Birefringent Crystal - An Overview
Birefringent Crystal - An Overview
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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。
The polarization dependence of your refractive index may have many different consequences, many of that are really significant in nonlinear optics and laser technology:
As pointed out over, mild which is doubly refracted by anisotropic crystals is polarized with the electric vector vibration Instructions from the standard and extraordinary light waves getting oriented perpendicular to each other. The actions of anisotropic crystals under crossed polarized illumination in an optical microscope can now be examined.
Birefringence is formally described given that the double refraction of light in the transparent, molecularly requested content, that is manifested by the existence of orientation-dependent distinctions in refractive index. Several transparent solids are optically isotropic, meaning that the index of refraction is equivalent in all directions throughout the crystalline lattice.
Birefringence would be the assets of some transparent optical elements which the refractive index is dependent upon the polarization route - which can be outlined as the course of the electrical discipline.
In laser engineering and nonlinear optics, the phenomenon of birefringence takes place primarily within the context of non-isotropic crystals:
For bulk optical supplies, Additionally it is prevalent to take into account the real difference of refractive indices for The 2 polarization directions. The bigger that big difference, the larger the acquired retardance per millimeter of propagation size.
即使是各向同性介质，也会由于存在不均匀的机械应力而产生双折射。这可以在两个交叉偏振器间放置一块有机玻璃观察：当施加应力到有机玻璃上，可以看到由于应力诱导的与波长相关的双折射效应而产生的彩色图像。
Non-polarized white mild in the illuminator enters the polarizer on the left and is also linearly polarized using an orientation inside the direction indicated via the arrow (adjacent to your polarizer label), and is also arbitrarily represented by a red sinusoidal gentle wave. Up coming, the polarized light-weight enters the anisotropic crystal (mounted within the microscope phase) the place it's refracted and divided into two different parts vibrating parallel towards the crystallographic axes and perpendicular to one another (the pink open and loaded mild waves).
Pressure and strain birefringence come about as a result of external forces and/or deformation acting on materials that aren't In a natural way birefringent. Examples are stretched films and fibers, deformed glass and plastic lenses, and pressured polymer castings.
However, the slowest wavefronts come about once the wave travels together the brief axis of your ellipsoid. This axis is termed the slow axis. Concerning both of these extremes, wavefronts touring in other Instructions practical experience a gradient of refractive index, which can be dependent upon orientation, and propagate with velocities of intermediate values.
当光束在双折射晶体表面发生折射是，折射角与偏振方向有关。这样非偏振光束在非垂直入射到材料中的情况下分为两个线性偏振的光（双折射）。当非偏振光射向一个物体，如果采用双折射晶体看该物体，会出现两个像。
Anisotropic crystals, like quartz, calcite, and tourmaline, have crystallographically unique axes and communicate with light-weight by a system that is certainly dependent on the orientation of your crystalline lattice with respect for the incident gentle angle. When light-weight enters the optical axis of anisotropic crystals, it behaves in a method much like the conversation with isotropic crystals, and passes via at just one velocity.
In other scenarios, application of a solid electrical field has identical results, e.g. in Eyeglasses. The momentary application of this kind of area may even result in a frozen-in polarization, which implies which the induced birefringence stays even just after taking away the external area.
If the electrical industry has the direction in the optical axis, just one obtains the incredible index . This is possible only if the propagation path (a lot more exactly, the course on the check here vector) is perpendicular to your optical axis. For one other polarization course, just one then obtains the regular index .