Ar coating

 

(57) Abstract:

Usage: in an optical instrument for enlightenment parts. The inventive antireflective coating consists of alternating layers, the first and third of which are made with high refractive index, and the second and fourth low refractive index and optical thickness of the layers counting from the substrate, is treated as 10 : 6 : 4 : 1, and adjacent to the substrate layer has an optical thickness 0,163oin this case nin= 2,28 - 2,39; nn= 1,35 - 1,51;o= 10600 mm 1 Il.

The invention relates to the technology of optical coatings and can be used in an optical instrument for enlightenment parts.

Known ar coating [1] consisting of five layers of alternating high and low refractive indices, the optical thickness of which is connected by the relation 1,78:0,25:0,23:1,08:0,92, and adjacent to the substrate layer has an optical thickness 0,4450where0the wavelength corresponding to the middle of the range enlightenment.

The closest technical solution to offer is the ar coating for optical elements [2] consisting of four dielectric, W is C substance with a high refractive index, and optical thickness connected by the relation

2nind12nnd22nind3nind40,250< / BR>
However, the known coating can only be used for optical elements made from a material with a refractive index of 1.45 to 1.8.

Object of the invention is robust and resistant to laser radiation antireflection coating, providing the transmission of 95-97% in the spectral range of 8-12 μm, for optical elements with refractive index of 2.2 and 2.7.

The problem is solved due to the fact that in the antireflection coating consisting of alternating layers, the first and third of which are made with high ninrefractive index, and the second and fourth low-nnthe refractive index. The optical thickness of the layers counting from the substrate, is treated as 10:6:4:1, and adjacent to the substrate layer has an optical thickness 0,163 0while nin2,28-2,39; nn1,35--1,51;0= 10600 nm.

Set out the essential features, namely, the optical thickness of the layers linked by a ratio of 10:6:4:1 and adjacent to the substrate layer, equal 0,163 0provide the coating with a total thickness of 0,3420optical is jku each component of the coating is divided into thinner layers, and its total thickness is slightly more than a quarter wavelength, which significantly reduces the stresses in the layers of coating.

The drawing shows a spectral transmittance curve measured on the X-29.

From the above specifications you can see that the ar coating effectively reduces reflected in a wide spectral range for optical elements used in optical instruments, in particular, thermal imaging devices.

The proposed floor has the "0" group strength abrasion.

The coating is applied by thermal or electron beam evaporation in a vacuum ion-beam-assist vacuum installing WU-1A.

Make details of the optical materials: zinc sulphide, zinc selenide, cadmium telluride. For applying a layer with a high refractive index of ninuse zinc sulphide, and for applying a layer of low refractive index fluoride of yttrium.

The average transmittance enlightened optical components 10 mm thickness in range (0,8-1,2)104nm, measured on the X-29, shown in the table.

The table shows that the value of bandwidth is 95-97%

inrefractive index, and the second and fourth low-nnrefractive index, characterized in that the optical thickness of the layers counting from the substrate, is treated as 10 : 6 : 4 : 1, and adjacent to the substrate layer has an optical thickness 0,163 owhile nin= 2,28 - 2,39; nn= 1,35 - 1,51;o= 10600 nm.

 

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