RU2568038C1 - Method to detect microconcentrations of flammable and toxic gases - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: method includes penetration of infrared radiation via controlled volume on working and reference wave lengths. Wave lengths are chosen so that radiation on the working wave length is absorbed, and on the reference wave length is not absorbed by gas. As sources of radiation they use two semiconductor radiators, which operate in pulse mode. Radiation from sources is focused in the plane of the radiation receiver. Radiators are equipped with interferential filters to narrow the radiation spectrum band. Durations of pulses of working and reference radiation are equal to each other. The radiator on the working wave length is started by clock pulses from the generator directly, and the reference radiator is started with a time delay. Signals received from the receiver of radiation arrive to two amplifiers. At the same time the amplifier for the reference wave length opens with a delay. Outlet signals of amplifiers are compared by a comparison system.

EFFECT: increased sensitivity.

2 cl, 6 dwg, 2 tbl

Description

The invention relates to measuring technique, and in particular to a method for detecting micro-concentrations of combustible gases long before the formation of an explosive mixture with air, toxic and other gases long before the formation of life-threatening concentrations, and can be used in solving problems of monitoring zones with possible leakages of these gases.

Currently, in the Internet search engines (Google, Yandex), you can find a large number of proposals for gas analyzers for a wide range of combustible and toxic gases. So, in [1, 2, 3, 4, 5, 6] the parameters of gas analyzers are given, the operation of which is based on the selective absorption of infrared (IR) radiation with a wavelength of 2–5 μm by gases of the hydrocarbon group. Detection of toxic and other gases hazardous to humans, based on the selective absorption of infrared radiation by these gases, is also possible by the proposed method.

Further analysis of the possible implementation of the proposed method will be carried out on the example of the detection of combustible gases of a hydrocarbon group in the wavelength range of infrared radiation 2 ÷ 5 μm.

In [7], which also uses absorbed absorption of wavelengths in the indicated range, it is proposed to increase the accuracy of measuring gas concentrations and increase the reliability by eliminating mechanical moving parts in the device.

The infrared gas analyzer described in [7] can be adopted as a prototype (analog) of the proposed method for technical performance and the achieved result.

The disadvantage of the prototype, as well as many analyzers from [1, 2, 3, 4, 5, 6] is the low sensitivity when detecting combustible gases (does not exceed 2 · 10 ^-3 atm, which is 10 times less than the explosive level). This disadvantage is caused mainly by the small size of the monitored volume (the small distance of the IR emitter - IR receiver).

Another disadvantage of the prototype is the complexity of the optical systems for transmitting the working and reference IR rays, as well as the presence of two IR receivers when registering these rays, the noise characteristics of which can be close, but never coincide. The latter drawback is important when registering micro-concentrations of toxic gases.

The disadvantage of gas analyzers with an infrared emitter in the form of a He-Ne laser is the high weight and high cost of these devices.

The technical result of the proposed method is to eliminate the above disadvantages of the prototype.

The detection of flammable gas leaks long before the formation of an explosive mixture with air of at least 0.0002 atm includes the operation of transmitting two infrared (IR) radiation close in value to the working λ _slave and reference λ wavelength _supports through a controlled volume in which the radiation at λ _{the slave} absorbs combustible gases, but does not absorb on the _pylons , while the output signals of the IR receiver, which is affected by the radiation on the _slaves and _pylons , form an information signal on the presence of leakage and its scale by the processing system. In accordance with the proposal of IR radiation for the lengths λ, the _slave and λ _{supports are} carried out by two semiconductor emitters, which operate in a pulsed mode and which are located next to each other so that the axis of the emitters is directed to the center of the IR receiver, and the distance of the IR emitters - the IR receiver forms a controlled space, while both IR emitters are equipped with interference filters that “narrow” the radiation spectrum, and the radiation itself is focused in the plane of reception of these emissions so that the size of the focused radiation establish from the condition D _rad ≤5 D _CR , the duration of the radiation pulses at λ _slave and λ _supports are equal to each other, Δt _slave = Δt _supports , and the clock frequency F _t , which sets the pulse mode of operation, set the clock generator from the equality

