positive birefringence

positive birefringence

[′päz·əd·iv ‚bi·ri′frin·jəns]
(optics)
Birefringence in which the velocity of the ordinary ray is greater than that of the extraordinary ray.
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In addition, Inoue noted the reversal of contrast when orienting the spindle axis more perpendicular to the slow axis of the compensator, an observation that unambiguously assigned a positive birefringence to the material that formed the spindle.
Under polarized light, the calcified deposits show weekly positive birefringence suggestive of CPPD ((c) low-power view, (d) high-power view).
Therefore, the sign for the stress-optical coefficient [C.sub.[sigma]] of PS results in the sign reversal in the birefringence in the PS skin layers compared with the PC core layer showing the positive birefringence due to positive values of [C.sub.[sigma]] of PC in the melt and glassy states.
The difference in areas of the negative and positive birefringence increases with an increase of the initial temperature.
The lesion showed rhomboid-shaped and blunt-ended crystals (black arrows) with weak positive birefringence under polarizing microscope in the sections stained with the Shidham method (Figure 2, D and H).
Calcium pyrophosphate dihydrate (CPPD) crystals show the diagnostic positive birefringence (Figure 2, D and H) observed in this lesion.[2] They are associated with crystal deposition disease, called chondrocalcinosis articularis.
The extension axis of the positive birefringence is taken to be the X-axis (machine direction) and that of negative birefringence was the Y-axis (transverse direction).
As the egg floats up, the fertilization envelope rises and its positive birefringence increases over the next 3 to 4 mm.
Our proposal for the "low-orientation-induced birefringence materials" is the completely unique system in which the special "cardo" structure of fluorene groups in FBP molecules plays an important role in compensating the positive birefringence induced by the orientation of PEN molecules as demonstrated in Fig.
This is because the orientational positive birefringence of PEN is compensated by the negative birefringence induced in FBP molecules because of the special molecular structure involving the "cardo structure" due to the fluorene groups in FBP.
The poles of the asters are then separated over the next 15 to 20 minutes by a growing meiotic spindle, which exhibits prominent positive birefringence in the middle of the clear zone [ILLUSTRATION FOR FIGURE 1, C, D OMITTED].
This is due to the increasing positive birefringence, as mentioned before.
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