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CN-116330049-B - Method for machining high-precision inner side surface of grooving monochromatic crystal

CN116330049BCN 116330049 BCN116330049 BCN 116330049BCN-116330049-B

Abstract

The invention discloses a high-precision inner side surface machining method of a grooving monochromatic crystal, which comprises the steps of 1) placing the grooving monochromatic crystal into a trough, roughly grinding the inner side surface of the grooving monochromatic crystal by adopting a grinding head of a magnetic control grinding device, wherein the magnetic control grinding device comprises a magnetic control driving unit and the grinding head, 2) finely grinding the inner side surface treated in the step 1) by adopting the grinding head, 3) wet chemical etching and damage layer removal of the inner side surface treated in the step 2), 4) finely polishing the inner side surface treated in the step 3) by adopting the grinding head, 5) cleaning the inner side surface treated in the step 4) and then generating a soft hydration layer on the inner side surface, and 6) stress-relieving and polishing the inner side surface by adopting the grinding head after the grooving monochromatic crystal treated in the step 5) is cleaned. The method can better transfer away the heat generated at the interface during polishing to obtain a better surface structure, and is limited by the overlapping part of the first crystal and the second crystal of the grooving type crystal.

Inventors

  • HONG ZHEN
  • Diao qianshun
  • LI MING
  • LIU PENG
  • JIANG YONGCHENG
  • TAO YE
  • SHENG WEIFAN

Assignees

  • 中国科学院高能物理研究所

Dates

Publication Date
20260505
Application Date
20221212

Claims (7)

  1. 1. A method for processing a high-precision inner side surface of a grooving monochromatic crystal comprises the following steps: 1) The method comprises the steps of placing a grooving monochromatic crystal into a trough, and roughly grinding the inner side surface of the grooving monochromatic crystal by adopting a grinding head of a magnetic control grinding device, wherein the magnetic control grinding device comprises a magnetic control driving unit and the grinding head, the magnetic control driving unit is used for driving the grinding head, the magnetic control driving unit is positioned outside the trough, and the grinding head is positioned in the trough and a covering layer of the grinding head is contacted with the inner side surface; 2) Finely grinding the inner side surface treated in the step 1) by adopting the grinding head; 3) Wet chemical etching is carried out on the inner side surface treated in the step 2), and a damage layer is removed; 4) Adopting the grinding head to finely throw the inner side surface treated in the step 3); 5) After the inner side surface treated in the step 4) is cleaned, a soft hydration layer is generated on the inner side surface; 6) After the grooving monochromatic crystal treated in the step 5) is cleaned, the grinding head is adopted to carry out stress relief polishing on the inner side surface; the material of the covering layer on the grinding head in the rough grinding stage is the same as the material of the grooving monochromatic crystal, the material of the covering layer in the finish grinding stage and the material of the covering layer in the finish polishing stage are polyurethane materials, and the material of the covering layer in the stress relieving polishing stage is foamed rubber material; placing the grooved monocrystals in alkaline chemical liquid and keeping constant temperature to form a soft hydration layer on the inner side surface.
  2. 2. The method of claim 1, wherein the cover layer hardness of the rough grinding stage > the cover layer hardness of the finish polishing stage > the cover layer hardness of the stress relief polishing stage, wherein the abrasive grain size in the grinding liquid of the rough grinding stage > the abrasive grain size in the grinding liquid of the finish polishing stage, and wherein no abrasive grains are added to the abrasive grain in the grinding liquid of the stress relief polishing stage.
  3. 3. The method according to claim 1 or 2, wherein the grinding liquid in the trough is alumina solution with the particle size of 10 μm in the rough grinding stage, stirring is kept during the processing, the rotating speed of the grinding head is 220rpm, and the interface pressure value between the grinding head and the inner side surface is 22kPa.
  4. 4. The method according to claim 1 or 2, wherein the grinding liquid in the trough is alumina suspension with the particle size of 3 μm in the finish grinding stage, the PH of the grinding liquid is=10, the rotating speed of the grinding head is 250rpm, and the interface pressure between the grinding head and the inner side surface is 12.7kPa.
  5. 5. The method according to claim 1 or 2, wherein the polishing liquid in the trough is a silica suspension with the particle size of 50nm in the fine polishing stage, the PH of the polishing liquid is 11, the rotating speed of the grinding head is 350rpm, and the interface pressure between the grinding head and the inner side surface is 6.3kPa.
  6. 6. The method according to claim 1, wherein the grooved monocrystals are placed in an alkaline chemical solution having ph=13, the chemical components of which are KOH and NH 2 OH, for 48 hours and kept at a constant temperature of 30 ℃.
  7. 7. The method of claim 1 or 2, wherein the slurry in the trough is deionized water during the stress relief polishing stage, the rotational speed of the grinding head is 200rpm, and the interface pressure between the grinding head and the inner side is 1.4kPa.

