Interference mirror


(57) Abstract:

Usage: to create was highly reflective mirrors with guaranteed low value of the transmittance, mainly for IR laser technology. The essence of the invention: interference in the mirror that includes an optically polished substrate and a deposited metal reflective coating, was highly reflective layer of metal has a thickness of from 0.03 to 0.06 μm, and the substrate and adhesively pestiviruses layers made of optically transparent material. This was highly reflective layer of metal may be made of silver or gold, or copper, or aluminum. 1 C.p. f-crystals, 1 Il.

The invention relates to an optical instrument, in particular to the technology of optical coatings, and can be used for manufacturing was highly reflective mirrors with guaranteed low value of transmittance for measuring systems, mainly in the infrared laser technology.

Interference coatings have found wide application in optical instrumentation, including laser technology, in particular in technological lasers. In the system of measuring the radiation power of technological lasers frequent the rate of transmission. In this case the output power of laser radiation are judged by a small part of the output via the "back" of the resonator mirror and measured by the light receiver.

Typical requirements for such cavity mirrors are high reflectivity, at least 99% due to the minimal loss in the resonator, and the guaranteed value of the transmittance of 0.5% due to the necessity of the withdrawal of a certain small part of the radiation from the resonator. In the latter case, the mirror acts as a reliever powerful radiation to the radiation detector. A necessary requirement for such mirrors are minimal loss to scattering and absorption.

Traditionally, such mirrors are optically polished substrate is transparent at the operating wavelength of the material, which is applied to multilayer interference mirror coating of the form P(HB)pwhere P - substrate, N and alternating, usually a quarter-wave interference layers having low and high refractive indices, respectively, p is the number of pairs of interference layers. So, for example, infrared rear resonator mirror on a substrate of germolene of 1.35 and 2.4, respectively, which is typical for optical companies in the USA. In another case, the interference mirror coating consists of 10 to 12 layers of zinc selenide and germanium having a refractive index of 4.0.

The main disadvantages of such conventional solutions of mirrors, especially for the infrared radiation, are relatively high complexity due to the large number of layers and increased losses on the scattering and absorption, which in the last analogue can reach 1%

Known technical solution (prototype) was highly reflective mirrors, mainly for the infrared radiation, in which an optically polished substrate deposited reflective coating type P AND1Me A2(HB)pwhere the substrate is made of metal, AND1and a2adhesively pestiviruses layers of chromium and ZnSe, respectively, Me - reflective layer of silver of a thickness of 0.1 to 0.15 μm, N and quarter-wave interference layers of ThF4and ZnSe, respectively, in the amount of from two to three pairs. These mirrors achieve a high reflectance factor up to 99.5 99.8%, including at a wavelength of 10.6 μm, which is necessary for technological CO2-lasers.

The main disadvantage of the prototype in relation to "rear which I receive a guaranteed small values of transmittance at high value of the reflection coefficient, not less than 99,0%

This goal is achieved by the fact that in the known structure of metal-dielectric mirror substrate and adhesively pestiviruses layers made of optically transparent at the operating wavelength of the material, and the layer was highly reflective metal such as silver, gold, copper, aluminum, and has a thickness of from 0.03 to 0.06 μm.

The proposed solution has the following essential features of novelty. The first sign of a substrate and adhesively pestiviruses layers made of optically transparent material. This is due to the need to obtain a guaranteed transmittance. The choice of substrate material in accordance with this requirement is, for example, by reference. Adhesively pestiviruses layers with a thickness of 0.05 to 0.2 μm apart from the main purpose of improving the adhesion of the metal layer with the substrate and amplifying the interference layers act as diffusion barrier for stabilizing the structure of the metal layer and the preservation of its optical and physical characteristics. To assess the correctness of the choice of material adhesively passivating layers is convenient to use a valid value of absorption at the operating wavelength is not more than the IRS silicon (SiO2), we obtain RF-cathode technology in a single technological process was highly reflective layer of metal.

The second sign was highly reflective layer of metal has a thickness of from 0.03 to 0.06 μm. In relation to this type of mirror it is reasonable to believe was highly reflective of those metals which, when the layer thickness of not less than 0.1 μm are at the working wavelength reflectance not less than 99% for example, silver in the area longer to 0.75 μm gold longer than 1.5 μm, the copper is longer than 10 μm and aluminum long to 20.0 μm. It is widely known application of these materials as a broadband mirror coatings, in this case, the layer thickness is not less than 0.1 μm, and the transmittance is equal to zero. It is also known to use layers was highly reflective of the metals in the composition of the metal-dielectric filters, where the thickness of the layer is chosen from a transmittance of a few percent. It is also known to use layers of aluminum as the output mirror coatings for excimer laser at a wavelength of 172,5 nm. The thickness of the aluminum layer was 0,021 mm, which ensured that the reflection coefficient of 73% and a transmittance of 3.0% As you can see, the last example does not implement the in, for example of copper obtained cathode magnetron technology, when the transmittance (0,1 -0,2)% had a sufficiently high reflection coefficient (98,0 98,8)% at a wavelength of 10.6 μm, which corresponded to a layer thickness of from 0.04 to 0.03 μm, respectively. In the patent and scientific literature, the use of partially transparent layers was highly reflective metals in the composition was highly reflective mirrors with a guaranteed low value of the transmittance was not found.

