RU2021590C1 - Method of measurement of parameters of outside action on medium or object and device to implement it - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: flux of electromagnetic radiation excites surface electromagnetic wave in metal film. Reference medium is placed in this case in zone of propagation of electromagnetic radiation and/or surface electromagnetic wave. Electric signal between metal film and semiconductor substrate carries information on outside actions which change parameters of reference medium. EFFECT: improved authenticity of measurement of parameters. 22 cl, 7 dwg

Description

 The invention relates to non-contact methods for studying the characteristics of external influences on the environment, mainly of biological origin, and / or in contact with biological objects of the environment, the parameters of which determine the vital activity of these biological objects.

 A known method of measuring the parameters of external effects on the environment or object, including registration by means of an appropriate sensor, for example, a sensor of a magnetic or electromagnetic field, converting the signal from the sensor and its visualization.

 In this way, the parameters of external influences are recorded in most cases, however, the sensor introduces significant errors in the registration process, which are eliminated only by sophisticated technical means of correcting the received signal.

 Also known is a method of measuring the parameters of external action, including transmitting a stream of electromagnetic radiation through the medium, for example, a fiber having particles whose properties depend on the selected external effect, for example, single-domain particles with magnetization vectors parallel to the longitudinal axis of the fiber. Then, the phase shifts of the transmitted optical wave are used to judge the magnitude of the recorded parameter, in particular the magnetic field.

 The disadvantage of this method is that for the registration of information it is necessary to use an interferometer or other rather sophisticated optical equipment, which in some cases, for example, in field or industrial research, makes it difficult or completely excludes the possibility of the necessary registration.

 Closest to the claimed one is a method of measuring the parameters of an external influence on a medium or an object, including setting control dependences of the response signal on the external influence on a reference sensitive medium, exposure to one of the sides of a structure made of a metal film deposited on a substrate by an electromagnetic radiation flux, s the location of the aforementioned medium from the side of the metal film of the said structure, the excitation in the metal film of a surface electromagnetic wave and the formation the response signal from this structure, compared with which control parameters are judged on the measured parameters.

 This method is implemented by means of a device containing a source of electromagnetic radiation, a solid-state structure consisting of a metal film deposited on a substrate for excitation in the last surface electromagnetic wave, a volume with a reference sensitive medium located on the side of the metal film, and an information processing unit.

 The mentioned method allows recording the parameters of external influences by means of the specified device using a non-contact method with high accuracy, however, in this case, it is necessary to use a special channel for recording the electromagnetic radiation flux reflected from the metal film, including the corresponding optical circuit and a photoconverter, which significantly complicates the method and device. The use of a fixed or flexible arrangement of the elements of the aforementioned optical circuit leads, respectively, to severely limit the measurement range and scope, or to its sharper complication and cost of the method and device and reduce the accuracy of measurements.

 The aim of the invention is to improve the technical and operational parameters of both the method and the device, and simplification in use.

 This goal is achieved in part of the method in that a semiconductor layer is used as a substrate on which a metal film is applied (directly or through an intermediate layer with a higher resistivity than metal), an electrical signal is recorded directly in the circuit between the metal film and a semiconductor layer, while this electrical signal is used as a response signal from the above structure.

 In this case, an electric signal is recorded on the slope of the resonance curve of the magnitude of the aforementioned signal from at least one of the coordinates of the flow direction and / or frequency of electromagnetic radiation, using a diverging or converging, or collimated flow of electromagnetic radiation, which can be either monochromatic or and non-monochromatic, as well as linearly polarized, and the flow of this stream can be carried out either directly or through an optical fiber. To expand the measurement range, one of the angular coordinates of the direction of the flow of electromagnetic radiation relative to the specified structure or the frequency of electromagnetic radiation is changed.

 This goal in terms of the device is achieved by the fact that the substrate is made of semiconductor material, and the inputs of the information processing unit are connected directly to the metal film and the substrate. The film and the substrate are directly adjacent to each other or through an intermediate layer, the resistivity of which exceeds the resistivity of the said metal film, and the interface in both cases can be partially or fully spatially modulated.

 The source of electromagnetic radiation can be configured to readjust the frequency of radiation and / or to change the direction of propagation of the electromagnetic wave from this source relative to the position of said solid state structure.