in this case, the IR emitter at λ _{slave is} triggered by clock pulses from the generator directly, and the emitter at λ _{poles is} triggered by clock pulses that delay for a time in the range

and provide temporary separation of IR radiation pulses by λ _slave and λ _supports , and the output pulse signals of the IR receiver are fed to the inputs of two amplifiers, which are closed at the input in the initial state and are opened synchronously with the appearance of the output pulses of the IR receiver, for which the amplifier by λ _slave open clock directly from the generator, and an amplifier λ _supports open clock that is delayed by a time T _back, wherein the operation amplifier is set to 0,9 Δt _slave, and the output signals of amplifiers Cf. ivayut in a comparison circuit, which output amplifier λ _slave is delayed by a time T _back; where D _rad and D _pr - respectively, the size of the focused radiation on λ _slave and λ _supports in the plane of the IR receiver and the size of the input window of the receiver, T _t - the repetition period of clock pulses, q - duty cycle of the pulse mode.

In another embodiment of the proposed method, the total operating time T _{sis is} limited in time in accordance with the expression

and the comparison circuit is equipped with a function of accumulating difference signals that occur on each period T _t , the number of which is set equal to N.

In the following, the explanation when substantiating the implementation of the proposed method is confirmed by the drawings.

FIG. 1 - spectral characteristics of the recommended IR emitters of the IL 151 A series at Δ _slave = 3.39 μm and λ _spec = 3.0 μm;

FIG. 2a is a simplified block diagram of IR emitters,

where 1 and 2 are emitters on λ _slave and λ _supports ,

3 and 4 - optical filters for λ _slave and λ _supports ,

5 and 6 - focusing lenses of the RZ range,

7 and 8 - pulse shapers that trigger (include) emitters 1 and 2,

9 - line delay for the time T _ass ,

10 - clock pulses;

FIG. 2b is a timing diagram of the operation of a block of infrared emitters;

FIG. 3 - spectral detection capabilities of the recommended photodetectors of the RD-36 and RD-43 series;

FIG. 4a is a simplified block diagram of an IR receiver,

where 11 is the photodetector of the RD-36 or RD-43 series,

12 and 13 - amplifiers of the output signals of the photodetector (closed in the initial state),

14 and 15 - electronic keys, unlocking amplifiers 12 13 synchronously with the arrivals at their input of the signals of the photodetector,

16 is a clock generator with a frequency of FT (repetition period T _t ),

17 is a diagram for comparing output signals from amplifiers 12 and 13,

18 - amplifier differential signal from the comparison circuit,

19 is an indicator block indicating the measured level of toxic gas concentration in a controlled volume;

FIG. 4b is a timing diagram of the operation of the receiver unit.

The possibility of practical implementation of the proposed method is further justified by examples of a mixture of hydrocarbons with air. The lower explosion limit for such gases is ~ 2%, that is, at atmospheric pressure, the addition of these gases (from methane to butane) in an amount of 0.02 atm is considered dangerous, as indicated [8, 9].

The proposed method is based on the following source data:

- the absorption coefficient of infrared radiation α hydrocarbons ranges from 7 cm ^-1 ATM ^-1 to 23 cm ^-1 ATM ^-1 , which allows you to use the average absorption value for calculations - 15 cm ^-1 ATM ^-1 [10];

- the absorption of IR radiation obeys the Bouguer-Beer law [11] of the form

where P _about and Ρ - respectively, the power of the IR radiation source and the power of this radiation at a distance L from the source.

