The interference coating
(57) Abstract:The coating consists of alternating layers with a low value of the refractive index of magnesium fluoride and high refractive index of a material which is transparent in the infrared region and having a refractive index of not less than 2.2 and compressive stresses in the layer. In the middle layer MgF2put a layer of silicon dioxide. Layer is 0.2 to 0.5 optical thickness of the layer MgF2due to a corresponding reduction in its thickness. Layers with high refractive index can be made of zinc sulfide or zinc selenide or sulphide of antimony, or arsenic sulfide or arsenic selenide. On the outer layer of a material with high refractive index can be applied to the protective half-wave layer of low refractive index. The protective layer consists of a quarter-wave layer MgF2with a layer of SiO2and a quarter-wave layer of SiO2. Ensures the long-wave expansion of the scope and improve performance. 2 C.p. f-crystals, 1 Il. The invention relates to the field of optical instrument, in particular to interference coatings and can be used to create sergentia, including laser technology in the field of wavelengths from 0.4 to 9.0 μm.Interference coatings are widely used in optical instruments including laser technology, providing the necessary optical and performance characteristics of optical components and systems. The most common (basic) design is a multi-layer coating of the type P (HB)nor P (HB)nwhere P is optically polished substrate, and N - alternating interference layers having relatively high and relatively low values of refractive index, respectively, n is the number of pairs of layers of type b and H.One of the known multilayer interference coatings used in the visible and near IR regions is the design of the form P (ZnS - NaAlF6)nZnS, where ZnS zinc sulfide having a transparency range of 0.4 - 14,0 μm and a refractive index of 2.5 to 2.2, respectively; NaAlF6- cryolite having a transparency range of 0.2 - 14,0 mm and a refractive index of 1.35 and 1.33 /1/. This coating has the following advantages: occurs in a wide region of wavelengths from 0.4 to 14.0 microns, these film-forming materials are relatively inexpensive and layers of them can be half the options are low moisture resistance, the corresponding group 3 and low mechanical abrasion, the corresponding 3 group OSTS-1901-85 /2/, i.e., the coating prevents rubbing optical cloth with an organic solvent. In this construction, the moisture resistance is determined mainly by the cryolite, and the mechanical strength of mainly zinc sulfide, located outside.With the development of vacuum technology for coating and related technology using electron beam evaporation (ELI) were obtained multilayer interference coatings based on refractory oxides /1/. The main advantages of such coatings are the best performance characteristics: high moisture resistance, abrasion resistance and radiation resistance. The main disadvantages of interference coatings of refractory oxides are not sufficiently far-field implementation (of 0.25 to 2.5 microns), and relatively high cost. Although the transparency of refractory oxides extends to 10 μm, for wavelengths of more than 2.5 μm multilayer coatings are mechanically unstable due to significant unbalanced mechanical stresses in the layers. The high cost of the coatings of logocreator consumable materials and the necessity of a more expensive vacuum installations equipped with ELI.Known for the design of multilayer interference coatings (prototype) of the form P (ZnS-MgF2)nZnS, where MgF2-magnesium fluoride has a refractive index of 1.46 - 1.38 in transparency 0,115 to 10.0 μm, respectively. Practical implementation of this design is limited to a short region border transparency ZnS i.e., 0.4 µm in wavelength from 1.0 to 1.35 μm. The latter is defined by the mechanical resistance of the multilayer coating due to unbalanced tensile stresses in the layers MgF2. Multilayer coatings of this type correspond to group 2, the moisture resistance and group 3 mechanical strength /2/. The main advantage of this design before the first analog is a higher moisture resistance. The main disadvantages of this design are: insufficient far-field implementation and insufficient mechanical strength.The aim of the invention is the extension of the working area in the long-wavelength direction and operational improvement at a low cost.This goal is achieved by the fact that in the middle layer MgF2put a layer of silicon dioxide (SiO2), SOS Additional outer layer In the deposited poluvalmovye layer N, consisting of a quarter-wave layer type MgF2- SiO2- MgF2with the same ratios in thickness and a quarter-wave layer of SiO2. Layers of type b can be made of materials such as zinc selenide (ZnSe), sulphide of antimony (Sb2S3), sulphide of arsenic (As2S3), arsenic selenide (As2Sl3) or other transparent in the infrared region of the SIP, with a refractive index of not less than 2.2 and compressive mechanical stress in the layers.In the drawing conditionally (in cross section) shows the design of the proposed interference coatings of the form P (HB)n2H, where: 1 - optically polished substrate, 2 - layers MgF2separated by a layer 3 of SiO2, 4 - ZnS layers, forming a periodic structure pattern mirrored finish with a number of pairs equal to n, on the outer layer of ZnS are quarter-wave layer MgF2- SiO2- MgF2and a quarter-wave layer of SiO2.The present invention has the following essential features: multilayer interference coating consisting of alternating between the layers with high () and low (N) values of the refractive index, where the material layer is ZnS, and the material layer H - MgF2put a layer of silicon dioxide of a thickness of 0.2-0.5) from the total optical thickness of the layer H, due to a