 To ensure the SEW excitation, the surface of the metal film from the side opposite to the location of the semiconductor layer is spatially modulated, or the device is equipped with a means (for example, a prism) to ensure complete internal reflection from its output face. This face can be set with a gap relative to the surface of the metal film in such a way that a layer of a substance is located in the said gap, the refractive index of which is less than the refractive index of the medium of said medium.

 In addition, the device may be equipped with means for polarizing the flow of electromagnetic radiation and an optical fiber for supplying a flow of electromagnetic radiation.

 Compared with the known technical solutions, the claimed one allows measurement of the parameters of the external influence on the medium or object without using the channel for recording the reflected optical signal, but directly by recording the electric signal corresponding to the values of the studied parameters of the effect. This allows not only to expand the scope of application of the method and device, since in this case the dimensions of the device are significantly reduced, but also significantly simplify the work, increase the accuracy and range of measurements, dramatically reduce the cost of the method and device. The device as a whole (apart from the registration unit) takes the form of an optoelectronic pair — a hybrid circuit, parts of which, emitted and received, are realized on the basis of mass industrial microelectronic production.

 As shown by a search carried out on scientific, technical and patent literature, the claimed combination is unknown, that is, it meets the criterion of "novelty."

 In FIG. 1 shows a reference sensitive medium located in the field of propagation of radiation and SEW; in FIG. 2 - the same, in the field of radiation propagation and outside the area of SEW; in FIG. 3 and 4 are variants of a device with lattice excitation of SEW (in Fig. 3, the reference sensitive medium is in the region of propagation of SEW, in Fig. 4 is outside it); in FIG. 5 and 6, the SEW excitation is realized by the method of impaired total internal reflection from the output face of the prism (in Fig. 5 such a prism is formed by the reference sensitive medium itself, and therefore this medium is located in the SEW region; in Fig. 6, the reference sensitive medium is located on the radiation path outside the area of SEW); in FIG. 7 is an example of a control dependence.

 The claimed method is based on the fact that the sensitive medium 1 is subjected to the studied effect, the response of which to this effect is to change the parameters of the electromagnetic waves propagating in its volume (radiation and / or SEW). The measure of such a change is known (in a standard way it corresponds to the value of the parameters of the studied effect. Examples of media and effects of this kind can be: a material that changes its optical density or tensor of dielectric constant depending on mechanical stress or thermal effect; a layer of electro-optical material that changes its dielectric constant tensor under the influence of an electric field; a layer of magneto-optical material rotating the direction of polarization of the incident radiation cheniya by the magnetic field, and so on. d. Thus, the problem of measuring external influence parameters is reduced to the reference test sensitive medium 1.

A solid state structure 2 is used to test medium 1. Its most important elements are a metal film 3 (for example, Ag, Au, Al, Cu) and a semiconductor substrate 4 (for example, Si, GaAs, InP). The medium 1 is positioned relative to the structure 2 from the side of the film 3 so as to ensure its interaction with the SEW on the surface of the film 3 and / or with the exciting SEW electromagnetic radiation. The film 3 and the substrate 4 can either directly border on each other, or be separated by a thin layer of intermediate material 5 (for example, SiO ₂ ). The latter with a resistivity exceeding the resistivity of the film 3 is sometimes specially introduced to set the desired ohmic transition resistance of metal 3 — semiconductor 4. The interface between metal 3 and semiconductor 4 or at least one of the layer surfaces can be spatially modulated (for example, periodically profiled) for amplification of the scattering of SEW from metal 3 into semiconductor 4. To the film 3 and the substrate 4 through the ohmic contact 6 are connected electrical leads 7 and 8, respectively, by which trukturu 2 connected to the measuring circuit as a photocell or a photodiode. The recorded value is an electric (volt) signal.

 The source of electromagnetic radiation 9 (usually visible or infrared) on the surface of the film 3 facing the medium 1, surface electromagnetic waves (SEW) are excited. The excitation of SEW is accompanied by resonant amplification of the electrical signal. By registering this signal and comparing its distinctive features (for example, the magnitude, position of the maximum depending on the angle of incidence or radiation frequency) with the control dependences on the studied parameter of the external influence (determining some parameter of the reference medium 1), determine the value of the latter.

 To implement this method, a device is proposed, some of the possible schemes of which are given in FIG. 3-6.

 The device consists of a measuring head 10 and a block 11 for processing and displaying information connected by wires 7 and 8.