Table 1 shows the calculated values of the ratio P / P _about at various values of α and L, while the hydrocarbon content in the air is expressed in% and in pressure. Note that the content of combustible gases in the air is 0.2% (2 · 10 ^-3 atm), 10 times less than the explosive level, the content equal to 0.02% (2 · 10 ^-4 atm) is 100 times less explosive level and the content of 0.002% (2 · 10 ^-5 atm) - 1000 times less than the explosive level, which corresponds to their normal content in the atmosphere.

Table 1 Hydrocarbon content in the air % 0.002 0.02 0.2 atm 2 · 10 ^-5 2 · 10 ^-4 2 · 10 ^-3 L = 50 cm 1.5 · 10 ^-2 0.15 1,5 α · L 100 cm 3 · 10 ^-2 0.3 3.0 200 cm 6 · 10 ^-2 0.6 6.0 L = 50 cm 0.99 0.8607 0.2231 R / R _about 100 cm 0.97 0.7408 0,0498 200 cm 0.94 0.5480 0,00248

From table 1 it follows that with increasing distance of transmission of IR radiation in air L, the ratio P / P _о decreases, which indicates an increase in power absorption in air with different contents of combustible gases.

So, at L = 100 cm, the absorption at a gas content of 2 · 10 ^-4 and 2 · 10 ^-5 atm is 0.26 P _about and 0.03 P _about , respectively. Of course, the first value of the absorption of IR radiation is much simpler to register if P _o is of sufficiently great importance.

Thus, it is advisable to consider the distance L between the IR meter and the IR receiver when implementing the proposed method in a portable embodiment of at least 100 cm.

As IR emitters, the authors propose using small-sized high-speed semiconductor IR emitters IL 151 A series developed and manufactured at the enterprise of the Scientific Research Institute “Girikond” (St. Petersburg) based on fractally structured nanocomposite films of lead solenide and solid solutions based on it.

The spectral characteristics of the proposed IR emitters are shown in FIG. 1, and the characteristics of the radiation sources in table 2 (from [12]).

table 2 Technical specifications Units rev. IL 151 A-B IL 151 A-D Maximum radiation wavelength μm 3.4 3.00 The width of the radiation spectrum (at the level of 0.5) μm 0.5 0.5 Radiation power
(continuous mode) mW 0.16 0.16 Radiation Power (Pulse Mode) Tue 1,2 1,2 Direct forward voltage AT 10 10 Direct forward current BUT od 0.1 Pulsed Forward Current BUT 2.0 2.0 Goodness 200 200 Pulse duration ISS one hundred one hundred Rise (fall) time
pulsed radiation ISS 10 10

The radiation wavelength corresponding to the maximum radiation (i.e., photoluminescence) is in direct proportion to the semiconductor material and the method of manufacturing the emitting film. From FIG. 1 and Table 2 it follows that for the proposed method it is necessary to use a radiator IL 151 A-B with a concentration of CdSe in a solid solution of Pb _1-x Cd _x Se equal to 10% for a working wavelength λ _slave = 3.39 μm, and a radiator at λ _opt = 3.0 μm with a CdSe concentration of 20%. Since the width of the absorption spectrum of toxic gases averages 20–60 nm [10, 13], the recommended emitter for λ _slave must be equipped with an optical interference filter that “narrows” the emitted spectrum (without a filter, the half-maximum spectrum is 500 nm from Table. 2). The filter is a 380 μm thick silicon wafer with a double-sided multilayer optical coating. The width of the spectrum of a narrow-band interference filter is 40 nm with a transmission of at least 0.7.

It is also proposed to install a similar narrow-band filter at 3.0 μm with an emitter bandwidth of 40 μm and a transmittance of at least 0.7 on an IR emitter on λ _supports , which will greatly simplify the adjustment to zero of the measuring system.

Important in the implementation of the method is the ability to manufacture the mentioned filters by special order at the same enterprise "Girikond".

The full angle of IR radiation in the devices of the IL 151 A series can be taken equal to 40 ° by analogy with other IR emitters manufactured in the KT-2 package (see [12]) of the Girikond enterprise.

