RU1217074C - Method of determining structural characteristic of atmospheric turbulence - Google Patents

Description

I

The invention relates to the field of atmospheric optics and can be used to determine the optical and meteorological parameters of the atmosphere.

The purpose of the invention is to increase the speed, efficiency and range of measurements of the structural characteristics of atmospheric turbulence.

In FIG. 1 shows a bistatic diagram of a device for implementing the proposed method; in FIG. 2 is a monostatic diagram of said device.

The method is confirmed by the fact that the source 1 of continuous (phase 1) laser radiation directs the beam of radiation through telescopic optical system 2 at a zenith angle b through layers of a turbulent atmosphere of length .L into the scattering volume 3 under study, length 1, where the beam is scattered by aerosol particles and, returning back, enters the receiving system 4. In the focal plane of the receiving lens, a photodetector of the random image displacement measuring device 5 is mounted.

According to the obtained data, taking into account the radius of the transmitted radiation beam a, zenith angle .0 of the sensing path and exceeding the height And of the scattering volume under study above the height of the radiation source, the values of the sought parameter are judged.

In the monostatic roving circuit (FIG. 2), the pulsed source 6 sends, using an optical system 7, the radiation to the scattering volume 3. The backscattered radiation is incident on the beam splitter plate 8 and on the receiver of the random image displacement measuring device 9, according to which it is judged about the investigated parameter.

When a collimated laser radiation is sent to the atmosphere under study and the backscattered radiation is received, the received light flux through the lens of the receiving system is determined by the flash

. at.

e

(1)

where the value coincides with the dispersion of random displacements of the image of the scattering volume

21707A

distance b from the radiation source, and 6 determines the variance of random displacements of the image of an extended incoherent source, the sizes of 5 of which coincide with the dimensions of the scattering volume.

The first term is due to random distortions of the phase front of the beam on the way to the scattering volume. These distortions (tilts of the phase front) cause random changes in the position of the probe beam in space as a whole, therefore, cause trembling (5th trace of the beam and the image of the scattering volume.

The second term is related to phase distortions of the wave and the path from the scattering volume to the receiving system. Thus, the jitter of the image is determined by the effects of jitter of the probe beam at a distance from the transmitter and jitter of the image of an extended incoherent source, the sizes of which coincide with the dimensions of the scattering volume.

In a bistatic probing scheme (Fig. 1) with an uninterrupted (completely coherent) laser source (Part 3, f is the beam divergence angle), expression (1) takes the form. 35i

6 Versec0Jc (t) {(l-t | HAoL (i-t | H)} dt,

 where сС 0.86 (/ QO Г Ло80; С - dsp of the scattering volume, Р d +

 ; fg- ,. the field of view angle of the receiving system, determined by the size of the field diaphragm; 9 - zenith angle of the track; d is the diameter of the receiver; С1о radius of the sprinkled laser beam; C (t) is the structural characteristic of the exponent of atmospheric turbulence; And - conversion of the test volume over the radiation source; t- variable

50 integration. .

In this sounding scheme, the scattering image of the bulk volume is an extended luminous filament with a longitudinal size equal to

55 F / L. , and cross-section m - Р, / ,,, where F is the focal distance of the receiving lens, and E.,. Measuring the value of dispersion b | (B) for discrete

As the height of the scattering volume above the underlying surface bj (j 1,2, ..., h) is set, the altitude profile is restored from the integral equation.

At Р ОО (the longitudinal size of the scattering volume is much larger; transverse) due to the averaging of phase fluctuations, over an extended non- coherent dispersion source 6, it becomes small compared to δ (σ1 «1), therefore, a term of the form (1 -t / H) in the integrand in the formula (2) can be neglected. In this case, the integral equation for determination takes the form

10

-.2

 f5

C nc.)

 ftch (P o) and formula (2) takes in

p (h) Ma «s c0JcJ) ri-l / H) dt. (3)., 4 -1/3 r% ,, f.,, G. about bf--. o „secв C a). (-) o.ier

E case of low flow rate. bunch, when the average beam size at a distance L from the emitter p ,, ((.) remains close to its initial size, i.e.; (L) - o, the dispersion of the trembling image of the beam trace in the scattering medium ery and parameter C, connected by simple-to-linear (buo "C) relations of the form (2), GB).

In other cases, when PbCb), or Pj (bond b and e becomes non-linear.

With a monostatic design, a roving probe, i.e. in the case of a pulsed source (figure 2), the value of E sov decreases with the size of the probing pu (C Od) and the formula (2) takes

The choice of a type of radiation that is slightly divergent (U 3) as the probe beam allows an increase in the accuracy. Bone, Measurement irrelevance C, and sensing range.

(P o) and formula (2) takes in

., 4 -1/3 r% ,, f.,, G. bf--. o „secв C a). (-) o.ier

E case of low flow rate. beam, when the average size of the beam at a distance L from the emitter p ,, ((.) remains close to its initial size, i.e.; (L) - o, dispersion. shaking image of the beam trace in the scattering medium is ep and parameter C, are connected by simple-to-linear (buo "C) relations of the form (2), GB).

In other cases, when PbCb) or Pj (connection b. And e becomes non-linear.

With a monostatic sounding scheme, i.e. in the case of a pulsed source (figure 2), the value of E coincides with the size of the probe beam (C Od) and formula (2) takes the form

: K () - t (W) dt} CM

The length of the volume is scattered and simple. The apparent resolution is determined by the pulse duration.

Compiled by S. Nepomnch. Editor N. Zagrebelna Tehred T. Dubinchak Co-rector L. Pilipenko

Order 1090 Run

VNII1Sh of the USSR State Committee

for affairs of inventions and discoveries 113035, Moscow, Zh-35, Rauska nab., 4/5

 Branch PSh1 Patent, Uzhgorod, Project 4,

FIG. 2

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