 The measuring head is made on the principle of an optoelectronic pair — a source and a receiver of radiation.

 As the source 9 of electromagnetic radiation, it is preferable to use a built-in semiconductor emitter or output end of the optical fiber, which ensures the compactness of the measuring head. The radiation source 9 may be adjustable in frequency and / or in the direction of radiation relative to structure 2. In FIG. 3-6 schematically shows the possibility of angular displacement and reading of the angle by means of an angular scale 12 with a nonius 13. By scanning in frequency and moving in the angular coordinate of the radiation source, the device can be adjusted and adjusted, and control dependencies can be removed. Instead of an angular scale and nonius, it is advisable to use a potentiometric sensor for the angular position of the radiation source 9. It allows you to convert the angle value into a volt signal and, for example, on a two-coordinate recorder or in the computer’s memory, immediately obtain the dependence of the information signal on the angle for any method of scanning by angle. To achieve high accuracy of scanning by angle, an electromechanical scanner controlled from block 11 can be used. At the output of radiation from source 9, a polarizer and a micro lens can be provided. Accordingly, it is advisable to use a potentiometric sensor of the angle of rotation of the polarizer to remove the dependence of the signal on the direction of polarization.

 The solid state structure 2 described above is used as a radiation receiver.

 To excite the SEW by the lattice method on the surface of a metal film 3 not facing the semiconductor 4, this surface is spatially modulated, for example, in the form of a sinusoidal lattice (Figs. 3 and 4). To excite the SEW by the method of impaired total internal reflection in the schemes of FIG. 5 and 6, a prism 14 is used, which is rigidly fixed relative to structure 2 according to the standard Otto SEW excitation method, forming a gap 15 filled with air or another dielectric with a lower refractive index than that of prism 14. In the circuit of FIG. 5, the role of the prism 14 is played by the wedge-shaped layer of the reference medium 1 located on the path of the radiation beam, the refractive index of which is obviously larger than that of the substance in the gap 15.

 The device operates as follows.

 In the diagrams of FIG. 4 and 6, a change in the reference medium 1 subjected to the studied external influence leads to a change in the direction of incidence of radiation on structure 2 or to a change in the direction of polarization of this radiation. In the diagrams of FIG. 3 and 5, the studied effect can change, in addition, also the magnitude of the SEW wave vector. Each of these factors changes the characteristics of the signal recorded from the measuring head 10, respectively, to external influence.

 The basis of the proposed method and the principle of operation of the device are the following physical phenomena.

=

- волновой вектор падающего излучения частотой ω и длиной волны λв вакууме;
n - показатель преломления диэлектрической среды 1;
n_призмы - показатель преломления призмы 14;
θ - угол падения излучения на решетку или на выходную грань призмы;
m - целое число m≠0).As is known, SEWs at the interface between media, in particular metal 3 and dielectric medium 1, are excited by converting the incident p-polarized electromagnetic radiation from source 9 through prism 14 under conditions of impaired total internal reflection from its output face Rn of the _prism sinθ = R _pev ( 1), or lattices on the metal surface 3 Rnsin θ + mG = R _pev , (2) where R =

=

- wave vector of incident radiation with frequency ω and wavelength λ in vacuum;
n is the refractive index of the dielectric medium 1;
n _prisms is the refractive index of the prism 14;
θ is the angle of incidence of radiation on the grating or on the output face of the prism;
m is an integer m ≠ 0).

- обратный вектор решетки периода Λ; а
R_пэв= ±

$\genfrac{}{}{0ex}{}{\text{("+}}{\text{"-"}}$ ^" _д $\genfrac{}{}{0ex}{}{\text{дл}}{\text{ля}}$ ^я _m $\genfrac{}{}{0ex}{}{\text{m>0}}{\text{<0)}}$ ^,
(3) представляет собой волновой вектор ПЭВ. Здесь, в свою очередь, ε_Me' - действительная часть диэлектрической проницаемости металла 3 на частоте ω (обычно ε_Me'<0 |ε_Me'|>>1 ).G =

is the inverse lattice vector of the period Λ; and
R _pev = ±

$\genfrac{}{}{0ex}{}{\text{("+}}{\text{"-"}}$ ^" _d $\genfrac{}{}{0ex}{}{\text{dl}}{\text{a la}}$ ⁱ _m $\genfrac{}{}{0ex}{}{\text{m> 0}}{\text{<0)}}$ ^,
(3) is a wave vector of SEW. Here, in turn, ε _Me 'is the real part of the dielectric constant of metal 3 at a frequency ω (usually ε _Me '<0 | ε _Me '| >> 1).