At the recommended distance of the RF emitters - the IR receiver L = 100 cm and the radiation angle of 40 °, the emitters form a spot with a diameter of ~ 73 cm in the plane of the receiver. For example, when the receiving area of the receiver is ~ 4 · 10 ^-2 cm, it receives radiation ~ 10 ^-5 of the radiating power R _about . Taking into account other losses R _о , which will be indicated below, the need for focusing on λ _slave and λ _οpor is mandatory. In the proposed method, size of focused infrared radiation in _rad D λ and λ _{slave supports} recommended bind to the size of the infrared receiver window of the input D, _etc., and the expression for this connection will be offered hereinafter.

Thus, each emitter should also be equipped with a focusing germanium lens [11]. In this case, both emitters on λ _slave and λ _supports are located next to each other (possibly touching the housings), but the following is essential for the design of the device that implements the proposed method - the axis of the emitters and radiation is directed to the center of the IR receiver. To simplify the implementation of this requirement, it is proposed that the IR emitters and the IR receiver be placed on a single rigid support with structural elements that, when exchanging receivers and emitters, ensure that this requirement is met.

As follows from table 2, the maximum radiation power allows you to implement a pulsed radiation mode, which is recommended by the authors.

In FIG. Figure 2a shows a block diagram of pulsed IR emitters, where 1 and 2 denote emitters for λ _slave and λ _impulse , which are equipped with narrow-band optical filters 3 and 4 and focusing lenses 7 and 8. Radiators 1 and 2 include pulse shapers 7 and 8, which are triggered by clock pulses from a generator. To temporarily shift the radiation pulses by λ _slaves and λ _{poles, the} radiation by λ _{poles is} delayed for a time T _back , for which clock pulses 10 start the pulse shaper 8 through the delay line 9. Since the recommended IR emitters should work in a pulsed mode with known characteristics (see . tab. 2), then these characteristics are working. Therefore, the radiation duration at λ _slave and λ _supports should be set equal to Δt _slave = λt _supports = 100 μs. Recommended duty cycle q = 200, the clock frequency F _{t of the} clock generator is equal to

where Τ _t is the pulse repetition period.

в связи с этим и импульс излучения может быть длительностью, меньшей 100 мкс, и скважность q может быть больше значения 200 (при этих изменениях параметры излучений не изменяются).The value of F _t may vary (for the data of table. 2

in this regard, the radiation pulse can also be shorter than 100 μs, and the duty cycle q can be greater than 200 (with these changes, the radiation parameters do not change).

с задержка Т_зад=(8÷12)·10^-3 с и при ее среднем значении Т_зад=0,5 Т_т импульсы излучения на λ_раб и λ_опор окажутся разведенными по времени и будут восприниматься ИК фотоприемником как импульс с частотой 100 Гц. Предложенный диапазон изменения задержки Т_зад связан с тем, что временной интервал между импульсами излучения меньше 0,4 Т_т (то есть меньше 8·10^-3 с), по мнению авторов, может вызвать затруднения при приеме таких импульсов фотоприемником.If the duration of infrared radiation λt _slave and λt _supports take from table. 2, the delay time T _{ass, the} authors propose equal to T _ass = (0.4 ÷ 0.6) T _t In this case, when

s delay T _ass = (8 ÷ 12) · 10 ^-3 s and at its average value T _ass = 0.5 T _{t the} radiation pulses at λ _slave and λ _supports will be separated in time and will be perceived by the IR photodetector as a pulse with a frequency of 100 Hz The proposed range of changes in the delay T _ass associated with the fact that the time interval between the radiation pulses is less than 0.4 T _t (that is, less than 8 · 10 ^-3 s), according to the authors, can cause difficulties when receiving such pulses with a photodetector.

