Birefringence measurements of aqueous cellulose nanocrystal (CNC) suspensions are reported. Seven suspensions with concentrations between 0.7 and 1.3% per weight are sheared in a Taylor-Couette type setting and characterized using a birefringent measurement technique based on linear polarized light and acquisition with a polarization camera. Steady state measurements with shear rates up to 31 1/s show extinction angles of 23°–40° and birefringence in the order of 1e–5. The findings demonstrate the utility of CNC suspensions for flow birefringence studies.
Polarization measurements conducted with a polarization camera using the Sony IMX 250 MZR polarization image sensor are assessed with the super-pixel calibration technique and a simple test setup. We define an error that quantifies the quality of the polarization measurements. Multiple factors influencing the measurement quality of the polarization camera are investigated and discussed. We demonstrate that polarization measurements are generally consistent throughout the sensor if not corrupted by large chief ray angles or large angles of incidence. The central
600
×
400
p
i
x
e
l
s
were analyzed, and it is shown that sufficiently large
f
-numbers no longer influence measurement quality. We also argue that lens design and focal length have little influence on these central pixels. The findings of this study provide useful guidance for researchers using such a polarization image sensor.
A two-dimensional birefringence measurement method is described. In
this procedure, we send light through a rotatable linear polarizer and
subsequently through a transparent and birefringent specimen. A
polarization camera measures the state of linear polarization from
which the relative position of the refractive index axes and the
relative phase difference is determined. The measurement range of the
phase difference is up to
π
rad, which corresponds to an optical
retardation of half the wavelength of the light. The imaging system
can measure a large sample area within one measurement cycle.
Measurement performance is demonstrated with a quarter-wave plate, and
an exemplary test case is shown.
Birefringence measurements of aqueous cellulose nanocrystal (CNC) suspensions are reported. Seven suspensions with concentrations between 0.7–1.3 percentage per weight are sheared in a Taylor-Couette type setting and characterized using a birefringent measurement technique based on linear polarized light and acquisition with a polarization camera. Steady state measurements with shear rates up to 31 1/s show extinction angles of 23–40° and birefringence in the order of 1e-5. The findings demonstrate the utility of CNC suspensions for flow birefringence studies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.