 Equalities (1) and (2) describe the position of the resonance maximum of the conversion efficiency (the fraction of the radiation energy converted to SEW energy) depending on R, n, and θ. If one of these parameters changes (for example, n the resonance position changes (resonance values of R and θ); if this parameter changes within the width of the resonance curve, the conversion efficiency changes sharply. Hence the method for determining n adjacent to the metal film 3 of the medium 1, and on its basis, also a method of measuring the parameters of external influence on medium 1, which manifests itself in a change in n.

 Firstly, the refractive index n of medium 1 and, accordingly, the value of the external exposure parameter can be determined by measuring the values of θ and ω at which the resonance of the efficiency of radiation conversion to SEW at the medium – metal 32 interface is observed 32. Comparing these values with the calculated or experimental control by the dependences of the resonance values of θ and ω on the parameter of external influence on medium 1, one can find the value of the latter.

Secondly, it is possible to set θ and ω so that the value of the conversion efficiency corresponds to the slope of the resonance curve for medium 1 with a known value n = n _о and, accordingly, for some known (initial) value of external influence on it. Measurement of exposure parameters is carried out relative to such an initial value based on measuring the difference of the corresponding values of the conversion efficiency within the resonance curve and comparing the value of this difference with the control dependence.

 In practice, it is more convenient to measure not the conversion efficiency itself, but some kind of signal that depends on it.

 Such a signal is easily obtained if the metal film 3 is aligned with the substrate 4 of a semiconductor material. In this case, the value of the conversion efficiency of radiation into SEW determines the magnitude of the electric signal taken from the terminals 7 and 8, connected directly to the film 3 and the substrate 4. In this case, the film 3 and the substrate 4 form a structure 2 similar to a conventional Schottky photodetector. Structure 2, like a photodetector, can be connected via the indicated terminals 7 and 8 as a photodiode or photocell. It differs in that the signal from it has a resonant maximum under the conditions of excitation of SEWs at the interface between medium 1 and metal 3.

 The nature of the connection between the SEW and the electrical signal here may be different. A mechanism based on the absorption of SEWs in a metal film 3, the generation of hot charge carriers in it, and the emission of the latter into semiconductor 4 through a Schottky barrier is known. Such carriers are carried away by the Schottky barrier field and determine the electric response of structure 2. Moreover, the energy of the radiation quantum was less than the band gap of the semiconductor. It was noted that radiation for exciting SEWs can be supplied to a metal film both through air and through a semiconductor. In the case when the radiation quantum energy is greater than the band gap of the semiconductor 4, the formation of electron-hole pairs in the semiconductor 4 is possible either directly due to the penetration of the SEW into the semiconductor 4, or due to the reverse conversion of the SEW into radiation at the metal 3 - semiconductor 4 interface and absorption last semiconductor. Electron-hole pairs are separated by the Schottky barrier field and cause a photoresponse, as in a conventional photodetector. Obviously, radiation for excitation of SEW here can be supplied only from the side opposite to the semiconductor.

 Thus, the value of the parameter of the external influence on the medium 1, affecting its refractive index, can be determined by registering and comparing with the control value the position of the maximum of the photoelectric signal taken from the structure 2 metal 3 - semiconductor 4 under the conditions of excitation of electromagnetic radiation, when scanning along the angular coordinate radiation directions relative to structure 2 or in terms of radiation frequency. For measurements within the width of the resonance curve, a different mode of operation is preferable. If the direction and frequency of the radiation are chosen on the slope of the resonance curve of the corresponding dependence of the photoelectric signal, then structure 2 will work as a direct converter of the magnitude of the external influence parameter into the photoelectric signal. Accordingly, by registering the signal and using the previously taken control dependence of it on the parameter of the external influence, the magnitude of the latter can be measured. In this mode, the sensitivity to external influences is proportional to the slope of the resonance curve. The width of the dynamic range in magnitude of this effect, on the contrary, is proportional to the width of the resonance curve. The divergence of the radiation and the spectral width of the radiation source 9 contribute to the width of the resonance curve. Obviously, to achieve maximum sensitivity, monochromatic and collimated radiation should be used. To expand the dynamic range, one can use diverging (converging) or spectrally broadened radiation.

