CA2067248C - Multi-wavelength pyrometer - Google Patents
Multi-wavelength pyrometer Download PDFInfo
- Publication number
- CA2067248C CA2067248C CA002067248A CA2067248A CA2067248C CA 2067248 C CA2067248 C CA 2067248C CA 002067248 A CA002067248 A CA 002067248A CA 2067248 A CA2067248 A CA 2067248A CA 2067248 C CA2067248 C CA 2067248C
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- Canada
- Prior art keywords
- temperature
- emission rate
- pyrometer
- computed
- lambda
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000005855 radiation Effects 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims description 8
- 230000006870 function Effects 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims 1
- 238000011156 evaluation Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000003455 independent Effects 0.000 description 1
- 238000006557 surface reaction Methods 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature
- G01J5/602—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature using selective, monochromatic or bandpass filtering
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J2005/0077—Imaging
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Radiation Pyrometers (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Luminescent Compositions (AREA)
- Measuring And Recording Apparatus For Diagnosis (AREA)
- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
- Apparatus For Radiation Diagnosis (AREA)
Abstract
The invention relates to a multiwavelengths pyrometer for measuring the temperature and emission rate of a surface above 900 K. This pyrometer contains several radiation detectors which are sensitive to different wavelengths .lambda.l....lambda.i....lambda.n and a data processor which receives the output signals of the radiation detectors after digitalization, and deduces therefrom, by means of the Wien-Planck law, the temperature, assuming that the surface is an ideal black body. Then, the emission rate is computed from these temperature values according to an approximation law as a function of temperature and the wavelength, and from this the desired temperature is computed. According to the invention, the differences between the pyrometer signals and the pyrometer signals to be expected due to the assumed emission rate and the desired temperature deduced therefrom are computed for several of the approximation laws and the different wavelengths and then that approximation law is selected which represents for all wavelengths the lowest sum of the squares of these differences and the highest precision of temperature and emission rate.
Description
A MULTIWAVELENGTI~S PYROMETER
The invention relates to a multiwavelengths pyrometer for measuring the temperature and emission rate of a surface above 900 K comprising several radiation detectors which are sensitive to different wavelengths ~.1...~.i...~,n and a data processor which receives the output signals of the radiation detectors after digitalization, and deduces therefrom, by means of the Wien-Planck law, the temperature, assuming that the surface is an ideal black body, the emission rate being then computed from these temperature values according to an approximation law as a function of temperature and the wavelength, the desired temperature being deduced therefrom.
From the journal "Temperature", vol. 5, 1982, pages 439 to 446, a rapid pyrometer of the type mentioned above is known. An optical system is directed onto the surface to be measured, which system splits up into six channels by means of a glass fiber bundle, and is led to the photodiodes via narrow band filters. The detector signals are then digitalized and evaluated in a processor.
The evaluation is based on the Wien-Planck equation for black bodies L = C1.~. 5[exp(C2/~,T)-1)] 1 (1) where L is the beam density at the wavelength ~., C1 and C2 are constant terms and T is the temperature of the black body., Since the surface to be examined is normally no ideal black body, the emission rate E must be taken into account, which represents the ratio between the beam density of the black body and the real body.
This emission rate is a function of temperature and wavelength and can be expressed by a Taylor series of the following kind:
In E = a0 + a17~ + a27~2 + . . . ( 2 ) According to experience, the dependance on wavelength in limited wavelength ranges is a steady function, so that the series (2) can be cut off after a few terms.
In the cited article, it is thus proposed to choose a linear approximation of the function (2) and to evaluate res-pectively pairs of wavelengths out of the six measured values of the beam density according to the six wavelengths of the pyrometer and then to find out the temperature by the analysis of the squares of the deviations of the different results.
It has been found out that in difficult cases this method leads to results which do not permit a reliable state-ment as to their precision.
Thus, pyrometrical measurements of highly reflective surfaces, where the emission rate is very low and very un-stable due to possible surface reactions (for example aluminum during metallurgical treatments), are reputed to be difficult.
It is thus the aim of the invention to improve a mul-tiwavelengths pyrometer of the kind cited above in such a way that the computation complexity and the residual error are diminished and that usable results can be obtained even under very unfavorable measurement conditions.
According to the invention, this aim is attained by the fact that the differences between the pyrometer signals and the pyrometer signals to be expected due to the assumed emission rate and the desired temperature deduced therefrom are computed for several of the approximation laws and the different wavelengths, and that then that approximation law is selected which represents for all the wavelengths the lowest sum of the squares of these differences and the highest preci-sion of temperature and emission rate.
Preferably, the processor contains a memory in which a data bank is established for the emission rate of certain materials as a function of temperature and wavelength, the processor also using this data bank for computing the tempera-ture when the same materials are subjected to a pyrometer measurement.
20~'~2~~
The invention relates to a multiwavelengths pyrometer for measuring the temperature and emission rate of a surface above 900 K comprising several radiation detectors which are sensitive to different wavelengths ~.1...~.i...~,n and a data processor which receives the output signals of the radiation detectors after digitalization, and deduces therefrom, by means of the Wien-Planck law, the temperature, assuming that the surface is an ideal black body, the emission rate being then computed from these temperature values according to an approximation law as a function of temperature and the wavelength, the desired temperature being deduced therefrom.
From the journal "Temperature", vol. 5, 1982, pages 439 to 446, a rapid pyrometer of the type mentioned above is known. An optical system is directed onto the surface to be measured, which system splits up into six channels by means of a glass fiber bundle, and is led to the photodiodes via narrow band filters. The detector signals are then digitalized and evaluated in a processor.
