The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal
The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal belongs to crystalline material preparation, particularly the seed crystal treatment process in the crystal growth.
The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal, the growth of many functional crystals industrialization day by day.Increase the crystalline size, can reduce its production cost, enlarge its range of application.But most crystalline anisotropy is obvious, if seed crystal depart from crystallographic axes to, then crystal the growth one segment length after, just asymmetric growth can occur, on one side toward foreign minister's (being referred to as " long pin "), the other side takes in, develop into situation about pulling gradually, influence the crystalline size.If seed crystal centering is better, will reduce the probability of asymmetric growth.
For example in the growth of large size yttrium vanadate crystal, axially bigger if seed crystal departs from c, then after one section of the crystal growth, crystal may have grown into the shape of " peaked cap ", makes the crystalline availability reduce greatly.In crystal growths such as YCOB, GdCOB, BBO, LBO, there is similar situation equally.These examples have all illustrated the importance of seed crystal centering.
Traditional seed crystal centering method is to utilize a paper that is decorated with the circle of the similar size of seed crystal head, by visual inspection and manual regulation, guarantees that seed crystal head when rotating is at circle inside-paint arc, reaches the purpose of centering seed crystal.The limitation of this way is the direct viewing that only relies on naked eyes, even experienced operator also have the error of 1-2 degree, may reach the 4-5 degree in the ordinary course of things, especially when the length of seed crystal is short.
The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal, its purpose is to use character such as laser direction is good, brightness height, and departing from of seed crystal direction amplified, corrects, and departs from thereby reach to proofread and correct, and improves the precision of seed crystal centering.
The present invention requires to place the direction of growth of the seed crystal (1) on the seed crystal stalk (2) that cleavage surface is preferably arranged, and for the crystal that does not have direction of growth cleavage surface, requires seed crystal (1) head is polished, and makes it can reflect He-Ne laser (4) preferably.Specifically, exactly He-Ne light (4) is shone seed crystal (1) head by speculum (3), through the light of head reflection again through speculum (3) reflection, its hot spot (5) a certain position that falls on the wall.
If when rotating seed crystal, flare will remain in certain scope.We judge the precision of seed crystal (1) centering according to the size of this scope and seed crystal (1) distance from wall (5).Theoretically, if guarantee the seed crystal flare 5 meters to go up the picture radius with reference to wall (5) be 10 centimetres circular arc, the direction that seed crystal (1) then is described departs from and is controlled in 15 minutes.
The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal, the synoptic diagram of the laser alignment method of seed crystal when accompanying drawing is the top-seeded solution growth crystal growth, wherein: (1) is seed crystal; (2) be seed rod; (3) be speculum; (4) be the He-Ne laser beam; (5) be with reference to wall.
The laser alignment method of seed crystal during with the top-seeded solution growth growing crystal, this invention can be applied to the seed crystal centering of most crystal growths.
Be example with centering a axle yttrium vanadate crystal seed crystal now, laser seed crystal centering comprises following step:
1. earlier seed crystal (1) head is artificially broken out a cleavage surface, in the seed rod (2) of packing into then, and seed rod (2) and single crystal growing furnace connected;
2. speculum (3) is placed on the correct position of seed rod (2) bottom, makes it can reflect He-Ne light (4) at a distance;
3. He-Ne light (4) is shone on seed crystal (1) head by speculum (3), reflex on the wall through speculum (3), the correct position of hot spot can be realized by rotating speculum (3);
4. rotate also and adjust seed rod (2) every now and then, make with reference to the picture of the hot spot on the wall (5) arc not exceed desired scope, seed crystal (1) has finished with regard to centering like this;