SU1645921A1 - Antireflection coating for two wave lengths - Google Patents

Abstract

The invention relates to optical instrumentation and can be used to brighten the optical elements of excimer lasers, lighting systems of large-aperture lenses operating simultaneously in the ultraviolet and visible spectral regions. The invention provides a reflection coefficient of R 0.8% in the ultraviolet and visible regions of the spectrum for wavelengths associated with a ratio of 2.2 A2 / Ai 3.3 for optical elements with a refractive index of 1.45-2.2. The coating is made of two layers in the form of alternating quarter-wave layers with respect to AO layers, where AO, the first of which, adjoining Ai + A2 to the substrate, has a refractive index of PB 1.38 ± 0.01, and the second mon 1.34 ± 0.01. Zil. fe

Description

The invention relates to optical instrument making and can be used to brighten the optical elements of excimer lasers, illuminating systems of objects with large apertures, operating simultaneously in the ultraviolet and visible spectral regions.

The aim of the invention is to provide a reflection coefficient R of 0.8% in the ultraviolet and visible regions of the spectrum for wavelengths associated

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ratio 2.2 t - 3.3 for optical elements with a refractive index of p-1, 45-2.2.

FIG. Figure 1 shows the spectral reflection curves of a coating made on the basis of cryolite and lithium fluoride, obtained experimentally on glasses with refractive indices n 1.52 (curve 1), n - 1.62 (curve 2), n 1.8 (curve 3 );

in fig. 2 — reflection curves based on magnesium fluoride and cryolite obtained on glasses with refractive indices n — 1.52 (curve 1), n 1.62 (curve 2), and n 1.8 (curve 3); in fig. 3 shows the spectral reflection curves for different angles of incidence of the radiation.

The implementation of the coating was carried out by vacuum sputtering on an A700Q unit from Leibold Heraens, equipped with a non-oil pumping system like Turbovac 1500, with precise photometric control OMS - 2000 complete with an operation range extender (deuterium lamp, photomultiplier, interference filter kit for the UV spectrum).

The control of the optical thickness of the layers during the deposition was carried out on a control sample using OHS-2000

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recording the change in the magnitude of the reflected signal.

The control sample is a plane-parallel plate, polished on one side with a diameter of 42 mm, a thickness of 2 mm made of K8 glass with a refractive index of 1.52. The substrate was preheated to T 300 ° C for 2 h. A 6 kW power with two four-position crucibles was used as evaporators. Fluorides were evaporated by an electron beam defocused by the size of the crucible cell. The emission current is 20-50 mA, the deposition rate is 4-5 A / s. Each layer was monitored by its own control glass Witness.

In one embodiment of the manufacture of the coating, cryolite was used as a layer bordering the substrate, and lithium fluoride was used as the second layer. The coatings were applied to substrates of various glass grades with a refractive index of 1.45 - 2.2.

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Claims (1)

In another embodiment, magnesium fluoride was used as the first layer adjacent to the substrate, and cryolite was used as the second layer bordering the air. The invention Enlightenment coating for two wavelengths, made in the form of alternating quarter-wave relative to the layers, with high PV and low Mon indicators  2 L2 A2 refraction, where Before - I, Ai + A2 and Azchdliny waves on which the reflection is minimal, and the substrate with a high refractive index layer, characterized in that, in order to provide a reflection coefficient R S 0.8% in the ultraviolet and visible spectral regions for wavelengths associated Jtn    for optical ratio 2.2 3.3 Ai elements with a refractive index of 1.45 - 2.2, the coating is made of two-layer, moreover, np 1.38 - 0.01, pn 1.34 ± 0.01. t sh 500 600 700 FIG. one MO L9tsn 200 Sh 500 600 FIG. 2 7Yu 600 L, PP 600 700 Fig.Z 800 L, n