Fig 1.
Schematic illustration of the scanning cryomacroscope setup incorporating polarized-light means.
Via an integrated graphical user interface, independent computerized means (not shown) are used to control the scanning mechanism of the cryomacroscope, to streamline images from the CCD camera, and to log temperature data from strategically located sensors. The cooling chamber is independently controlled by a commercial programmable controller. A more detailed setup is presented in [30].
Fig 2.
Schematic illustration of the experimentation stage of the scanning cryomacroscope, incorporating polarized-light means.
(a) Isometric view including all illumination components. (b) Side view highlighting the light polarization and filtration components. where the red-dashed arrows represent the direction of polarized light illumination. (Reprinted from Cryobiology, 73(2), Feig, J. S. G., Eisenberg, D. P., and Rabin, Y., Polarized light scanning cryomacroscopy, part I: Experimental apparatus and observations of vitrification, crystallization, and photoelasticity effects, pp. 261–271, Copyright (2016), with permission from Elsevier).
Fig 3.
Geometric model and frame of reference for polarized light investigation.
Presentation of three representative paths of light, P0, P1, and Pmax (colored arrows) and a frame of reference for light refraction analysis (a red rectangle, measures 4 mm in width and 5 mm in height): (a) a snapshot from a polarized-light cryomacroscopy movie (side view of the cuvette); (b) schematic illustration of the reconstructed geometric model; (c) top view of the cross section used for f𝜎 parametric estimation, where SC and SW represent virtual temperature sensors located on P0, at the center of the domain and at the CPA-wall interface, respectively, while Smax represents virtual stress sensor located on Pmax at the symmetry line; and (d) an FEA mesh for thermal-stress analysis using ABAQUS, highlighting the boundary conditions used for heat transfer formulation, where h is the overall heat transfer coefficient accounting for forced convection and radiation heat transfer on the outer walls of the cuvette, while hfree accounts solely for heat transfer by free convection. Note that the frame of reference starts 1 mm away from the wall, to avoid optical reflection effects around the fillet at the inner walls corner of the cuvette.
Table 1.
Material properties of the CPA (7.05M DMSO) and quartz cuvette used in this study.
Fig 4.
Schematic illustration of a plane polariscope.
Where is the light entering the birefringent specimen,
and
are the fast and slow components for light, respectively, as they pass through the specimen, and
is the observed light passing through the system.
Fig 5.
Thermal history of the environment and strategically selected points in the cuvette shown in Fig 3B.
The instances at which maximum first principal stress, σmax, and simulated normalized maximum light intensity, Imax, are highlighted according in Fig 6.
Fig 6.
Comparison of experimental data and simulated results for normalized light intensity and maximum principle stress.
(a) Experimentally measured light intensity history at Smax location (see Fig 3C), in comparison with the calculated maximum principal stress, σ1, history and the simulated light intensity at the same location. (b) Variation of light intensity with the distance from the center of the cuvette at 0.5 mm below the tip of the cavity (along the dotted line in the inset), at the instance when maximum light intensity is observed (t = 505 s).
Fig 7.
Color-coded comparison of experimental data and simulation results for the normalized gray-scale light intensity field.
The gray-scale compiled light intensity field from experimental data is color-coded, where red represents high intensity and blue represents low intensity. The simulated light intensity field is represented by black contour lines, where 1 represents maximum intensity. (a) The analyzer is oriented parallel to the centerline of the cuvette. (b) The analyzer is oriented perpendicular to the centerline of the cuvette. (c) The analyzer is oriented at 45° − mid-angle between Cases A and B. This comparison is related to the field strain that develops after cooling the chamber at a rate of 25°C/min from room temperature, and subsequent temperature hold at -125°C for 170 s.
Fig 8.
Principal stresses along representative paths of light.
Principal stresses along the representative paths of light from Fig 3 (a) P0 and (b) P1, where the arrows are proportional to the stress magnitude, while the color scheme corresponds to the relative orientation of the stress vector with respect to the path of light: blue represents a stress vector perpendicular to the path of light while red represents a stress vector parallel to it.