Birefringent Crystal Options
Birefringent Crystal Options
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各向异性透明晶体如方解石、石英等的折射率，是其固有的特性，称为永久双折射。
Clearly, the greater the thickness or change in refractive indices, the better the degree of retardation among waves. Early observations made over the mineral calcite indicated that thicker calcite crystals induced higher differences in splitting of the pictures viewed through the crystals, like Individuals illustrated in Determine 3. This observation agrees with the equation previously mentioned, which suggests retardation will improve with crystal (or sample) thickness.
For propagation alongside the optical axis, the electric industry can only be perpendicular to that axis, to make sure that a person obtains the common index for just about any polarization way. In that condition, no birefringence is seasoned.
If waves with diverse polarization Instructions propagate with each other in the waveguide, their section relation is restored just after integer multiples with the propagation beat length.
wherever n(e) and n(o) would be the refractive indices knowledgeable because of the incredible and normal rays, respectively. This expression holds real for almost any part or fragment of an anisotropic crystal except for gentle waves propagated together the optical axis of your crystal. As the refractive index values for every ingredient can vary, the absolute price of this difference can figure out the full amount of birefringence, though the indication of birefringence are going to be possibly a detrimental or constructive value.
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文献中，双折射通常包含两种不同的含义。经典光学中，就是下面所说的双折射（double refraction）。
光纤和其它波导中，采用有效折射率差值描述更好。这与传播常数虚部的差值直接相关。
For remarkable waves, where by the refractive index is dependent upon the angular orientation, there is a spatial wander-off: the path of ability propagation is marginally tilted versus that in the k vector.
Quantitative Investigation of the interference colours observed in birefringent samples is frequently accomplished by consulting a Michel-Levy chart much like the one particular illustrated in Determine 9. As is evident from this graph, the polarization colours visualized from the microscope and recorded onto movie or captured digitally is often correlated with the particular retardation, thickness, and birefringence of the specimen. The chart is relatively user friendly with birefringent samples if two with the a few required variables are recognized. When the specimen is placed in between crossed polarizers within the microscope and rotated to some situation of highest brightness with Anybody of various retardation plates, the color visualized inside the eyepieces could be traced about the retardation axis to discover the wavelength difference between the normal and extraordinary waves passing through the specimen.
The vectorial romantic relationship defining the conversation involving a lightweight wave and also a crystal through which it passes is ruled because of the inherent orientation of lattice electrical vectors and the path in the wave's electric vector component. As a result, a thorough consideration from the electrical Homes of the anisotropic substance is elementary into the knowledge of how a light wave interacts with the material because it propagates by means of.
Anisotropic crystals, for instance quartz, calcite, and tourmaline, have crystallographically distinctive axes and interact with mild by a system that's dependent upon the orientation in the crystalline lattice with respect to your incident light angle. When light enters the optical axis of anisotropic crystals, it behaves in the way comparable to the conversation with isotropic crystals, and passes as a result of at just one velocity.
Maybe The most spectacular demonstrations of double refraction takes place with calcium carbonate (calcite) crystals, as illustrated here in Determine two. The rhombohedral cleavage block of calcite produces two pictures when it's positioned in excess of an item, after which you can seen with mirrored gentle passing from the crystal. Amongst the images seems as would normally be envisioned when observing an item through clear glass or an isotropic crystal, while the other graphic seems a little displaced, resulting from the character of doubly-refracted gentle.
Each time a beam is refracted within the surface area of the birefringent crystal, the refraction angle will depend on the polarization route. An unpolarized light-weight beam can then be split into two linearly polarized beams when hitting surfaces of the material with non-normal incidence (