Disc-shaped MgF2 crystal filming material and production method thereof

Abstract

The invention relates to the field of optical filming materials, particularly to a disc-shaped MgF2 crystal filming material and a production method thereof. The disc-shaped MgF2 crystal filming material is characterized in that the material is a colorless and transparent polycrystal optical crystal; at the position that the wave length is 500 mm, the refractive index Ne is equal to 1.38, and the material density is about 3.17 g / cm<3>, the material is designed and processed to be disc-shaped, conical or cylindrical, and the diameter and depth of the material are applicable to crucibles or crucible linings of electronic guns with various specifications, wherein the diameter ranges 20mm to 56 mm, and the thickness ranges between 5mm to 30 mm. Compared with the prior art, the disc-shaped MgF2 crystal filming material has the following benefits: the size requirement for MgF2-plated crucible of the electronic gun is fully met; material feeding and taking are very convenient; excellent evaporation characteristics of no splashing, no point collapsing, no gas discharging, and a flat evaporation surface are provided; the surface smoothness of a to-be-plated optical element is effectively improved; the disc-shaped MgF2 crystal filming material is particularly suitable for surface coating of super-smooth optical elements needing higher filming requirements.

Description

technical field [0001] The invention relates to the field of optical coating materials, in particular to a disc-shaped magnesium fluoride MgF 2 Crystal coating material and production method thereof. Background technique [0002] MgF 2 Splash and collapse in vacuum coating will seriously affect the smoothness of the coated optical surface, which has always been a worldwide problem that is difficult to solve completely. In the late 1980s, the United Kingdom and Germany successively prepared white powder MgF through advanced synthesis and purification methods. 2 , with a chemical purity of 99.99%, basically solves the MgF 2 Severe splashing and collapse of the coating, but this powdery MgF 2 It is only suitable for resistive evaporation in vacuum coating, not for electron gun coating. [0003] In 1997, China Changchun Institute of Optics and Mechanics developed "granular MgF" through vacuum sintering method. 2 "Crystal coating material", its quality is at the internation...

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Problems solved by technology

[0007] The widely used "granular MgF 2 The vacuum sintering method of "crystal coating material", because the large crucible adopts the internal heating method, the crucible is seriously unbalanced in heating, and it cannot be made into qualified MgF 2 rod crystal

[0008] The method of making crystals in a general-purpose descending single crystal furnace can sinter MgF in a rod-hole crucible. 2 Rod crystal, and it is single crystal, but because the furnace body is limited by the constant temperature zone and the pull-down mechanism, the crucible is not large, generally with a diameter of Ф300mm and a height of about 350mm. The sintered MgF 2 The number and length of rod crystals are limited, and their weight does not exceed 20 kg at best, and it takes a long time, consumes a lot of electricity, and is expensive. If it is processed into a disc-shaped MgF 2 The crystal price will exceed 5,000 yuan per kilogram, so it can only be used for optical components and cannot be used for vacuum coating at all

It is these reasons that cause the "disc-shaped MgF 2 "Crystal coating material" has not been available and applied so far

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