 Within the framework of the principle considered, optically anisotropic medium 1 can also be used. In this case, the measurement conditions should be chosen so that the external influence affects those components of the dielectric constant tensor of medium 1 that describe the propagation of SEW in medium 1 and radiation of the corresponding polarization.

To measure the parameters of the external influence on the reference sensitive medium 1 by the proposed method, it is not necessary that the medium 1 directly borders a film of metal 3. A layer 16 (see Fig. 1-4) can be applied to the surface of metal 3 for auxiliary purposes, for example, to improve adhesion, protection of the film 3 from possible chemical influences, etc. The wave vector of SEW in such a multilayer system is no longer described by simple expression (3). The dependence of R _pev on n medium 1 and, accordingly, on the external action for a not too large layer thickness 16 continues to take place, although it becomes weaker as it increases.

 The medium 1 does not have to be displaced with the structure 2. The properties of the medium 1, remote from the structure 2 by a distance exceeding the penetration depth of the SEW and exposed to external influences, can affect the excitation of the SEW through the direction of the radiation passing through it. Obviously, the layer of medium 1 in the path of the radiation beam should have the shape of a wedge if the refractive index in space before and after this layer is the same.

 In all cases, all of the above regarding the measurement method and the principle of operation of the device continues to be valid.

The proposed measurement principle may be based on the dependence of the photoelectric signal, which is a response to the SEW excitation, not only on the refractive index, but also on the polarization characteristics of medium 1, which change in a standard way under the influence of external influence. So, if the magnitude of the rotation of the plane of polarization of the radiation when it passes through medium 1 depends on the measured parameter of the external influence (for example, the Faraday rotation of the plane of polarization in a magnetic field), then the component of the radiation polarization vector, which contributes to the excitation of the SEW, and, therefore, The signal also depends on the measured parameter. This dependence, unlike those based on a change in the refractive properties of medium 1, is not resonant, but has the form cos ² (Φ - Φ _o ), where Φ is the angle of rotation of the polarization direction. To register this dependence, it is necessary to use linearly polarized radiation.

A specific example of the application of the proposed method. The magnitude of the induction component of the magnetic field of the coil was measured according to the circuit of FIG. 2. As a reference test medium 1, we used a semi-magnetic semiconductor Cd _0.55 Mn _0.45 Te, characterized by a giant Faraday rotation. A plane-parallel Cd _0.55 Mn _0.45 Te plate in the form of a disk 5.8 mm thick was placed inside the coil perpendicular to its axis. Radiation of He-Ne laser LGN-203 (wavelength of 0.6328 micron, TEM _oo mode, the divergence ^of 0.65, power of 1.65 mW) directed along the axis of the coil and passed through the plate. The direction of polarization of the radiation incident on the plate was set by the polarizer. The radiation was received by a periodically profiled structure 2 formed by depositing a thin film of 3 Ag on a 4 n-GaAs substrate 4 with a sinusoidal corrugation period of 0.46 μm. The structure 2 was placed in a frame that allows you to adjust the angular position of the structure 2 relative to the direction of incidence of radiation, and the plane of incidence of radiation was perpendicular to the direction of the corrugation. A negative bias of 1.4 V ("+" on n = GaAs, "-" on Ag) from the VIP-010 power supply was applied to structure 2. A signal from a load of 40 kΩ was recorded on the screen of a S9-8 digital oscilloscope with an input impedance of 1 MΩ. The coil was powered by a DC source B5-49. When removing the control dependence, a standard teslameter based on a Hall sensor was used to measure magnetic induction in the direction perpendicular to the plane of its probe.

For measurements, the angle of incidence of radiation on the solid state structure 2 was set near the resonance maximum of the photoelectric signal. The polarization direction was fixed and amounted to an angle of about 45 ^° with the plane of incidence of radiation. The control dependence of the response signal on the magnetic field of the coil is shown in FIG. 7. Dependence is a section of a sinusoid. The asymmetry of its position with respect to zero along the B axis (the sine wave is shifted approximately 10 mT to the left) corresponds to a detuning of the direction of radiation polarization from 45 ^° . Obviously, by specifying the magnitude of this detuning, one can shift the linear portion of the control dependence into the range of values of B.

