Fig. 1. (A) A diagrammatic view of the setup used to measure the spectral properties of the polarization reflection and to obtain images for imaging polarimetry. OF, optic fiber; CB, the attached film camera body; PL, linear polarizer; P, preparation; TT, tilting table as described by Denton and Nicol (Denton and Nicol, 1965); WT, water tank; L1, first illumination setting (Position 1); L2, second illumination position (Position 2); SP, spectrometer. (B) Geometry of the setup. The arrows marked L1 and L2 indicate the two illumination directions (at 90° and 45° to the observation axis, respectively). The dotted lines illustrate how the e-vector angles (which fall in the xy plane) were defined in terms of the x- and y-axes. All rotations of the tilting table were made about the y-axis. Thus, when the arm was perpendicular to the y-axis (i.e. it extended along the x-axis), changes in angle caused the arm to tilt upwards towards the light. When the arm axis was parallel to the y-axis, changes in angle produced rotation of the arm.