In the drawing conditionally in cross section showing the proposed design was highly reflective mirrors, where: 1 substrate of optically transparent material, 3 partially transparent layer was highly reflective metal, which on both sides framed adhesively pestiviruses layers 2 and 4, over the last applied amplifying the reflection of the interference layers 5. The radiation is directed to the mirror side of the interference layers, not less than 99,0% of the energy is reflected and not less than 0.05% passes through the mirror and is supplied to the radiation receiver.

The proposed mirror is implemented as follows.

On the basis of the operating wavelength, choose a substrate material, such as germanium for a wavelength of 10.6 microns, or optical is 11141-84 and in accordance with the requirement of drawing the shape of the surface. Then the method of cathode sputtering in a single technological cycle is applied consistently adhesively passivating layer is then partially transparent layer was highly reflective metal such as silver, and then adhesively passivating layer, for example silicon dioxide with a thickness of 0.05 to 0.2 μm. The thickness of the partially transparent layer was highly reflective metal is selected in the range from 0.03 to 0.06 μm on the magnitude of the reflection coefficient, which must be not less than 98% and a transmittance of not less than 0.1% together with the substrate and pestiviruses layers. Thus the criterion for the correctness of the choice of material and thickness of the adhesion-passivating layers is valid absorption of not more than 0.1% Next any vacuum applied technology enhances the reflection of the interference layers General view (HB)pwhere N and - interference, basically a quarter-wave at the operating wavelength layers with low and high values of refractive index, n the number of pairs of such layers (at least one). It should be noted that the total optical thickness of the adhesion-pestiviruses layer AND2and the nearest layer with low refractive index must be equal to a quarter of the working wavelength. 2 and with the high value of the refractive index of refractory oxides of zirconium, hafnium, titanium and other operating wavelength of 10.6 microns as amplifying the interference layers are materials ThF4and ZnSe (based on the experience of firms in the U.S.) or ZnSe and Ge, or in our experience materials ZnSe and telluride Germany (GeTe) with a refractive index n of 3.7. The principle of selecting the number of pairs of interference layers such that, when the minimum number to obtain a reflectivity of more than 99% [7] In particular, for materials ZnSe and GeTe enough one pair of quarter-wave interference layers to get10,699,0 and10,60,05%.

The proposed solution is illustrated by the following example. We have made was highly reflective resonator "rear" mirror with a guaranteed low value of transmittance for technological CO2laser type t is 1.5. produced in SIC t RAS. Conventionally, the design of such mirrors can be written as: P SiO2CuSiO2ZnSeGeTe, where P is the substrate of Germany, Cu partially transparent layer of copper with a thickness of 0.03 to 0.04 μm, the applied cathodic magnetron technology, and the exact thickness of this layer was determined by optical characteristics10,698% and10,6of 99.3-99.5% and10,6= 0,05-0,1%. Such mirrors are successfully used in the composition of the resonators of technological lasers type TL-1.5, if the power density of up to 1.0 kW/cm2when the output of the laser power up to 1.5 kW, ensuring the functioning of the integrated system for measuring average power is the same.

Thus, in comparison with analogues reduced the complexity of manufacturing mirrors by reducing the number of layers and significantly reduced losses by scattering (more than an order of magnitude). Compared with the prototype at a high value of the reflection coefficient obtained guaranteed transmittance satisfying the requirements of an embedded system average power measurement radiation technology CO2laser type t is 1.5.

1. Interference mirror comprising an optically polished substrate and a deposited mirror coating


where n substrate;

IU was highly reflective layer of metal;

A1 and A2 adhesively pestiviruses layers with a thickness of 0.05 to 0.2 microns;

N and amplifying the reflection of alternating layers of low and high rates which has a thickness of from 0.03 to 0.06 μm, and the substrate and adhesively pestiviruses layers made of optically transparent material.

2. Mirror under item 1, characterized in that the layer was highly reflective metal made of silver, or gold, or copper, or aluminum.


Same patents:

Ar coating // 2097801
The invention relates to an optical instrument, in particular for the optical coatings and can be used to create a walk-through optical element (OE) of the semiconductor materials (PMM) with antireflection coatings for infrared (IR) radiation, which can be used in the process of laser systems

The invention relates to an optical instrument, in particular an interference coatings, and can be used to create the output mirror of the resonator powerful technological CO2lasers

Interference mirror // 2091826

Bandpass filter // 2079861

The invention relates to optoelectronics and integrated optics and can be used to create a structurally stable narrow-band interference filters, logical optical elements and picosecond optical keys UV, visible and IR frequency range

Ar coating // 2057351
The invention relates to the technology of optical coatings and can be used in an optical instrument for enlightenment parts

The invention relates to the treatment of hard surfaces, in particular for the application of coatings on optical parts, and can be used in laser technology

The invention relates to laser technology, namely the polarization of the laser mirrors

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.

22 cl

Reflecting surface // 2256942

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.

5 dwg

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.

5 dwg

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.

5 dwg

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

FIELD: physics.

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.

1 dwg

FIELD: physics.

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