(b) Photographs experimentally taken utilizing dynamic photoelasticity in conjunction with high-speed cinematography show the time-dependent isochromatic
fringe patterns (distributions of [[tau].sub.max]) generated near a free surface by supershear dip-slip rupture (V [congruent to] 1.73-1.98 [V.sub.s]) on a model fault plane (initially welded interface) between two identical transparent, birefringent linear elastic polycarbonate plates.
The orders of patterns of isochromatic
fringes generated in each region are shown in Table 2.
Shrinkage stress values ([[sigma].sub.0]) were obtained from the isochromatic
ring diameters using the following equation:
As the sample cooled down, the changing stress was measured by counting the isochromatics
(i.e., fringes) passing the centre of the aperture using the photographs.
Because of the use of white light, the isochromatic
fringe pattern appeared as a series of colored bands (Fig.
Thresholds that define red-green (RG) and blue-yellow (BY) sensitivity, within the neutral isochromatic
zone, are plotted as x, y chromaticity co-ordinates in the CIE chromaticity diagram (1931).
Figure 4 shows the isochromatic
patterns photographed for the model subjected to force [P.sub.H] applied in the same section as for the case presented in Fig.2.
Under polarized light, flow induced molecular anisotropy produces multiple retardation orders of the isochromatic
fringes, which are related to the birefrmngence as:
Colour confusions are specified in isochromatic
zones in the reference system approved by the Commission Internationale d'Eclairage (CIE) in 1931.
6 show the isochromatic
patterns photographed for the two investigated models subjected to compression and torsion respectively.
It has been shown that certain coloured filters change the chromaticity of the hues used in the Farnsworth D15 test in such a way that the set spans a greater number of isochromatic
lines, thus improving the discrimination of those hues.
Colour vision tests exploit isochromatic
zones and therefore a change in the spectral properties of the pigment can lead to colours falling away from the confusion lines or a change in the luminance, and the test can become invalid.