SU1689766A1 - Meter of radiation fluxes - Google Patents

Abstract

The invention relates to a technique for measuring radiant energy and can be used in optical gas analyzers, radiometers, spectrometers, etc. The aim of the invention is to improve the measurement accuracy. The device contains an optical system equipped with a modulator, successively connected a radiation receiver and a phase-sensitive amplifier, as well as a serially connected clock generator, optically coupled to the modulator, a frequency divider into two and a driver of control signals, the output of which is connected to the control input phase-sensitive amplifier. The frequency of interruption of the light flux in the sync pulse generator is twice as high as the modulation frequency of the measured radiation fluxes in the optical system. 1 il.

Description

The invention relates to a technique for measuring radiant energy and can be used in optical gas analyzers, radiometers, spectrometers, etc.

The purpose of the invention is to improve the measurement accuracy by improving the stability of the meter in conditions with varying ambient temperatures.

The drawing shows a structural diagram of a radiation flux meter.

The radiation flux meter contains an optical system 1, a modulator 2, a radiation receiver 3 connected in series, a phase-sensitive amplifier 4, as well as a series-connected driver of synchro pulses 5, optically connected to the modulator 2, frequency divider 6, and driver 7 of the control

signals whose output is connected to the control input of the phase-sensitive amplifier 4.

The meter works as follows.

The radiation supplied from the optical system 1 to the radiation receiver 3 is modulated by the modulator 2 at a predetermined frequency. Using the same modulator, but with a double frequency, the light beam is modulated in an optocoupler of a synchro generator 5, which ensures its optical coupling by the modulator.

The output signal of the radiation receiver 3 is fed to the input of the phase-sensitive amplifier 4, in which it is amplified, filtered, synchronized, and, if necessary, normalized or subjected to

ABOUT

with y

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additional processing and logging.

The operation of the fz-sensitive amplifier is controlled synchronously with the modulation frequency of the radiant fluxes supplied by the non-photodetector. Dd of this, the frequency of the output electric signal of the generator of the 5 sync pulses before supplying the control signals to the input of the generator 7 is halved with the help of dells of frequency 6, which can be used as a trigger.

Thus, regardless of the duty cycle of the output signal of the generator of 5 sync pulses, which is subject to changes in unstable temperature conditions, the duty cycle of the signal at the output of frequency divider 6 and, accordingly, control signals at the output of generator 7, will remain constant. The required phase shift of the control signals can be maintained by any known method, and the phase shifter required in this case can be located both in the driver 7 of the control signals and in the driver 5 of the clock pulses.

An increase in ambient temperature leads to a decrease in the light gaps relative to the tempo in the sync pulse generator. This results in an interfering additive in the signal being processed, which is subtracted from the useful (informative) signal or summed with it, i.e. causes a change in the output measured signal level.

Suppose that with increasing temperature, the duty ratio of the control signals changed by 0.1% with respect to their initial duty cycle, for example, equal to 2. We also assume that the modulation of radiation fluxes supplied to the photodetector is rectangular; the amplitude of the modulated signal is normalized and equal to one. In this case, an interfering additive occurs, i.e. an interfering variable signal appears with an amplitude equal to

0.1% amplitude modulated signal.

Suppose that we are not interested in the amplitude of the modulated signal, i.e. not

the total level of the modulated radiation flux, and its slight change relative to this general level (for example, in gas analyzers, where the difference between the absorbed and unabsorbed radiation is measured) and assume that this change also amounts to 0.1% of the amplitude of the modulated signal.

Thus, when changing the duty cycle of control pulses, the measured

the signal will be no longer 0.1%, but 0.2% of the amplitude of the modulated signal. If the initial duty cycle is restored, then the measurement accuracy of such a signal will increase accordingly by 2 times. When reducing the level of measurable useful

Signal accuracy of its measurement will increase. The use of the invention makes it possible to increase the measurement accuracy by a factor of 2 or more when the meter is operated in conditions that are unstable in temperature.

Claims (1)

Invention Formula A radiation flux meter containing an optical system equipped with a modulator, the output of which is optically coupled to the radiation receiver, the output of the radiation receiver is connected to the input of a phase-sensitive amplifier, a sync pulse generator, with a light beam of which the modulator signals, the output of which is connected to the control input of a phase-sensitive amplifier, characterized in that, in order to improve the measurement accuracy, a frequency divider is inserted in it, which is connected between the output of the sync pulse generator and the input of the control signal generator, and the modulator is configured to interrupt the light beam of the sync pulse generator at the doubled frequency relative to the modulation frequency of the measured radiation fluxes in the optical system.