SU1341554A1 - Method of location measurement of transparent media optical parameters - Google Patents

Description

The invention relates to the investigation of materials and substances by optical methods and can be used to remotely measure the optical parameters of transparent media, such as scattering and attenuation parameters of a radiated medium.

The aim of the invention is to simplify the method of measuring optical parameters of media and increasing its interference.

The drawing shows a functional diagram of the hardware implementation of the proposed method.

The device contains a source of continuous radiation 1, a modulator 2, a lens 3, a translucent plate 4, a diaphragm with a small aperture 5,. mounted in the focal plane of the lens 6, which forms the image of the air interface 7 — the medium 8 is investigated through the lens 9 to the receiver IO radiation, meter 1 phase difference, computing device 12, meter 3 amplitudes of the emitted radiation, input device 14 of smooth changes in modulation frequency.

In the study of the environment with the help of this device in the optical path is achieved weakening power at 15

20

25

thirty

F (n) F, If L (a) (, (4)

where A (n) is the Fourier transform of the function A (t,), and the phase difference between the received and emitted streams is

lsr (o) (5l), (5)

those. argument of the comlex function

A (a)

The modulation frequency fS is varied by using a modulator-controlling device 2 of a modulation frequency input device 14, the signal from which, characterizing the current frequency fi, is fed to the computing device 12. The meter P records the amplitude F (n) and the phase difference u (.f (fi), which are also transmitted to the computing device 12. In addition, the information about the amplitude F is received from the meter 13. The calculated radiation flux is

2, -, 2

f (z) s

rfdz 1

Chit

the current angle is the FIELD of the transmit-receive system, S is the area of the entrance pupil of the lens 6, n (z) is the refractive index profile of the middle zone z is the distance traveled by the radiation in the medium. In this case, the flux of received single scattered radiation is equal to

oo

JO. . Si

After a change in the entire frequency range, the consumer device 12, where the co-body 35 O (2) / 21G, performs the inverse Fourier transform of F (j2) e, the result of which is the function After dividing it by 40

Where

(t) fF (t -tjA (tjdt, (i),

o 11 j o

 ) G (z) y (, z

Alt, j; tg ;; t-

45

shhhhh

hehr -2 | (z) (2) 50

the impulse transfer function characterizing the optical parameters of the medium, and the air layer can be considered part of the inhomogeneous medium; F (., (T) is the probe radiation flux, c is the speed of light, the quantities G (z), () (z) are profiles of the corresponding parameters. Along the sounding path, t is the time

(t) 8 is the imbued value of Fg and the known factor cco / 8-h, we obtain the desired function A (t).

Measurements are more preferably conducted for layered media, where the elimination of ambiguity of the sounding path is achieved by choosing the sounding direction normal to the surfaces of the layers.

The increase in noise immunity in the proposed method in comparison with the impulse method is achieved due to the fact that F (sj) ider (yy) are interconnected by the Hilbert transform. Thus, the redundant information obtained as a result of measurements according to the proposed method can be used to reduce the effect of noise on the accuracy of measurements using a special algorithm implemented

t is the integration variable, and z is determined from the equation

.M 1gsh: -

If the probing flux Fjj (t) is harmonically modulated and has an amplitude of Fg, then the flux of received radiation also varies harmonically with time with the same frequency and amplitude

F (n) F, If L (a) (, (4)

where A (n) is the Fourier transform of the function A (t,), and the phase difference between the received and emitted streams is

lsr (o) (5l), (5)

those. argument of the comlex function

A (a)

The modulation frequency fS is varied by using a modulator-controlling device 2 of a modulation frequency input device 14, the signal from which, characterizing the current frequency fi, is fed to the computing device 12. The meter P records the amplitude F (n) and the phase difference u (.f (fi), which are also transmitted to computing device 12. In addition, information about the amplitude F is received from meter 13. Computing device 12, after changing l in the entire frequency range 5 O (2) / 21G, performs the inverse transformation the Fourier transform of F (j2) e, the result of which is the function After dividing it by

five

0

five

(t) 8 is the imbued value of Fg and the known factor cco / 8-h, we obtain the desired function A (t).

Measurements are more preferable to conduct for layered media, where the elimination of ambiguity of the sounding trajectory is achieved by choosing the sounding direction normal to the surfaces of the layers.

The increase in noise immunity in the proposed method in comparison with the impulse method is achieved due to the fact that F (sj) ider (yy) are interconnected by the Hilbert transform. Thus, the redundant information obtained as a result of measurements according to the proposed method can be used to reduce the effect of noise on the accuracy of measurements using a special algorithm implemented

computing device 12 and determined in accordance with the specific situation of measurement, depending on the presence and properties of certain noise.

Claims (1)

Invention Formula A method for locating measurement of optical parameters of transparent media, including the formation of probe radiation, its direction to the medium, reception of backscattered radiation, determination of the impulse transfer function of the medium, according to which optical parameters are judged, characterized in that, in order to simplify the method and increase it noise immunity, form continuous probe radiation harmonically modulated in intensity with the circular frequency U, while changing the modulation frequency ry from zero to Azn (z) / 2 n c, where UZ is the required spatial resolution c is the speed of light in air; n (z) is a known refractive index profile along the direction of sounding, when receiving backscattered radiation, its power is weakened by the law , where M is the scale factor; Z is the distance traveled by the radiation in the medium, then the flux F (S2) of the received radiation and the phase difference utf (P) of the received and emitted α are measured. currents in the range of the modulation frequency, and the impulse response function A (t) is determined from the relation lzn (z) A (t) i I F (n) e t- -t da,  i where t is time; i - imaginary unit. Compiled by S. Golubev Editor E. Sligan Tehred I.Popovich Proofreader A.Ilyin P-III I 1.1. ,, |. .. --li 1. - .. - .. and .. „. Order 4430/48, Circulation 776 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4