In FIG. 2b shows the above-described timing diagram of the operation of the emitter unit. Each diagram depicts the position of the main pulses at the main points of the circuit on the time axis:

T.A - pulses of the clock generator,

tV - clock pulses delayed by T _ass and illustration of the position of the radiation pulses on λ _slave and λ _supports on the time axis.

As a radiation detector for λ _slave and λ _poles , infrared photo detectors are offered, which are manufactured by AIBI LLC (IBSG Co.Ltd) in collaboration with the IK Optical Electronics Laboratory of the Physicotechnical Institute named after A.F. Ioffe (St. Petersburg). In FIG. Figure 3 shows the spectral distributions of the detection ability of the produced photodetectors of the RD-36 or RD-43 series, in which the sensitive area is 2 × 2 mm, and the detection ability is either 5 · 10 ⁹ W ^-1 , Hz ^1/2 , cm for RD-36 or 7 · 10 ⁸ for RD-43.

The advantages of the proposed photodetectors should be considered:

- high speed

- high value of detection ability,

- room temperature work.

Since the photodetectors of the indicated series, made in the TO-5 or TO-8 package, have an external size of 1 ÷ 2 cm (this is the size D _pr ), it is proposed to install focusing radiation spots on Δ _slave and λ _{supports with a} diameter D _rad in the zone of the IR photodetector expression

For example, when D _CR = 1 cm, the spot D _rad should not exceed 5 cm.

The radiation power that affects the photosensitive element of the photodetector with an area of 4 · 10 ^-2 cm ² when receiving pulsed IR radiation at λ _slave and λ _supports is determined from the expression

where P _o - radiation power; Κ ₁ - transmittance λ _slave and λ _supports narrow-band optical filters (K ₁ = 0.7); K ₂ - transmittance of radiation by a focusing lens (K ₂ ≅ 0.35); K ₃ - coefficient taking into account the receiving area and the size of the radiation spot in the area of the IR receiver (for example, when D _rad = 5 cm, Κ ₃ = 5.1 · 10 ^-4 ); K ₄ - coefficient taking into account a possible increase in the width of the radiation spectrum by λ _slave and

λ_supports, equal to 40 nm, and the true width of the absorption of hydrocarbons (take K_four≅0.5).

Substituting the initial values of the coefficients at Ρ _ο = 1.2 · 10 ^-3 W, the power ΔΡ _pr at the receiving element of the photodetector turns out to be ~ 7.5 · 10 ^-8 W, which is an order of magnitude higher than the detecting ability of the RD-36 photodetector and, therefore, provides reliable registration of pulsed radiation at λ _slave and λ _supports

In the proposed method, the presence of combustible gases in a controlled space is detected and their concentration is determined after zero is established on the reference scale. This zero is set when there are no toxic gases in the controlled zone, and the output signals of the photodetector from pulses to λ _slave and λ _supports are equal to each other. In the comparison circuit, these signals must arrive simultaneously, for which the output signal from λ _slave should be delayed by the same delay time T _back .

Thus, the following operation of the IR receiver unit is proposed, the conventional circuit of which is presented in FIG. 4a. In FIG. 4a, under 11, an RD-36 series photodetector is presented, the output signals of which are fed to two amplifiers 12 and 13, which are closed at the input in the initial state. The amplifiers are opened synchronously with the receipt of the output signals of the photodetector by electronic keys 14 and 15, which are triggered by clock signals from the clock generator 16 with a frequency F_t. In this case, the clock signals to the electronic key, which open the amplifier on λ_supports, served through the delay line 9, i.e. delayed by time T_ass. Electronic keys open amplifiers for a time equal to 0.9Δt_pa, i.e. delayed by 0.1Δt_slave pulses of electronic keys 14 and 15 relative to the moment of arrival of the output signals of the photodetectors on the amplifiers. Such a delay, according to the authors, is necessary to exclude the influence of transients in the input circuits of amplifiers 12 and 13 when the leading edge of the output signal of the photodetector arrives at the operation of the comparison circuit 17.

