slow ray

slow ray

[′slō ′rā]
(optics)
In crystal optics, that component of light in any birefringent crystal section which travels with the lesser velocity and has the higher index of refraction.
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References in periodicals archive ?
Figure 2, D and H are under polarized light with slow ray axes perpendicular to each other (direction of the slow ray axis is shown with white arrows with the letter S).
The crystals are blue when the long axis of the crystals is parallel to the axis of slow ray and yellow when their long axis is perpendicular to the axis of slow ray.
Some wavelengths are slowed down more than others.The combination of wavelengths that pass the upper polar produces interference colors, which depend on the retardation between the fast and slow rays.