SU1476325A1 - Telephotometer - Google Patents

Abstract

The invention relates to photometry and is intended to measure the viscosities of objects and backgrounds, the differences in their viscosities and the contrast between object and background in field and laboratory conditions. The purpose of the invention is to improve the accuracy of measuring contrasts between an object and a background. The telephotometer represents a two-channel opto-electronic device consisting of two optical channels (one for measuring the object's radiation, the second for measuring the background radiation), each of which contains an input mirror, a lens, a set of field diaphragms, a collective, a sector modulator, by means of which sequential overlapping of the measured light fluxes is provided in order to form a signal of their difference, a reference voltage generator for generating an electric signal with a modulation frequency, an optical mixture light fluxes, neutral filters to limit the light fluxes under study, spectral filters to provide measurements in different spectral ranges, a radiation receiver, a two-channel amplifier, one of the channels of which contains an analog selective filter, a synchronous detector and serves to process a signal proportional to luminance, the second one, which contains a selective filter and a synchronous detector, is designed to process a signal proportional to the difference of the frequencies, the logical arrangement CTBA for calculating the contrast of the recording apparatus, the reference radiation source to eliminate the effects of instability priemousilitelnogo tract on the measurement results. A two-channel amplifier between the synchronous detectors and the logic device introduces an adder of electrical signals in which the signals of the first and second channels of the two-channel amplifier are added, thereby eliminating the systematic error of contrast measurement and thereby increasing the accuracy of contrast measurement. 3 il.

Description

a selective filter 15, an analog key 16, a second selective filter 17, synchronous detectors 18 and 19, an adder 20 of electrical signals, a logic device 21 for calculating the contrast, a registering device 22. In front of the modulator 10 there is a source 23 of the reference radiation and a condenser 24, behind the module by torch — mirrors 25 and 26, which direct the radiation of the reference radiation source at the receiving 14. The reference voltage generator controls the operation of the switch 16 and the synchronous detectors 18 and 19.

The telephotometer works as follows.

The radiations from the object and the background with the help of mirrors 1 and 2 are directed into the lenses 3 and 4. Field diaphragms 5 and 6 limit the field of view of the optical channels of the instrument. Groups 7 and 8 will scoop them about the pupils of the lenses in a flat modulator sector 10. After the mo / lm torus, the light fluxes are reduced to o, 1, n with noMOiiibio mixer 11. The total flow after the mixer, carrying information about the brightness of the object and the background and their differences are passed through the neutral and spectral filters 12 and 13 and fed to the photocathode of receiver 14. The electrical signal from the output of the receiver is divided into two: one is fed to the input of the selective filter 15 and further to the synchronous detector 19, the second through an analog switch 16, intended for gating signal to the input of the selective filter 17 and further to the synchronous detector 18. The output of the synchronous detector 19 is removed signal proportional to the difference in luminance from the output of the synchronous detector 18 - proportional greater luminance.

In order to eliminate the ambiguity of the luminance measurement, the outputs of the synchronous detectors 18 and 19 are connected to the outputs of the synchronous detectors, which allows to sum the output signals of the synchronous detectors. The output signal from the adder 20 and the output signal of the synchronous detector 19 are fed to a logic device 21, which is used to calculate the contrast using the formula

-f.

where db is the difference of the rkosts;

Th | - great brightness.

Signals, proportional to luminance, difference of contrast and contrast, are recorded on recorder 22.

The total light flux on the photocathode of the radiation receiver 14 can be represented as:

F B1S1 + B2S2 BiSo- (Bi-B2) S2

BiS0-KB, S2 ..., (1)

0

where FЈ is the total luminous flux at the photocathode of the radiation receiver; So is the area of the light spot projected onto the photocathode; 5 S - part of the area of the light spot

luminance Cg, $ 2 - part of the area of the light spot

brightness BZ, K - contrast.

To reduce the fluctuating noise of the radiation receiver, narrowband selective filters 15 and 17 are used, highlighting the first harmonics of the signals. The amplitude of the first harmonic signal at the output of the filter 17, taking into account the analog H key 16, can be represented as

# 2f0 i

AxcoЈ-Fz cos, (BiSo-KBtS2) X XhosFLF ... (2)

where f is the angle of rotation of the modulator;

Pitch angle corresponding to the modulator slot size 0

(Fig. 3)

S2 (cc) -p- (a - sina) 5 or through the angle of rotation of the modulator

p, iV

52 (f) 5 (f) 2- (2agsoz (so5f-ctgTJr-X

f Xzshf) - 5t (2agssoz (co8f-ctg- -sir)),

0 where 5 (f) 52 (a) 52 (f) 52;

2d is the diameter of the light sheet. Replace the variables, the expression (2) can be represented as

S / 2 ffa

.Socos dx- S (x) X

Xcos-jspd ...,

(3)

Where

phage

GH6 (0,)

whose (oh, fo)

When the contrast between brightness is changed, for example, due to the change in brightness Vd (Bi const), the second integral in expression (3) will change, which will lead to ambiguity in measuring the constant value of brightness V | with systematic error

$ - / g

BICUCT - BIH ™ MS (; t) -cos Vs .. ™

& dx

but

 1ISG

Cos

jr

dx

(four)

where pcio is the systematic bias luminance measurement error;

V | isg - the true value of brightness

In | measured value of brightness B.

To eliminate systematic errors, an adder 20 of electrical signals is inputted into the electrical circuit of the proposed device, to one input of which a signal is output from the output of the synchronous detector 18, defined by the expression (3), and to the second - a signal from the output of the synchronous detector 19, proportional to the difference of power and equal to second integral of expression (3), i.e.

U (fo

(Uvih | 9oo 5 / gB1 S (x) -cosi-jЈ-dx ....

(five)

Jf

L „

The output of the adder is

f / 2

Ueax20CO - B So COS-gpdX.

The logic device receives signals from the outputs of the synchronous detector 19 and the adder 20.

The gain in accuracy due to the exclusion of the systematic error of the rcist in the proposed telephotometer increases as the contrast increases and when / (1 reaches 25% compared to the prototype.

Claims (1)

Invention Formula Telephotometer containing two input mirrors, two lenses, two sets of field diaphragms located in the foci of the lenses, two teams, a modulator, an optical ten 15 optical light flux mixer, neutral and spectral optical filters, a reference radiation source optically coupled to a radiation receiver equipped with an amplifier and connected to the input of an analog switch, a logical and recording device, characterized in that in order to improve the accuracy of contrast measurement , two selective filters, two synchronous detectors, a reference voltage generator and an adder were introduced into it, and the output of the radiation receiver through the successively connected first selective filter Tr and the first synchronous detector is connected to the first inputs of the adder, logic and recording devices, the output of the analog key is through a second selective filter connected in series and the second synchronous detector is connected to the second input of the adder, the output of which is connected to the second 20 inputs of the logic and recording devices, and the control the inputs of the analog key and synchronous detectors are connected to the output of the reference voltage generator, and the output of the logic device is connected to the third input of the register device BUT ..4k.-H / eleven 23 2 I x S