DE2363431A1 - METHOD AND DEVICE FOR DETERMINING RADIATION ABSORPTION - Google Patents

Description

Method and device for
Determination of radiation absorption.

The invention relates to a method and a device for determining the radiation absorption in a gaseous or
liquid medium. This can be different radiations, for example electromagnetic radiation or
Ultrasonic radiation or radioactive (isotope) radiation.

The measurement of the absorption of the particular type of radiation in question in various media, including radiation
in the range of ultraviolet, visible and infrared light

409826/1109

Andrejewski, Honke & Gesthuysen, patent attorneys, 4300 Essen 1, Theaterpfatx

generally takes place in such a way that the medium in which the measurement is to be carried out in.dispersive measuring Spectrophotometers or in non-dispersive photometers in a cuvette is brought into a parallel beam path, the change in light intensity compared to the same arrangement without this medium being measured. Specific Difficulties arise in performing the two measurements when it comes to the influence of the measuring device switch off or to keep the influence constant. For this Purpose, for example, a comparison beam is deflected by a second identically designed optical system or a Comparison wavelength used at which the to be examined Substance is less absorbed, or the contents of the cuvette are also replaced or the transmitter and receiver properties are checked to stabilize.

The disadvantage of two-beam photometers with a separate beam path is the risk of different changes in the optical properties on the two beam paths. Also, if two beams of different wavelengths are used, the comparison beam can be influenced in a different way than the measuring beam, namely as a result of changes in the medium to be examined or as a result of any filters used despite almost the same optical path, ... whereby the -Measurement results can be inaccurate. In addition, there is the difficulty of finding a comparison wavelength that is suitable for the respective measurement problem. In the case of single-beam photometers, the uncertainty in the determination of the intensity of the reference radiation must on the one hand by special stabilization of the. ^;

409826/1109

Andrejewski, Honke & Gesthuysen, patent attorneys, 4300 Essen!, Theaterplatz3

Receiver and transmitter as well as, on the other hand, the cumbersome intermediate rinsing of the cuvette will.

The invention has therefore set itself the task of providing a method and to realize a device by means of which BEZW. by means of which the influence of the optical changes and the instability of the receiver and transmitter properties is eliminated in a photometer.

The method according to the invention and the device according to the invention can be used in practice, for example, wherever there is automatic process control Changes in concentration can be observed through optical devices. In the range of visible radiation These changes can consist, for example, of changes in the dyeing intensity, as in a dye liquor in the, Textile industry, in the production of beverages in the food industry, with completely different products in chemical technology (for example coloring solutions, lacquers, emulsions), also in dimensional analyzes, in precipitation processes and colorometric measurements as well as in the determination of the amount of particles, the determination of the sludge or turbidity content and the color of industrial wastewater in wastewater technology. In the radiation range near infrared radiation, the water determinations in organic liquids are from Importance, while many organic substances are of interest in the ultraviolet radiation range, for example benzene, oil and carbon disulfide as well as chlorine and carbon disulfide gas,

A09826 / 1109

Andrejewsld, Honke & Gesthuysen, patent attorneys, 4300 Essen T, Theaterplatz 3

also the gases sulfur dioxide and nitrogen dioxide, which are of interest in terms of environmental protection.

The method according to the invention for determining the radiation absorption in a gaseous or liquid medium is essentially characterized in that there are two transmitters and two receivers in the medium to be measured in such Positions are arranged that two different radiation abs would arise from each transmitter to each receiver, with the radiation distances from the first transmitter to the first and to the second receiver equal to the radiation distances from the second Transmitter to the second and to the first receiver are, and that individual measurements of the radiation absorption from each transmitter to each receiver, whereby the influence of changes in the transmitter and receiver properties is practically eliminated.

A device according to the invention for carrying out this method is essentially characterized in that they each have two transmitters and receivers in such an arrangement has that the distances from the first transmitter to the first and to the second recipient equal to the corresponding distances of the second transmitter to the second and first receiver.

A more detailed explanation of the invention can be found in FIG following description of a preferred embodiment of a device according to the invention with reference to FIG accompanying drawings; show it:

40 98 26/1109

Andrejewski, Honke & Gesthuysert, patent attorneys, 4300 Essen 1, Theaterplatz

Figures 1 and 2 two schematic sketches to explain the principle of the invention; and

Figure J and 4 respectively a plan view. a cut through

a practical embodiment of the invention.

The idea of the invention should initially be based on FIG. 1 in connection with the determination of the absorption of electromagnetic Radiation will be explained. In the measuring arrangement shown there are two optical transmitters A and B and two optical receivers C and D arranged opposite one another in the corner points of a square. It is essential that every transmitter has two different distances to the two receivers, but they must be the same in pairs.

Fluorescent tubes or any other light sources in the infrared, visible and ultraviolet light can be used as transmitters Area are used, for example light-emitting diodes or gas discharge larapen. It can also use the light from a lamp be guided via mirrors or optical fibers to two outlet openings, which serve as transmitters and alternately Emit light through mechanically or electro-optically operated panels. Suitable radiation-sensitive receivers can be used as receivers Detectors, e.g. photo elements, photo resistors, Photo diodes, photo transistors or photo multipliers can be used. .

40 9 826/1109

Honk © $ k Gesfhuysen, PofenfQiiiwiiSf © ,, 43 @ 9 Essen 1 _f Theoferplofz 3

In order to achieve the greatest possible light output * anyone can Transmitter can be equipped with a reflector to avoid the main radiation to align with the two receivers.

