SU1288507A1 - Photometer for checking film materials - Google Patents

Abstract

The invention relates to photometry and can be used in the chemical industry in the production of various polymeric films with optically uniform and dispersive coatings. The purpose of the invention is improving the accuracy of measurements. The photometer contains two identical sources 1, 2 of light, two identical photodetectors 3, 4, installed on different sides of the material being monitored 5. A set of beam splitters 6, 7, 8, 9 are set obliquely in the direction of radiation in front of each photodetector and each light source. Identical amplifiers 10, 11 are connected, respectively, with photodetectors 3, 4. The outputs of generator 12 are connected respectively to sources 1, 2 of light and to the control input of synchronous switch 13. Two inputs of switch 13 are connected to outputs of amplifiers 10, 11, and its four outputs are with four inputs of the computing device 14. The fifth input of the computing device 14 is connected to the source 15 of the reference voltage, and the output is the output of the photometer. 2il.j CX) 00 cd C1ig.1

Description

1 1288507

The invention relates to a phototransmitter not directly from either 3 of them, but not the same as the ones on the right.

It can be used in the chemical industry in the production of various polymer films with optically homogeneous and dispersive coatings.

The purpose of the invention is improving the accuracy of measurements.

The figure shows the functional diagram of the photometer; figure 2 - Scheme of operation of the photometer when monitoring optically inhomogeneous light-scattering materials.

The photometer contains the first and second identical sources 1 and 2 of light, the first and second identical photoreceivers 3 and 4, installed on different sides of the Controlled Material 5, four beam splitters 6-9, mounted obliquely in the course of the radiation in front of each photoreceiver and each light source, the first and the second identical amplifiers 10 and 11, whose inputs are connected respectively to the first and second photodetector 3 and 4, generator 12, whose outputs are connected respectively to the source 1 and 2 of the light and to the control input of the synchronous switch 13, two inputs are connected respectively to the outputs of amplifiers 10 and 11, and four of its outputs are connected to four inputs of the computing device 14, the fifth input of which is connected to the source 15 of the reference voltage, and the output is the output of the photometer.

Photometer. works in the following way.

When measuring the optical density D with a single photodetector

Ueb. ()

(one)

where h is the distance from the plane of the photodetector to the material under test; Ah is the change in this distance.

The power pulses from the respective outputs of the generator 12 are alternately fed to the first and second sources 1 and 2 of light. In the time when the first light source emits, the radiation from it using a beam splitter 6 is divided into two beams, one of which, having passed through the beam splitter 8, hits the photo

five

0

five

0

five

the receiver 4 and the other beam, having passed through the controlled film 5 and reflected from the beam splitter 7, hits the photodetector 3. In the next period of time, when the second light source emits, the radiation from it is also split by the beam splitter 9 into two beams, one of which, having passed through the beam splitter 7, hits the photodetector 3, and the other beam, passes through the controlled film and being reflected from the beam splitter 8, hits the photoreceiver 4. As a result, the photodetectors 3 and 4 have pulse sequences that amplifiers 10 and 11 are loaded from the output of which signals are taken, whose amplitudes depend not only on the parameters of light sources, photodetectors, optical and electrical circuit elements, but, in the case of monitoring optically inhomogeneous light-scattering film materials, and on the position of the film in the measuring gap (figure 2). since in this case the radiation passing through the monitored material undergoes scattering and propagates at different angles to the material surface, as a result of which the aperture angles of the photodetectors change as the position of the monitored material changes, which leads to a change in the radiation fluxes falling on photodetectors.

Taking into account these factors, the amplitudes of the signals on the photodetectors can be written as follows:

U, I.K, sS, K ,,; U, I, .- r, K, S, T-c /., K ,,;

Ii K. t.S, K, „; and,, K; S, TOI, K,

(2)

where Uj, are the amplitudes of the pulses at the photoreceivers 3, 4, caused by the radiation beams from sources 2 and 1, reflected from the beam splitters 9 and 6, and which hit the photo receivers directly without interacting with controlled materials;

Uj5 and are the amplitudes of the pulses caused by radiation beams from sources 1 and 2 that have passed through the control sample;

I,, I, j is the radiation intensity of the light sources I and 2;

Sj, S - sensitivity of photodetectors 3 and 4;

K, K, - transfer coefficients of amplifiers 10 and II;

. and.6.

- with

-7 8 -9

responsibly reflection coefficients

and passing the beam splitters 6-9;

T - the transmission of the controlled film;

d, d is a parameter characterizing the aperture angles of the photodetectors 3 and 4 (figure 2),

The signals taken from the outputs of amplifiers 10 and 11 are fed to the corresponding inputs of a synchronous switch, to the control input of which clock pulses are supplied from the corresponding output of generator 12. After the switch, each of the four signals and °, Uj, U / and U enters the computing device 14, on p

the input of which from the reference source 15 receives the voltage U. In computing device 14, the following transformation function is performed:

and ° and;

+ and „

3 4

(2) in

(3), we get

C

Bbtx

- igt

With equal removal of the photodetectors from the controlled film and at small aperture angles (Fig. 2), we can

I

 h

h is the distance from the film to the photodetectors, and at is the linear size of the receiving area of the photodetectors. If the controlled material is shifted relative to the average position on the vein, write down that - where

The mask db, otj and o (written as follows:

h + uh

d,

h - lb

Substituting (5) into (4), we get

and 1 „1СК21аКа% р п Vx

b

- Ig t + and

oh

Taking into account that the parameters of the beam splitters, the linear size of the photodetectors and the distance between the photodetectors are constant over time,

fO

five

the value of the reference voltage U of the condition

- 18 K, T, Kt b

(7)

 67 h

Substituting (7) into (6) and taking into account that Ig T –D, where D is the optical density of the material being monitored, we obtain:

and

howled

 2 D-Hg (1 -) - (8)

15

20

25

thirty

35

40

From a comparison of the last expression with CO it follows that the influence of the movement of the material under test in the proposed photometer is an order of magnitude lower than that known, which improves the measurement accuracy. In this case, there is no effect of the parameters of the light sources of photodetectors, which also contributes to an increase in the measurement accuracy.

Claims (1)

Invention Formula A photometer for monitoring film materials containing a computing device and a light source along which a beam splitter is installed on one side of the material being monitored and a first photodetector is on the other hand, a second photodetector is installed on the second optical output of the beam splitter, and amplifiers are respectively connected to the photodetector outputs that, in order to improve the measurement accuracy, three additional beam splitters, an additional light source, a synchronous switch, were introduced into it, source 45 50 the name of the reference voltage and the generator, the outputs of which are respectively connected to the light sources and to the control input of the synchronous switch, two inputs of which are connected respectively to the outputs of the amplifiers, and its four outputs - to the inputs of the computing device, the fifth input is connected to the source of the reference voltage and the output is the output of the photometer, and the first additional beam splitter is installed in front of the second photodetector, with the second optical output of the co-optically coupled additional beam splitter 5 12885076 A light source, installed with a slit of the second and third additional opposite sides of the controlled beam splitters, with the first photodetector material and optically coupled by a source. sh Editor A.Vorovich Compiled by A. Churbakov Tehred M. Khodanych Proofreader L. Pilipenko i Order 7797/38 Circulation 799 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. / 5 .. Production and printing company, Uzhgorod, Projecto st., 4. .2