The simultaneous receipt of the output signals of the amplifiers in the comparison circuit is provided by the inclusion in the amplifier circuit on the λ _slave delay line 9 for the time T _ass . The difference signal from the comparison circuit is amplified by the amplifier 18 to the level that is necessary for the indicator unit 19, which forms a scale for measuring the concentration of detected combustible gases.

The timing diagram of the operation of the receiver unit is shown in FIG. 4b, where each diagram depicts the position of the main pulses at the main points of the circuit on the time axis: t. Ρ - output pulses from the photodetector, t. Ε - clock pulses of the clock generator 16, t. F, etc. Μ - respectively, the pulse of the electronic key 15, opening the amplifier on λ _supports 13 and the output signal of the amplifier 13, t. N is the output signal of the amplifier on λ _slave 12, t. Ρ is the difference signal at the output of the comparison circuit (18). The circles in the diagrams in an enlarged form show a time offset of 0.1Δt _pab relative to the arrival of the photodetector signals (tD) of the electronic key pulses opening the amplifiers 12 and 13 for the time Δt _slave .

The maximum output signal at the output of the comparison circuit 17 is obtained when one of the emissions at λ _slave or at λ _{supports is} absent. As already noted, in the absence of combustible gases, zero concentration measurement scales are determined when the radiation power is equal to λ _slave and λ _supports and the output signals from the photodetector are equal, the characteristics and characteristics of amplifiers 12 and 13 are identical.

If, when registering a concentration of combustible gases of 46% or 26% of the maximum value, it is not difficult for specialists in the field of electronic circuitry, then registering concentration levels of 3 ÷ 5% is difficult.

It is proposed to record and measure such low concentrations by limiting the total recording time to T _sis , which is proposed to be determined from the expression

where Ν is the number of pulses from the comparison circuit carrying information on the presence of combustible gases. For example, if you set the number of such pulses N = 200, then the total time T _sis = 2 s. In this case, the comparison scheme should be equipped with the function of accumulating the difference signal. Similar accumulations are used in analog television, when horizontal sync pulses are accumulated in a capacitive storage (through a diode key) to a value that corresponds to the frame scan time and when it is turned on by the accumulation time. The determining condition for the accumulation of the difference signal in this way is the stability of the operation of IR emitters, amplifiers of the photodetector signals and their thresholds that determine the zero value of the reference scale.

The proposed pulse mode of operation, the time limit for measuring low levels of toxic gas concentration T _sys , the time limit for the operation of amplifiers of the output signals of the photodetector Δt _slave , according to the authors, will allow the registration of toxic gases with a concentration of 2 ÷ 10 ^-5 atm.

Comparison schemes, difference signal amplifiers, and a unit for generating information on the content of combustible gases (elements 17, 18, and 19 in Fig. 4a) for their content up to 2 · 10 ^-4 atm can be borrowed from existing gas analyzers indicated in [1 ÷ 6 ]. To measure toxic gas concentrations up to 2 · 10 ^-5 atm, methods and circuits that are used in the study of far space associated with the registration of photons and the accumulation of these signals under signal-to-noise conditions are less than unity can be recommended.

The advantage of the proposed method should be considered the achievement of the specified technical result, namely:

- registration and measurement in a controlled space of low levels of toxic gases of the hydrocarbon group from 2 · 10 ^-4 atm (100 times lower than the explosive level) to 2 · 10 ^-5 atm (1000 times lower than the explosive level, which practically corresponds to the normal presence of combustible gases in the atmosphere);

- low weight and dimensions of the device that implements the proposed method;

- the identity of the emitters and focusing lenses on the λ _slave and λ _supports ;

- the identity of the pulse shapers, signal amplifiers of the photodetector, electronic keys, opening amplifiers, delay lines on the T _ass .