 When the measuring device was placed in the region of the tested magnetic field, a signal V = 40 ± 0.1 mV was recorded. According to the control dependence of FIG. 7, the longitudinal component of the magnetic field was determined B = 5.8 ± 0.02 mT.

 Thus, the use of the proposed method allows to measure the parameters of the external influence with high accuracy without obvious restrictions on the width of the dynamic range. The proposed method differs from others based on the SEW resonance in that it does not imply complex optical schemes with the need to align two radiation beams. Moreover, this method allows you to implement a direct conversion of the measured value into an electrical signal. It provides the ability to quickly take measurements not only in the laboratory, but also in domestic, industrial and field conditions. Measurements can be carried out by inexpensive means, the production of which is implemented on the basis of industrial microelectronics technology.

Claims (22)

 1. A method of measuring the parameters of external influence on a medium or an object, including setting control dependences of the response signal from external influence on a reference sensitive medium, the action on one of the sides of a structure made of a metal film deposited on a substrate, by a stream of electromagnetic radiation, with the location of the medium from the side of the metal film of the aforementioned structure, the excitation in the metal film of a surface electromagnetic wave and the formation of a response signal from this jet tours, compared which the control dependencies are judged on the measured parameters, characterized in that as a substrate using semiconductor layer, recorded electrical signal in the circuit between the metal film and the semiconductor layer, wherein the electrical signal is used as a response signal from said structure.  2. The method according to claim 1, characterized in that between the metal film and the semiconductor layer have an intermediate layer, the resistivity of which exceeds the resistivity of said metal film.  3. The method according to claim 1, characterized in that one of the angular coordinates of the direction of the flow of electromagnetic radiation is changed relative to the specified structure.  4. The method according to claim 1, characterized in that the frequency of the electromagnetic radiation is changed.  5. The method according to claim 1, characterized in that the electrical signal is recorded on the slope of the resonance curve of the magnitude of the signal from at least one of the coordinates of the direction and / or frequency of electromagnetic radiation.  6. The method according to p. 1, characterized in that they use a diverging or converging stream of electromagnetic radiation.  7. The method according to p. 1, characterized in that they use a collimated flow of electromagnetic radiation.  8. The method according to claim 1, characterized in that the flow of monochromatic electromagnetic radiation is used.  9. The method according to claim 1, characterized in that use the flow of non-monochromatic electromagnetic radiation.  10. The method according to claim 1, characterized in that they use a stream of linearly polarized electromagnetic radiation.  11. The method according to claim 1, characterized in that the flow of electromagnetic radiation to the medium is carried out through an optical fiber.  12. A device for measuring the parameters of external influence on a medium or an object containing a source of electromagnetic radiation, a solid-state structure consisting of a metal film deposited on a substrate for excitation in the last surface electromagnetic wave, a volume with a reference sensitive medium located on the side of the metal film of the said structure, and an information processing unit, characterized in that the substrate is made of semiconductor material, and the inputs of the information processing unit are connected to metal film and substrate.  13. The device according to p. 12, characterized in that the interface between the metal film and the semiconductor material is partially or fully spatially modulated.  14. The device according to p. 12, characterized in that between the metal film and the semiconductor material is an intermediate layer, the resistivity of which exceeds the resistivity of said metal film.  15. The device according to PP.12 and 14, characterized in that at least one of the surfaces of the said intermediate layer is partially or fully spatially modulated.  16. The device according to p. 12, characterized in that the source of electromagnetic radiation is configured to be tuned by the frequency of radiation.  17. The device according to p. 12, characterized in that it is made with the possibility of changing the position of the said solid-state structure relative to the direction of propagation of the electromagnetic wave from the source of electromagnetic radiation.  18. The device according to p. 12, characterized in that the surface of the metal film from the side opposite to the location of the semiconductor layer is spatially modulated.  19. The device according to p. 12, characterized in that it is equipped with a means to ensure complete internal reflection from its output face.  20. The device according to paragraphs. 12 and 19, characterized in that the output face of the said means forms a gap with the surface of the metal film in which the layer of the substance is located, whose refractive index is less than the refractive index of the medium of the said means.  21. The device according to p. 12, characterized in that it is equipped with a means for polarizing the flow of electromagnetic radiation.  22. The device according to p. 12, characterized in that it is equipped with an optical fiber for supplying a stream of electromagnetic radiation.

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