What Does Birefringent Crystal Mean?
What Does Birefringent Crystal Mean?
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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。
In Just about every frame of Figure eight, the axis of your microscope polarizer is indicated via the cash letter P which is oriented within an East-West (horizontal) route. The axis of the microscope analyzer is indicated by the letter A and is particularly oriented in the North-South (vertical) direction. These axes are perpendicular to one another and end in a totally dim subject when observed through the eyepieces without having specimen over the microscope stage.
直光纤只有很小的随机双折射，即使这样其中的光传输一段距离后偏振状态也会发生变化。存在保偏光纤，是利用了很强的双折射来抑制这些效应。
In other instances, birefringence can be induced in originally isotropic optical materials (e.g. crystals with cubic construction, glasses or polymers) may become anisotropic as a consequence of the application of some exterior impact which breaks the symmetry:
Mainly because one particular wave is retarded with regard to the opposite, interference (possibly constructive or destructive) takes place in between the waves as they pass through the analyzer. The web result is that some birefringent samples get a spectrum of color when observed in white mild via crossed polarizers.
类似的，激光光束在存在热效应诱导的双折射效应的激光器晶体中传输时，偏振态也发生变化。这一变化与位置有关，因为双折射轴方向是变化的（例如，通常是轴向变化）。这一变化（与激光器谐振腔中的偏振光元件结合）是去极化损耗的来源。
is usually also utilized to be a amount (see beneath), ordinarily outlined because the distinction between extraordinary and standard refractive index at a certain optical wavelength.
, as well as the refractive index for specified wavelength is determined by the relative orientation of electric powered field director and optical axis:
This is certainly the most typical way of period matching for different varieties of nonlinear frequency conversion including frequency doubling and optical parametric oscillation.
Stress and pressure birefringence come about as a result of external forces and/or deformation acting on products that aren't By natural means birefringent. Examples are stretched movies and fibers, deformed glass and plastic lenses, and pressured polymer castings.
Figure eight(a) illustrates the anisotropic tetragonal, birefringent crystal within an orientation the place the very long (optical) axis of the crystal lies parallel to your transmission azimuth of your polarizer. In such cases, light passing from the polarizer, and subsequently in the crystal, is vibrating inside of a aircraft that may be parallel to the path with the polarizer. Because Not one of the light-weight incident on the crystal is refracted into divergent normal and extraordinary waves, the isotropic light waves passing with the crystal fail to supply electrical vector vibrations in the correct orientation to traverse through the analyzer and generate interference consequences (begin to see the horizontal arrow in Determine 8(a), as well as discussion below).
The vectorial romance defining the interaction among a light-weight wave in addition to a crystal by which it passes is governed through the inherent orientation of lattice electrical vectors plus the way of the wave's electric vector element. Therefore, a cautious consideration in the electrical Houses of the anisotropic substance is essential for the understanding of how a click here light wave interacts with the material as it propagates via.
Several microscope suppliers make the most of this sensitivity by supplying a complete-wave retardation plate or very first-purchase red compensator with their polarizing microscopes to assist experts in figuring out the Homes of birefringent elements.
In Determine three, the incident gentle rays supplying increase to the everyday and extraordinary rays enter the crystal inside a route that is definitely oblique with regard into the optical axis, and they are responsible for the observed birefringent character. The behavior of the anisotropic crystal differs, having said that, if the incident light-weight enters the crystal in a way that is definitely either parallel or perpendicular for the optical axis, as presented in Figure four. When an incident ray enters the crystal perpendicular into the optical axis, it is actually divided into everyday and incredible rays, as described earlier mentioned, but as an alternative to taking distinct pathways, the trajectories of such rays are coincident.
在激光器技术和非线性光学中，双折射现象通常发生在非各向同性晶体中：