retardance continue to increase past what would be π radians the output retardance is mirrored around π due to the even nature of the cosine function. 52 It can be somewhat difficult to discern in retardance data; however, this phase wrapping also affects the calculation of the retardance axis of the material, resulting in a 90-deg offset in the retardance angle data, as shown clearly in Fig. 4(a).…”

“…4(b). To do so, we take what we believe to be the affected portion of the signal and either subtract it from 2π if it is mirrored around π or make it negative if it is mirrored around zero; additionally, we can apply a correction to the retardance angle data by adding 90-deg to the offset angular portions of the data, similar to the methods laid out in Song et al 52 This correction clarifies some ambiguities in the data; however, there is a subjective nature to them in determining which parts of the data have undergone phase wrapping due to the relative nature of the retardance measurements. In this work, we mainly relied on the convention that we expect to see a reduction in retardance as wavelength increases, as predicted by our theoretical model.…”