RU75761U1 - ACOUSTOPTIC RADIO SIGNAL METER - Google Patents

Abstract

The proposed utility model relates to radio measurement technology and can be used as a high-precision meter of radio signal parameters in broadband communication, radar and direction finding systems. The technical result, which consists in increasing the accuracy of measuring the spectral characteristics of radio signals while achieving high compactness of the meter, is achieved by the fact that in the acousto-optic meter of parameters of radio signals containing a laser, a collimator, AO deflector sequentially located in the light, the measured radio signal being integrated into the electrical input of the optical system, which integrates the optical system , a recording device, in the direction of diffracted laser radiation between an acousto-optical deflector and a recording device instead of a single-component integrating optical system includes an optical system with a positive (focus F ₁ ) and negative (focus F ₂ ) lens with an equivalent focus F _equiv . Moreover, F _equiv , F ₁ , F ₂ and the distance d between the lenses are related by the conditions: and the recording device is installed at a distance of 2d from the positive lens.

Description

The proposed utility model relates to radio measurement technology and can be used as a high-precision meter of radio signal parameters in broadband communication, radar and direction finding systems.

A well-known (see figure 1) acousto-optical (AO) analyzer of the spectrum of microwave radio signals (Belokurova OI, Petrunkina V.Yu., Scherbakova OV A.S. No. 1354128, published 11/23/1987 in the bulletin No. 43), which includes a laser 1, a collimator 2, connected in series over the light, forming an optical cascade of the transition from a laser beam to a plane light wave of a given aperture, AO deflector 3, to the electrical input of which a measured radio signal is supplied, which integrates the lens 4, which carries out the Fourier -transformation, in the focal plane of which is located p gistriruyuschee device 5.

Signs of an analogue that coincide with the signs of the proposed utility model are a laser, a collimator, an AO deflector, an integrating lens (optical system in the claimed device) and a recording device that are sequentially turned on by light.

The reason that impedes the achievement of the technical result is the limited focal length of a single integrating lens with the dimensions of the system unchanged.

Also known is the acousto-optical receiver-frequency meter described in the invention by V.V. Rozdobudko, V. A. Malyshev, G. G. Chervyakov, RF patent No. 2142140 with priority dated 01/30/98, published on 11/27/99 in bulletin No. 33, which contains a laser light source 1 sequentially located along the light with an amplitude modulator and a first modulating voltage source, a collimator 2 and AO deflector 3 with an integrating lens 4, a second source

modulating voltage loaded on a position-sensitive photodetector 5 with a set of differential frequency amplifiers (see figure 2).

Signs of an analogue that coincide with the features of the proposed utility model are a laser light source, a collimator, an AO deflector, an integrating lens (optical system in the inventive device) and a position-sensitive photodetector (recording device in the inventive device), sequentially switched on by light.

The reason that impedes the achievement of the technical result is the limited focal length of a single Fourier lens with constant dimensions of the system.

The closest in technical essence to the claimed device is a device - prototype: acousto-optical spectrum analyzer with spatial integration (published in the book: Optical processing of radio signals in real time / O.B.Gusev, S.V. Kulakov, B.P. Razzhivin, D .V. Tigin: Edited by S.V. Kulakov - M.: Radio and Communications, 1989, p. 48).

The prototype device (see Fig. 3) contains a laser 1, a collimator 2, AO deflector 3, sequentially located around the world, and a measured radio signal, an integrating lens 4 and a recording device 5, is supplied to its electrical input.

The signs of the selected prototype, common with the claimed utility model, are a laser, a collimator, an AO deflector, which are connected in sequence by light, to the electrical input of which a measured radio signal, an integrating lens (optical system in the inventive device) and a recording device are supplied.

The reason that the prototype cannot achieve the required technical result is the limited focal length of a single integrating lens with the dimensions of the system unchanged.

The primary concern when choosing an integrating optical

The system in the circuit of the radio signal parameter meter is matching the linear dimensions of the multi-element recording device in the diffraction plane with the working frequency range. At the same time, the dimensions of a multi-element recording device (the number of its elements involved) determine the accuracy of measuring the frequency of radio signals, to increase which it is necessary to use a recording device with a large number of elements, which in turn requires an increase in the focal length of a single integrating lens (a single-component optical system), which determines the dimensions the whole system. So in such a scheme, the need to achieve the required compactness of the meter imposes restrictions on the magnitude of the accuracy of the frequency measurement.

The task to which the proposed utility model is directed is to remove restrictions on the magnitude of the focal length of the optical system while maintaining the compactness of the acousto-optical meter of radio signal parameters.

The technical result is achieved in that, in the direction of the diffracted laser radiation between the acousto-optical deflector and the recording device, instead of a single-component integrating optical system, a two-component optical system is included, characterized by an equivalent focus F _eq and consisting of a positive lens with a focus F located at a distance d from each other ₁ and a negative lens with focus F ₂ , and the values of F _EQ , F ₁ , F ₂ and d are related by the relations: and the recording device is located relative to the positive lens at a distance equal to 2d .

To achieve a technical result in an acousto-optical meter of radio signal parameters, containing a laser, a collimator, an AO deflector, sequentially located around the light, on an electric

the input of which is a measured radio signal that integrates the optical system and the recording device, in the direction of the diffracted laser radiation between the AO deflector and the recording device, instead of a single-component integrating optical system, a two-component optical system is included, characterized by an equivalent focus F _eq and consisting of each other sequentially separated by distance d from a friend of a positive lens with focus F ₁ and a negative lens with focus F ₂ , and the values of F _equiv , F ₁ , F ₂ and d are related by the relations: and the recording device is located relative to the positive lens at a distance equal to 2d , where F _equiv is the equivalent focus of the optical system, F ₁ is the focus of the positive lens, F ₂ is the focus of the negative lens, d is the distance between the positive and negative lenses.