As FIG. 1 shows, the distance from transmitter A to receiver "C" is equal to x, and the distance from transmitter A to receiver D is equal to Xp-, while the distance from transmitter B to receiver C is equal to Xg and the distance from transmitter B to Receiver D is equal to X _1. The radiation should pass through the substance to be measured over the entire path lengths JlC = X ₁ , AD = X ₂ and BD = X _{1. In} the case of gaseous and liquid media, this can be achieved by using a probe is immersed in the medium with the two optical transmitters and the two optical receivers. Depending on the intended use, the radiation of the transmitters can correspond to the radiation emission of the lamps or can be made monochromatic by filters attached directly to the transmitters. The radiation does not need to go through an optical system To be bundled, but to achieve the greatest possible light yield at the receivers, it is advantageous if the turner have a radiation characteristic, in which possible As much light as possible emerges in the direction of the two receivers.

The basis of the determination of absorption is the difference in optical path lengths of each transmitter to the two receivers, in the square arrangement according to Figure 1 so along the sides and the diagonals. The radiation intensity of the transmitter is I, respectively. .Χ -.-. Then the radiation intensities are which the recipients reach, in each case:

0 9 826/1109

Andrejewski, Honke & Gesthuysen, patent attorneys, 4300 Essen 1, Theaterplatz 3

Receiver C from transmitter A respectively. Sender B:

^X CA " ⁶ CA ^K C ^X A ^ex

¹ CB ~ ⁶ GB C ¹ B

Receiver D from transmitter A respectively. Sender B:

^X DA ~ ^S DA ^K D ^X A
DB ^{= S} DB ^k D ¹ B ^{e λ}

FIG. 4 shows a section through the measuring arrangement according to FIG. 3 seen from the right-hand side of FIG. 3, the same reference numerals as in FIG. 3 being used as far as possible. The flowing medium 11 'flows past the immersed transmitters A and B and the receivers C and D, although only the tubular transmitter B and the tubular receiver D can be seen in FIG. The two pipes, which the transmitter respectively. contain the receiver are at the lower end by a plug 13 BEZW. IK closed and the basin is covered at the top by means of a cover 17 with the interposition of a sealing ring 18, the cover being screwed on tightly by screws 15, 16.

In summary it can be stated that the basic concept of the measuring principle is based on the propagation properties of waves when they pass through absorbent media.

0-9826 / 1 109

Andrejewski, Honke & Gesthuysen, patent attorneys, 4300 Essen !, Theaterplatz

8th -

The weakening of the radiation when it is in a medium propagates can be expressed in terms of an absorption factor or an absorption constant. The Eambert Beersche Law states that the absorption is linearly proportional to the concentration of a medium in which an absorption takes place can. In this way it is possible to carry out quantitative chemical determinations very precisely. the Invention largely overcomes the difficulties normally encountered with absorption photometric Measurements arise as a result of the inconsistency of the optical properties and the properties of the transmitters and receivers. the The invention enables the absorption constants to be found in a simple manner with the aid of a versatile measuring probe in a comparatively simple optical training.

Of course, the invention is not limited to the above Embodiment described is limited, but it can be modified depending on the operational needs, so long the measuring principle according to the invention is retained.

409826/1109

Claims (6)

Andrejewski, Honke & Gesthuysen, patent attorneys, 4300 Essen 1, Theaterplatz - 9 patent claims: r IJ method for determining the radiation absorption in one gaseous or liquid medium, characterized in that two transmitters (A, B) and two receivers (C, D) are placed in the medium in such positions that there are two different radiation path lengths from each transmitter to each recipient in such a way that. the radiation . Path length through the medium from the first transmitter (A) to the first receiver (C) is equal to the radiation path length from the second transmitter (B) to the second receiver (D) and the radiation path length from the first transmitter (A) to the second receiver (D) is equal to the radiation path length from the second transmitter (B) to the first receiver (C), and that by individual measurements that of each transmitter to "each." Receiver reaching radiation the influence of changes the transmitter and receiver properties are practically switched off » 2. The method according to claim 1, characterized in that it the radiation is electromagnetic radiation. J5. Method according to claims 1 and 2, characterized in that that optical devices are used as transmitters (A, B) and receivers (C, D). 4. Apparatus for performing the method according to one of the Claims 1-5 * characterized in that they have two transmitters (A, B) and two receivers (C, D) in such an opposite 409826/1109 Andrejewski, Honke & Gesthuysen, Patenfanwäite, 4300 Essen 1, Theaterplatz - 10 - lateral relationship arranged to each other contains that the Distances from the first transmitter (A) to the first receiver (C) and to the second receiver (D) equal the corresponding distances from the second transmitter (B) to the second receiver (D) and to the first receiver (C). 5 · Device according to claim 4, characterized in that the two transmitters (A, B) and the two receivers (C, D) opposite each other "in the corners of a square or one Rectangle or a trapezoid with any distances between the transmitters and the receivers are arranged. 6. Apparatus according to claim 5 * characterized, that the receivers (C, D) are circular and are arranged between the two transmitters (A, B). 7 · Device according to any one of claims 4-6, characterized characterized in that the transmitter (A, B) and the receiver (C, D) are housed in a special housing which is used for Measurement can be immersed in the medium in which the measurement is to be carried out. Patent attorney. 409826/1109