corresponding reduction in the thickness of the MgF2. The use of SiO2as the interference layer known /1/, transparency is (from 0.2 to 9.0) μm, and the refractive index (1,55-1,45), respectively. It is known that layers of SiO2obtained by vacuum technology, are compressive stresses. Layers MgF2a thickness of more than 0.1 μm have considerable tension strains and already a quarter-wave layer at a wavelength of 4 μm on the glass substrate) is destroyed by cracking. For the prototype the full consideration of internal stress (compressive ZnS and stretching for MgF2) are not performed and there is an excess tensile stresses, however, does not lead to destruction of the coating in the region of 0.4-to 1.35 μm. For large wavelengths multilayer coatings of this type are destroyed by cracking very quickly. The introduction of a layer of SiO2in the middle of the interference layer MgF2can significantly reduce tensile stress in the layer H and thereby to realize the compensation of mechanical stresses in a multilayer structure, the latter becomes fur the puff SiO2(0,2-0,5) effective refractive index layer H becomes (1,4-1,42) respectively, which is quite acceptable for multilayer interference structures with the aim of preserving its optical characteristics. The introduction of a layer of SiO2it is in the middle layer MgF2allows you to avoid incompatibility layers of ZnS and SiO2and thereby prevent destruction of the coating due to the low cohesive strength between them.The specified region of the layer thicknesses of SiO2-(0,2-0,5)H chosen from considerations of providing mechanical stability of the interference coating as the visible and IR regions without a significant increase of the refractive index of the layer N. For the short-wave region, it is advisable to apply a layer of a thickness of 0.2-0.3) and longwave (5,0-9,0) μm, respectively (0.4 to 0.5), which is specified almost in the evaluation of the mechanical stability of multilayer coatings during thermal Cycling tests.The second additional outer layer In the deposited protective poluvalmovye layer H, consisting (from layer b) of a quarter-wave layer type MgF2- SiO2- MgF2with the same ratios in thickness, and a quarter-wave layer of SiO2. To increase poverhnostnogo layer To cause the protective poluvalmovye layer of SiO2. With the same purpose on top of the layer, we have introduced poluvalmovye protective layer, however, its composition meets the requirement of the necessary cohesive strength of the layer and to demand compensation of the stresses in a multilayer structure.The third layer may also be made of materials ZnSe, Sb2S3, As2S3, As2Se3or other transparent in the infrared region, having a refractive index higher than 2.2 and compressive mechanical stress in the layers. The above POM known in the literature as transparent in the infrared region. Similarly ZnS they have a compressive mechanical stress in the layers, and the values of their refractive index is superior to 2.2. With the aim of obtaining an optical or operational advantages over multilayer coatings with ZnS can be applied above the SIP.Describes the distinctive characteristics form a new set of features is not known in the patent and technical literature.The proposed solution is implemented in the following way. First determine theoretically or experimentally the parameters of a multilayer interference structure, i.e., determine the number and thickness of layers on the basis of the function is the second region of wavelengths on the basis of a design P/(MgF2- SiO2- MgF2) - ZnS/nor other SIP-type of the above. With regard to our recommendations experimentally clarify the required thickness of the layer of SiO2in the field of recommended values (0.2-0.5) H. If you need to have a high mechanical and radiation resistance, which is typical, for example, for laser mirrors, on top of the layer type, you must provide protective poluvalmovye layer consisting of a quarter-wave layer type MgF2- SiO2- MgF2and a quarter-wave layer of SiO2. Then produce a coating of vacuum technology using any method of controlling the thickness of layers in the coating process.Practically, we have produced a quarter-wave laser mirrors for wavelengths 0,633, 1.06 and 1.5 μm on the substrate made of quartz glass and glass K-8 with a reflectivity of from 90 to 99.5%. In particular, "deaf" mirror coating at the wavelength of 1.06 μm had the following design P/(0,33 MgF20,33 SiO20,33 MgF2) - ZnS/7(0,33 MgF20,33 SiO20,33 MgF2) SiO2. The coating was applied to the domestic vacuum installing WU-IA using photometric control of the thicknesses of layers during the coating process. Cover imeokparia allowed RUB optical cambric cloth with an organic solvent. Radiation strength of the coating were close to the mirrors of the refractory oxide-based materials, zirconium oxide (ZrO2and SiO2.In addition, there were experimental laser mirrors for wavelengths 3,39 and 5.5 μm on the substrate made of quartz glass KEY and zinc selenide coated with type P/(0,3 MgF20,4 SiO20,3 MgF2Sb2S3/2(0,3 MgF20,4 SiO20,3 MgF2) SiO2with a reflectivity of about 90%. In this case, as the layer used In the sulphide of antimony, which helped to reduce the number of layers in the mirror coating and thereby improve mechanical stability and to reduce cost. Moisture resistance and strength, wear coatings had the same characteristics as in the first case.Thus, a multilayer interference (mirror) coating in accordance with the proposed invention has allowed to expand the scope of at least 5.5 μm and improve operating characteristics compared to the prototype, as compared with analogues of refractory oxides to extend the scope of the implement in the direction of the infrared radiation and to gain an advantage in the cost of at least 2-4 times.