Description

Method for machining high-precision inner side surface of grooving monochromatic crystal Technical Field The invention belongs to the technical field of synchronous radiation, and relates to a method for processing the inner side of a grooving (Channel-cut) monocrystals. Background Synchrotron radiation is electromagnetic radiation emitted in the tangential direction of a track when a high-speed moving charged particle (the speed is close to the speed of light) makes a curvilinear motion. Synchrotron radiation is an excellent X-ray source and has many advantages such as wide and continuously tunable spectrum, high intensity, high brightness, high collimation, etc., and a monochromatic crystal is a core spectroscopic element in a synchrotron radiation device, also called the heart of a beam line. The grooving crystal is characterized in that a whole crystal is cut into specific grooves according to different requirements, the side surfaces of the two grooves are used as diffraction surfaces, compared with a double-crystal monochromator (Double Crystals Monochromator, DCM) fixed at a high position, the grooving crystal monochromator (Channel-cut Crystals Monochromator, CCM) has good light spot stability, as shown in fig. 1 and table 1, the light spot position change quantity of the grooving crystal monochromator is only 1/5000 of the former under the set initial condition, and meanwhile, the clamping mechanical structure required by the grooving crystal is very simple and has higher reliability. Table 1 shows the comparison of CCM and DCM spot position stability under specific conditions For diffraction crystals, it is desirable to ensure that the crystal lattice has as high a perfection as possible, and when the diffraction crystal plane states (stress residual, plane shape, roughness, etc.) are the same, the notch crystals have not only excellent spot position stability but also higher energy resolution than two flat crystals. However, due to the limitation of the processing technology, the grooved crystal is difficult to obtain the inner side surface with high surface precision and no stress residue, and the application range of the grooved crystal is greatly limited Currently, the international research on the notch crystal polishing process is mainly conducted by APS in the united states, university of osaka in japan and Sring-8. The mechanical and chemical polishing of the Z-shaped crystal is carried out by Ruben Khachatryan et al of APS to obtain a crystal surface with higher precision, but obvious scratches still exist on the processed crystal surface, and the mechanical and chemical polishing of the channel-cut type crystal is carried out by ELINA KASMAN et al by utilizing a thin-layer millstone which can be deep into a narrow and narrow groove space, however, the surface roughness of the obtained crystal can be only as the stress deformation of the thin-layer millstone(Sa) @1.66 x 1.66mm 2, with poor planarity, even up to 20 μm (PV) @130mm (three coordinate line measurement), reference ：Khachatryan R,Tkachuk A,Chu Y S,et al.Open-faced Z-shaped channel-cut X-ray monochromator[J].Proceedings of SPIE-The International Society for Optical Engineering,2004,5537;Khounsary A M,Macdonald C A,Kasman E,et al.SPIE Proceedings[SPIE SPIE Optical Engineering+Applications-San Diego,California,United States(Sunday 9August 2015)]Advances in Laboratory-based X-Ray Sources,Optics,and Applications IV-The best of both worlds:automated CMP polishing of channel-cut monochromators[J].2015;Kasman,Elina,Montgomery,et al.Strain-free polished channel-cut crystal monochromators:a new approach and results[C],2017. Takashi Hirano et al, university of Osaka and Spring-8, studied the channel-cut processing technology in 2016 by using a plasma chemical evaporation method (PCVM), and the surface roughness of the fused cast crystal obtained by the method can reach 0.535nm (Sa) @71 x 53 μm 2, the flatness is less than 200nm (PV) @71 x 53 μm 2, and the processed sample morphology photo has no scratches and no dead spots, but the processing technology has great limitation, and the overlapping size of the first and second crystals and the cutting slot distance are greatly limited because the technology needs to rotate the electrode to penetrate into the cutting slot, and the slot width mentioned in the literature also reaches 30mm, so that the application range of energy is greatly limited. The Takashi Hirano et al processed crystals of a more compact size using the same process in 2018, but the overlapping dimensions of the first and second crystals of the processed kerf crystals were only 5mm, and there was still a case where the overlapping portions were difficult to process (reference ：Hirano T,Osaka T,Sano Y,et al.Development of speckle-free channel-cut crystal optics using plasma chemical vaporization machining for coherent x-ray applications[J].Review of Scientific Instruments,2016,87(6):063118;Katayama T,Hirano T,Morioka Y,et al.X