SU561924A1 - Optical device - Google Patents

Description

one

The invention relates to optical instrument making, and more specifically, to optical elements of devices and can be used for systems operating in narrow spectral regions used in quantum electronics, spectroscopy, space research, etc.

Optical systems operating in a relatively narrow spectral range are known, containing optical elements, e.g., lenses, probes, etc., whose reflectance of the outer surfaces at the working wavelength o should be close to zero. In other words, the surfaces of these optical elements must be coated for Ho.

Typically, surfaces are coated with a thin layer coating consisting of dielectric films. A decrease in the reflection at the interface between the surface of the substrate (optical part) and the air is achieved by choosing a coating, that is, by choosing the number of films, their thicknesses and refractive indices.

The known constructions of antireflection coatings consist of films whose optical thicknesses are multiples of a quarter of the wavelength located in the middle of the spectral range within which the reflection coefficient (1.2) is reduced.

These thin coatings reduce the reflection coefficients R in a given wavelength range, for example, in the visible part of the spectrum, to values of 5-1.0%. However, the region where such relatively low R values are achieved is not well. The ratio of the wavelength, which characterizes the upper boundary of the zone of enlightenment, to the wavelength, which characterizes the lower boundary, does not exceed 1.5-2.0. Outside such a region, the amount of R of the coating sometimes exceeds very substantially the reflection from a clean substrate.

Optical devices are known that comprise a substrate coated with a thin-layer coating consisting of dielectric films with a reflection coefficient close to zero for the operating wavelength io. Such devices include, first of all, constructions with a two-layer antireflection coating (3).

A significant disadvantage of two-layer antireflection coatings, as well as any other thin-layer structures intended to produce / (o), is that they do not allow a low reflection coefficient to be obtained for an arbitrary given wavelength K, especially if it differs from Lo more than 2 times.

Claims (3)

To obtain a reflection coefficient close to zero for another given wavelength i, while maintaining the original parameters when .to the proposed device comprising a substrate coated with a thin-layer coating consisting of dielectric films with a reflection coefficient close to zero for the working wavelength Ho , an additional interference system was introduced, having a reflection coefficient close to zero at the Lo wavelength, and a dielectric layer is located between the thin-layer coating and the additional interference system a, transparent in Co and K, the thickness of which in total with path differences caused by phase jumps at its boundaries is a multiple of 0.5 X. The drawing shows a section of the proposed optical device consisting of a substrate 1, a thin layer coating 2, a dielectric layer 3 and an additional interference system 4. The device is a substrate 1 on which a thin layer coating 2 of dielectric films is located. The refractive index n of the substrate 1 is / g ° for the wavelength l0 and nn. Thin-layer coating 2 consists of alternating films with high n ° c and pa and LOW n ° C and refractive index for Y0 and K, respectively. The design of the coating 2 (i.e., the number and thickness of the films entering it, as well as the substances forming them) are chosen in such a way that its reflection coefficient Ri (Ko) 0 FOR the beam falling from the medium has a refractive index of the same as the refractive index of the dielectric layer 3. Claims of the invention An optical device comprising a substrate with a deposited thin-layer coating consisting of films of dielectrics with a reflection coefficient close to zero for an operating wavelength K, characterized in that and close to zero for another given wavelength //, while maintaining the optical parameters at Ko, an additional interference system is introduced, having a reflection coefficient close to zero at the Ko wavelength, and a transparent dielectric layer is placed between the thin-walled coating and the additional interference system at Ko and K, the thickness of which in sum with the path differences caused by phase jumps at its boundaries is a multiple of 0.5 //. Sources of information taken into account at the examination: 1.US Patent JMb 3176575, cl. 88-1, 1965 2. The patent of England No. 932849, cl. S23c, 1958 3.I. V. Grebenshchikov et al., “Enlightenment of Optics, M.-L. Tostekhizdat, pp. 71-77, 1946 (prototype). :