/P>2. The industry standard, OSTS-1901-85.3. P. P. Yakovlev, B. B. Sacks. Designing interference coatings. M.: Mashinostroenie, 1987. 1. The interference coating consisting of alternating between the layers with high and low values of refractive index, where the material layer with a low refractive index is magnesium fluoride (MgF2), characterized in that the layers with a high refractive index made of a material transparent in the infrared region and having a refractive index not less than 2.2 and compressive stresses in the layer and the middle layer MgF2put a layer of silicon dioxide (SiO2), component (0,2 - 0,5) optical thickness of the layer of low refractive index due to a corresponding reduction in the thickness of the layer MgF2.2. The floor under item 1, characterized in that the layers with a high refractive index is made of zinc sulfide or zinc selenide or sulphide of antimony, or arsenic sulfide or arsenic selenide.3. The floor under item 1 or 2, characterized in that the outer layer is made of a material with a high refractive index deposited protective poluvalmovye layer with a low refractive index, consisting start is on the layer of SiO2amounting to 0.2 to 0.5 optical thickness of this quarter-wave layer, and a quarter-wave layer of SiO2.
FIELD: optical engineering.
SUBSTANCE: at least two dielectric layers are produced with preset thickness. Layers are disposed one onto the other to form pack of layers. Thickness of layer packs is subject to reduction and thicknesses of separate layers are similarly reduced by means of deforming layer packs to keep relation of thicknesses or relation of thicknesses of layers. Layer pack is disposed between two carrying layers before subjecting the layers to deformation. At least one carrying layer is formed from several separate layers, which are supposed to be disposed subsequently at the end of process of partial deformation at any previous layer of carrying layer. Separate layers of carrying layer can be overlayed onto previous separate layers of carrying layer.
EFFECT: simplified process of manufacture; improved reflection factor.
FIELD: optical instrument engineering.
SUBSTANCE: invention can be used for wide-band light reflecting. Reflecting surface has dielectric layers A, B and C. A layer is made of material having low refractivity, B layer is made of material with average refractivity and C layer is made of material having high reflectivity. Optical thickness of layers equals to λr/4, where λr is wavelength of middle part of interval having high refractivity. Sequence of layer alternation looks like (CDCABA)KCBC, where K>=and has to be integer. Spectrum range with high reflectivity is widened due to shift in adjacent bandwidths at opposite sides along wavelength scale.
EFFECT: widened spectrum range with higher refractivity.
FIELD: optical engineering.
SUBSTANCE: device can be used for getting image from space, including surface of Earth, from space and from different sorts of air carriers. Device has at least one information channel which channel has objective, filter and multi-element receiver. Filter is made of two lenses, which lenses form flat-parallel plate. Lenses are made of the same material with equal radiuses of curvature of their spherical surfaces. Interference coatings are applied onto spherical surfaces, which coatings form, together with material of lenses, spectral range of device. Filter can be installed between objective and radiation receiver. In this case the first lens is made flat convex, the second one is flat concave. Center of radius of curvature of spherical surface of flat-convex lens is brought into coincidence with center of exit pupil of objective. Filter can be installed in front of objective.
EFFECT: constancy of borders of spectral sensitivity and of level of transmission within total area of angle of view; improved precision of measurement.
7 cl, 3 dwg
FIELD: optical instrument engineering.
SUBSTANCE: optical filtering device can be used for building devices for spectral filtration of optical images, for example, for wavelength re-tune optical filters, IR imagers working within specified narrow spectral ranges. Filtering device being capable of re-tuning within preset wavelength range is based upon interferometers. Interferometers are disposed along path of filtered radiation flow at different angles to axis of flow. Reflecting surfaces of plates of any interferometer, which plates are turned to meet one another, are optically polished and they don't have metal or interference mirror coatings. To filter selected wavelength of λm; the following distances among reflecting faces of interferometers: d1=(λm/2)k, k=1 or k=2, dn=(n-1)d1 or nd1. Filtering device is equipped with different filters which cutoff radiation outside borders of range to be filtered, including filters which are made of optical materials being transparent within band of spectral characteristic of sensitivity of consumer's receiver, which receiver registers filtered radiation. Filter cutting off short wavelength radiation is made of materials, which form border with positive derivative of dependence total internal reflection angle depending on wavelength. Filter cutting off long wavelength radiation is made of materials which form border with negative derivative of angle of total internal reflection depending on wavelength.