Thus, according to the authors, a method for detecting combustible gases long before the formation of an explosive mixture with air and toxic gases long before the formation of life-threatening concentrations is proposed.

References

1. P.I. Bresler "Optical absorption gas analyzers and their application" - L .: "Energy", Lenin., Department, 1980.

2. "Gas analyzers - leak detectors of combustible gases, natural gas", production and commercial group "Granat", http://granat-e.ru/catalog-gtggpg.html; E-mail: mailto: marketing@granat-e.ru.

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4. A.G. Zavadovsky, I.I.Plyusnin, S.N.Sysoev “Small-sized laser locator for methane leaks”, “Sensors and Systems” magazine, Chelyabinsk OUNB, No. 4, 2007 (UDC 621.018.8656.56, BBK 31.32 + 39.7).

5. “Gas analyzers” - “Radical”, Voronezh, http://www.radicom.ru/c237-gazoanalizatory.html.

6. “Gas analyzers DVK hydrocarbons” - “ANALITPRIBOR”. RU. G. Smolensk. http: //www.analitpribors.ra/gazoanalizatory-dvk-uglevodorodov. html

7. A.O. Vasiliev, V. G. Shenanin, P. V. Chartiy “Infrared detector for measuring the concentration of toxic gas molecules in the air flow”, patent No. 2484450, G01N 21/35 from 11.24.2011, publ. 06/10/2013, bull. No. 16.

8. GOST 12.1.011-78 ^∗ , reissued and approved on 06.1988 (IUS-5-82, 10-88).

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Claims (2)

1. A method for detecting microconcentrations of combustible and toxic gases, which includes the operation of transmitting two infrared (IR) radiation, close in value, to the working λ _slave and the reference λ wavelength _supports through a controlled volume in which combustible or toxic gases are absorbed by λ _slave , and they do not absorb the _supports on λ, while the output signals of the IR receiver, which are affected by radiation on the λ _slave and λ _supports , form an information signal on the presence and concentration of gases in the processing system, characterized in that the IR radiation at lengths waves λ _slave and λ _{supports are} carried out by two semiconductor emitters, which operate in a pulsed mode and which are placed next to each other so that the axis of the emitters is directed to the center of the IR receiver, and the distance of the IR emitters - the IR receiver forms a controlled space, while both IR emitters provided with interference filters which "narrow" emission spectrum, and themselves in the plane of focus the radiation receiving this radiation so that the size of the focused radiation is set by the condition D _rad ≤5D _etc., the durations the number of radiation pulses per λ _slave and λ _supports are equal to each other, Δt _slave = Δt _supports , and the clock frequency F _t , which sets the pulse mode of operation, is set by the clock generator from the equality

in this case, the IR emitter at λ _{slave is} triggered by clock pulses from the generator directly, and the emitter at λ _{poles is} triggered by clock pulses that delay for a time in the range

and provide temporary separation of IR radiation pulses by λ _slave and λ _supports , and the output pulse signals of the IR receiver are fed to the inputs of two amplifiers that are closed at the input in the initial state and are opened synchronously with the appearance of the output pulses of the IR receiver, for which the amplifier at λ _{slave is} opened clock pulses directly from the generator, and the amplifier on the λ _supports open clock pulses that delay T _ass , while the operation time of the amplifiers is set equal to 0.9Δt _slave , and the output signals of the amplifiers are compared by the circuit Compare, for which the output signal of the amplifier at λ _slave is delayed by time T _ass where D _rad and D _ave - respectively the radiation spot on λ _slave and λ _supports in the IR receiver plane and the size of the input receiver window, T _m - repetition period of clock pulses, q - duty cycle of the pulse mode of operation. 2. The method according to claim 1, characterized in that the total operating time T _{sis is} limited in time in accordance with the expression

and the comparison circuit is equipped with a function of accumulating difference signals that occur on the period T _t , the number of which during the time T _{sis is} set equal to N.

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