Comparing the proposed device with the prototype, it is clear that it contains new features, i.e. meets the criterion of novelty. Carrying out a comparison with analogues, it is seen that the proposed device meets the criterion of "significant differences", since no new features are revealed in the analogues.

To prove the presence of a causal relationship between the claimed features and the achieved technical result, we consider the principle of operation of the proposed acousto-optical meter of radio signal parameters and compare it with the work of the prototype and analogue.

The essence of the proposed utility model, as well as the operation of the inventive acousto-optical meter of the parameters of the radio signals is illustrated in figure 4. The device incorporates sequentially located throughout the world: laser 1, collimator 2, AO deflector 3, to the electrical input of which a measured radio signal is supplied, a two-component integrating optical system consisting of a positive lens 4

with a focal length F ₁ and a negative lens 5 located at a distance d from it; with a focal length F ₂ installed between the AO deflector 3 and a recording device 6, which is located relative to the positive lens 4 at a distance Z ₀ .

From the geometric theory of optical systems it is known that the equivalent focal length of a two-component optical system is determined by the relation F _equiv = F ₁ F ₂ / (F ₁ + F ₂ -d). Moreover, the image of such a system is built at a much smaller distance than that of a single lens with the same focus, and if this distance from the positive lens 4 to the recording device 6 is counted, it is determined by the expression Z ₀ = F ₁ -F ₂ (F _equiv / F ₁ + F ₁ / F _eq -2) .

The graphs of the dependence of the dimensionless quantity (Z ₀ / d) on the focal length F ₁ for various F _{2 are} presented in Fig. 5, which shows that the curves have a minimum equal to two at a certain (optimal) value of F _1, which can be determined from the condition δ (Z ₀ / d) / δ (F ₁ ) = 0 : . For this optimal case, when the meter has maximum compactness, we can obtain an expression for the distance between lenses 4 and 5: .

The proposed acousto-optical meter of the parameters of the radio signals works as follows. The measured radio signal is fed to the input of the AO of the deflector 3 (see Fig. 4), in the light and sound duct of which, due to the inverse piezoelectric effect, it creates internal periodic deformations of the medium (acoustic waves). The optical radiation from the laser 1, passing through the collimator 2, at a certain angle to the front of the acoustic field falls on the periodic structure propagating in the light and sound duct. As a result of acousto-optical interaction, according to the known laws of diffraction, at the output of the AO of the deflector 3, the diffracted beam deviates from the transmitted beam by a certain angle.

This angle changes when the frequency of the radio signal deflector 3 supplied to the AO changes. In the operating frequency range, the diffracted beam scans in an angle and covers a predetermined area on the recording device 6. Coordination of the movement of the diffracted beam during angular scanning at the exit of the AO deflector 3 with the specified area on the recording device 6 is provided by a two-component optical system consisting of a positive lens 4 with a focal the distance F ₁ and the negative lens 5 with a focal length F ₂ . Due to the inclusion between the AO deflector 3 and the recording device 6 of such a two-component system with a common (equivalent) focal length F _equiv = LV / λ ₀ Δf ( L is the length of the active region of the recording device, V is the ultrasound velocity in the crystal of the AO deflector, λ ₀ - the valley of the laser radiation wave, Δf- band of operating frequencies of the AO meter), the focus of the positive lens and distance between components the dimensions of the AO meter are reduced, which are determined by the distance ( 2d ) from the lens 4 to the recording device 6, which, compared with the meter circuit containing a single-component integrating optical system with a focus equal to F _equiv , is reduced by 0.5 F _equiv / d times. Information about the distribution of radiation intensity on the recording device is displayed for subsequent processing (see figure 4).

Consider an example. Suppose that to achieve a given accuracy of frequency measurement in the band Δf = 500 MHz, a recording device with a photodetector size (in the diffraction plane) of 10 μm and an amount of 5000 is required, so L = 50 mm. When using an AO deflector with V = 3590 m / s and a laser with λ ₀ = 657 nm, we find that the optical system should have a focal length F _equiv = LV / λ ₀ Δf = 546 mm. According to the well-known F _equiv , setting the focus of the negative lens of the two-component system

F ₂ = -20 mm, we find that the focus of the positive lens is mm, and the distance between the lenses mm

For the given example, when using a two-component integrating optical system, the distance between the optical system and the recording device is 0.5 F _equiv / d = 3.16 times less than when using a single-component integrating optical system.

Thus, the scheme of the proposed acousto-optic radio signal parameter meter with a two-component integrating optical system installed between the AO deflector and the recording device provides better compactness with the same frequency measurement accuracy or, conversely, better frequency measurement accuracy with the same compactness than the scheme of the acousto-optic radio signal parameter meter with a single component integrating optical system.

Claims (1)

An acousto-optic meter of radio signal parameters, consisting of a laser, a collimator, an acousto-optic deflector located in series along the light, to the electrical input of which a measured radio signal of an integrating optical system, a recording device, characterized in that the integrating optical system is a two-component optical system, characterized by an equivalent focus F _equiv and consisting of positively sequentially located at a distance d from each other th lens with the focus F ₁ and a negative lens with a focus F _2, the value _eq F, F _1, F ₂ and d are related as follows:

and the recording device is located relative to the positive lens at a distance equal to 2d, where F _equiv is the equivalent focus of the optical system, F ₁ is the focus of the positive lens, F ₂ is the focus of the negative lens, d is the distance between the lenses.