EFFECT: improved stability of parameters; increased transmission ability in maximal points of bands and reduction in number of transmission bands; increased relative aperture; higher quality of filtration; reduced number of side maximums.
4 cl, 5 dwg
FIELD: narrowband filtration covers.
SUBSTANCE: narrowband filtration cover contains two systems of alternating dielectric layers with different refraction coefficients and equal optical thickness λ0/4, in the form of high reflection mirrors, and a dielectric layer dividing them. In accordance to the invention, structure of high reflection mirrors additionally features dielectric layers with intermediate value of refraction coefficient and dividing layer has optical thickness λ0 or one divisible by it, and sequence of layer alternation has form (CBCABA)KD(ABACBC)K with nA<nB<nC, where refraction coefficient of dividing layer nD is not equal to nA (for example, nD=nC) and k≥1 is an integer number, where: λ0 - maximal filtration cover throughput wave length; A, B and C - dielectric layers with values of refraction coefficient nA, nB and nC respectively, and D - dividing layer.
EFFECT: increased selectivity due to expansion of high reflection bands on the sides of pass band.
FIELD: fiber-optic transmission systems.
SUBSTANCE: optical multilayer filter has N dielectric layers made of materials with different refractivity. Optical thickness of any layer equals to λ/4, where λ average wavelength of transmission band of optical filter. Optical multilayer filter is composed of input optical transformer, selective part and output optical transformer. Level of signal distortions is reduced till preset value for wide range of frequency characteristics of decay of filter within preset transmission band and decay is improved within delay band till preset value.
EFFECT: widened area of application.
FIELD: fibre-optic communication, optical multilayer filters.
SUBSTANCE: optical multilayer filter (OMLF) consists of an input optical transformer (In. OT 1), a selective part (SP 2), and output optical transformer (Out. OT 3) and substrates 5, 6. The In. OT 1, SP 2, and Out. OT 3 consist of NIn=2s, Nsp=4k and Nout=2r alternating layers 7 and 8, respectively, with high nh and low nl values of refractive indices of materials they are made of. The thickness of every layer d=0.25λ, where λ is the mean OMFL bandwidth wave length. Refractive indices of adjoining layers of the In OT and SP, and those of SP and Out.OT are equal. Note that the SP alternating layers are made from materials with refractive indices mirror-symmetric relative to the SP centre. The first layer of In. OT and the last layer of Out. OT are connected to substrates. Proposed are the relations to calculate the parameters of claimed arbitrary type OMLF.
EFFECT: reduction of signal distortion to preset magnitude in a wide frequency range of the filter attenuation in the preset bandwidth and increase in attenuation to the preset magnitude that allows wider application of the aforesaid filters.
3 cl, 7 dwg
SUBSTANCE: invention concerns area of optical thin-film coatings. The spectral divider contains the optical interference system with alternating quarter wave layers; part of them has an optical thickness not multiple to quarter of length of an emission wave. The spectral divider design allows obtaining the optimised spectral characteristics having small fluctuations of the transmittance factor in a working range of transparency.
EFFECT: spectral divider can be used at a direct and inclined light ray tilt angle in various geodetic devices and special purpose devices.
2 cl, 4 dwg
FIELD: physics, optics.
SUBSTANCE: tunable optical filter with Fabry-Perot interferometre has transparent plates with mirror coatings with spacing in between. When making the said optical filter, a sacrificial layer is deposited on one plate with the mirror coating. A mirror coating is then deposited on top and the second transparent plate is attached through a layer of hardening material. After that the said plates are attached to holders through a hardening material and the sacrificial layer is removed through evaporation by heating to temperature below the thermal destruction temperature of the hardening layer.
EFFECT: easier obtaining of controlled spacing between plates, avoiding use of special methods of obtaining surfaces with high degree of flatness, avoiding the need to monitor the value of the spacing and its wedge.
SUBSTANCE: fibro-optical connector comprises first and second half-couplings to receive first and second sections of optical fiber. First and second pairs of step-down optical multilayer transformers are arranged on end faces of said sections. Air gap is arranged between outer layers of said first and second pairs of said transformers. Layers of first and second pairs of aforesaid transformers are made from materials with differing indices of reflection and are counted from outer layers of aforesaid transformers in direction of the end faces of connected sections of optical fiber. Thickness of every layer makes one fourth of average signal wave λ0 transmitted over optical fiber, while the number of layers is selected subject to conditions covered by invention claim.
EFFECT: reduced power loss, expanded performances.
4 cl, 9 dwg