Bandpass filter


(57) Abstract:

Usage: in optical devices, for example, in astronomy. The inventive substrate, made in the form of a film filter, low pass wavelength region, the transmittance caused multilayer interference coating. 2 Il.

The invention relates to an interference optical systems and can be used in various optical devices, filtering the radiation spectrum, for example, in astronomy, spectral and space research.

Known interference filter [1] containing substrate with a multilayer coating consisting of two systems of alternating layers of dielectrics with high and low refractive index, and has a matching layer material with a low refractive index, located between layers.

The closest technical solution to the present invention is an optical filter [2] containing a substrate made of colored glass that has the characteristics of a bandpass filter, and a multilayer interference coating on the substrate comprising alternating layers of dielectrics with high and low indices of refraction is s as substrate glass bandpass filter limits the use of optical filters, because for example, in the manufacture of large optics significantly increases the weight of the device. In addition, the manufacture of glass bandpass filters time-consuming and costly process.

Object of the present invention is to provide a bandpass filter of simplified construction and reduced weight.

The problem is solved due to the fact that in the bandpass optical filter containing a substrate and a multilayer interference coating of alternating layers with high and low refractive indices, according to the invention as the substrate material used film optical filter having the characteristics of the filter, low pass wavelength region bandwidth.

On film filter deposited multilayer interference reflector with a band of high reflectivity, which is obtained using multilayer coatings consisting of alternating transparent dielectric layers with high and low refractive indices.

Declare bandpass filter differs from the prototype in that the substrate is in the form of a film filter polymer base.

Performing a substrate film SiteFinity bandpass filter, lightweight and simplified design with predetermined optical characteristics to help in the spectral range to select the desired bandwidth.

In Fig. 1 shows the design of the bandpass filter of Fig. 2 shows the spectral characteristic of the substrate of the thin film optical filter having wavelength border transmission (curve 1) and the substrate with a multilayer interference coating (curve 2), where the wavelength (nm); lothe wavelength of maximum reflection; half bandwidth, t is the transmittance (%).

The bandpass filter includes a substrate 1, and 2 layers with high refractive index (b) and 3 layers with low refractive index (N). Layers 2 and 3 form a multilayer interference coating.

The proposed bandpass filter is made by coating on a polymer base multilayer interference reflector with band high-reflection (80 to 95%) in a given region of the long wavelength absorption. Interference reflectors produced using the multilayer coatings consisting of alternating transparent dielectric layers with high, for example, ZnS or TiO2and low YF3or SiO2pokazateli between the refractive indices of the layers.

This coating can be expressed, for example, the following next:


where B and H of alternating layers of optical thickness of l/4 with high and low refractive indices n, respectively,

S1 the surface of the substrate,

S2 environment.

Bandpass optical filter works in the following way. The short-wave boundary of the spectral transmission range provide a polymer substrate, coloured throughout the mass. Spectral absorption wavelength range provide dyes introduced into a polymer base, and the multilayer interference reflector form of long-wave boundary of the bandwidth.

Bandpass filter containing a substrate and a multilayer interference coating of alternating layers with high and low refractive index, characterized in that the substrate material used film optical filter having the characteristics of the filter, low pass wavelength region transmission.


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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