SU1293584A1 - Method of calibrating nephelometer-type optical devices - Google Patents

Abstract

The invention relates to analytical instrumentation and can be used in calibrating nephelometers and other instruments of the same type. The purpose of the invention is to enhance. calibration accuracy. A part of the main (probe) radiation is passed through the analysis zone for the second time, and in this zone there can also be dust particles that give a measuring signal. Received. Sum light is attenuated (10-10 times), exactly matches the pre-set calibration value, and directed to the photodetector. In the method of realizing the Gs also synchronous signal detection. The calibration according to the invention can be carried out without dismantling the instrument and blocking the air flow through the analysis zone. 1 il. with S (L s: 00 NU

Description

The invention relates to analytical instrumentation and can be used to calibrate nephelometric type optical devices (devices) for the chemical, food, construction, mining, and other industries.

The purpose of the invention is to improve the accuracy of calibration.

The drawing shows a diagram of the device that implements the proposed method.

The device comprises an emitter 1, a photodetector 2, a filter unit 3, a probing radiation trap 4, a damper 5, a light guide 6, a light-absorbing element 7 (for example, an optical wedge), a photodetector trap 8. The drawing also shows the analysis zone 9.

The method is implemented as follows.

The emitter 1 generates (e.g., an electromechanical modulator) rectangular light pulses, some of which are received by the photodetector 2 in the measurement mode. In this case, filters 3 are missing (removed from the measuring circuit), and damper 5 is inserted.

In the calibration mode, the instrument installs a filter unit 3. At the same time, the modulated light flux, falling into the trap 4 when the damper 5 is open in the calibration mode, is transmitted through the light guide 6 through the element 7 to the trap of the photodetector 8, the optical system of which forms the image of the fiber end zone 9 analysis. The optical system of the photodetector 8 transfers the image of the end of the fiber to the photosensitive area of the photodetector 2.

The brightness of the fiber spot is 10 -10 times the brightness of the dust volume for a background concentration of 20-30 mg / m, under which the instrument is calibrated.

Thus, the sum of the reference signal and the measuring signal from dust, which is 10-10 times weaker than the reference signal, is fed to the photodetector.

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go With this ratio of signals, the additive component, which is the radiation scattered in the dust, is suppressed by the filters 3 to values that are beyond the sensitivity threshold of the photodetector.

Element 7 can be implemented by a polarizer-analyzer pair or by an optical wedge. It changes the flow in the range from 30 to 70% and serves to accurately secondary the attenuation of the sum signal to a predetermined level.

The proposed: method allows for the presence of dust in the analysis zone during the calibration process, which allows this operation to be carried out without dismantling the instrument and blocking the air flow through the analysis zone. The modulation operations followed by 1 {m synchronous detection can further improve the calibration accuracy.

Claims (1)

Invention Formula A method of calibrating optical devices of the nephelometric type, which direct the probe radiation into the analysis zone, form a reference signal using a portion of the radiation that has passed the analysis zone, record the recording signal and calibrate the device according to its size in order to increase calibration accuracy, pre-modulate probe radiation, form a reference signal from radiation pulses that exceed measuring pulses by 10–10 times in amplitude, sum up the reference pulses and measure These pulses attenuate the total pulses to a value commensurate with the magnitude of the measuring pulses, while suppressing the additive component of the signal to a value beyond the sensitivity threshold of the device, secondarily attenuate the total pulses to a predetermined value, and during registration, the received pulses are synchronously detected . Editor E. Kopcha Compiled by V.Kalechits Tehred M. Khodanich Proofreader O. Lugov Order 377/46 Circulation 777 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4