The evaluation is based on the Wien-Planck equation for black bodies L = C1.~. 5[exp(C2/~,T)-1)] 1 (1) where L is the beam density at the wavelength ~., C1 and C2 are constant terms and T is the temperature of the black body., Since the surface to be examined is normally no ideal black body, the emission rate E must be taken into account, which represents the ratio between the beam density of the black body and the real body.
This emission rate is a function of temperature and wavelength and can be expressed by a Taylor series of the following kind:
In E = a0 + a17~ + a27~2 + . . . ( 2 ) According to experience, the dependance on wavelength in limited wavelength ranges is a steady function, so that the series (2) can be cut off after a few terms.
In the cited article, it is thus proposed to choose a linear approximation of the function (2) and to evaluate res-pectively pairs of wavelengths out of the six measured values of the beam density according to the six wavelengths of the pyrometer and then to find out the temperature by the analysis of the squares of the deviations of the different results.
It has been found out that in difficult cases this method leads to results which do not permit a reliable state-ment as to their precision.
Thus, pyrometrical measurements of highly reflective surfaces, where the emission rate is very low and very un-stable due to possible surface reactions (for example aluminum during metallurgical treatments), are reputed to be difficult.
It is thus the aim of the invention to improve a mul-tiwavelengths pyrometer of the kind cited above in such a way that the computation complexity and the residual error are diminished and that usable results can be obtained even under very unfavorable measurement conditions.
According to the invention, this aim is attained by the fact that the differences between the pyrometer signals and the pyrometer signals to be expected due to the assumed emission rate and the desired temperature deduced therefrom are computed for several of the approximation laws and the different wavelengths, and that then that approximation law is selected which represents for all the wavelengths the lowest sum of the squares of these differences and the highest preci-sion of temperature and emission rate.
Preferably, the processor contains a memory in which a data bank is established for the emission rate of certain materials as a function of temperature and wavelength, the processor also using this data bank for computing the tempera-ture when the same materials are subjected to a pyrometer measurement.
20~'~2~~
The invention will now be described more in detail with reference to two figures.
Figure 1 shows a flow diagram for the operations to be carried out by the processor.
Figure 2 shows schematically a pyrometer according to the invention.
A six wavelengths pyrometer 1, as it is described in the above-mentioned essay in "Temperature", delivers simul-taneously six radiation intensity values of a body, or its surface respectively, observed by the pyrometer, the wave-lengths used in practice lying between 400 and 2000 nm. The bandwidth of a measurement channel lies under 100 nm.
The measurement values which are proportional to in-tensity are obtained in a known way in photodiodes and then applied to a processor 2 in digitalized form. The latter firstly finds out whether the signals are sufficiently stable, i.e. whether the noise level is sufficiently low. Only if this is the case, the temperature can be computed with a suffi-ciently small error (signal standard deviation: So). Then the law for the determination of the emission rate E is chosen according to equation 2. It must be differentiated between a model of zero order, in which In E is a constant a, indepen-dent of the wavelength, a model of first order, in which In E
linearily depends on the wavelength (the law is defined by the determination of a0 and al) and models of higher order, in which further members of the Taylor series must be evaluated.
First, a model of first order is taken as basis and a0 and al and thus the emission rate for the six wavelengths are determined, a0 and al having the same value in all six deter-mination equations. Basically, the evaluation consists in a sub-routine which minimizes the sum of the squares of the deviations between the measured signals and the beam density value computed by means of the emission value defined by a0 and al, and which evaluates the resulting standard deviation SK of the fitting procedure.
20~~~~~
Figure 1 shows a flow diagram for the operations to be carried out by the processor.
Figure 2 shows schematically a pyrometer according to the invention.
A six wavelengths pyrometer 1, as it is described in the above-mentioned essay in "Temperature", delivers simul-taneously six radiation intensity values of a body, or its surface respectively, observed by the pyrometer, the wave-lengths used in practice lying between 400 and 2000 nm. The bandwidth of a measurement channel lies under 100 nm.
The measurement values which are proportional to in-tensity are obtained in a known way in photodiodes and then applied to a processor 2 in digitalized form. The latter firstly finds out whether the signals are sufficiently stable, i.e. whether the noise level is sufficiently low. Only if this is the case, the temperature can be computed with a suffi-ciently small error (signal standard deviation: So). Then the law for the determination of the emission rate E is chosen according to equation 2. It must be differentiated between a model of zero order, in which In E is a constant a, indepen-dent of the wavelength, a model of first order, in which In E
linearily depends on the wavelength (the law is defined by the determination of a0 and al) and models of higher order, in which further members of the Taylor series must be evaluated.
First, a model of first order is taken as basis and a0 and al and thus the emission rate for the six wavelengths are determined, a0 and al having the same value in all six deter-mination equations. Basically, the evaluation consists in a sub-routine which minimizes the sum of the squares of the deviations between the measured signals and the beam density value computed by means of the emission value defined by a0 and al, and which evaluates the resulting standard deviation SK of the fitting procedure.
20~~~~~
The expected temperature and emission rate errors are computed as the differentials which are obtained by successive incrementation of the signals at the respective error and by repeated computation of temperature and emission rate. It is recommended to control whether a model of zero order would also be applicable, since i-t offers a smaller absolute error in the temperature detection. This is the case when the con-stant al from equation 2 lies below a given value, i.e. when the emission rate practically does not depend on the wave-length. In this case, six independent temperature measurements are obtained for the different wavelengths.
The choice of models of higher order leads to a reduction of the standard deviation SK, but not forcibly of the temperature error. On the contrary, when SK reaches the value of S~, any following increase of the model order (over-fitting) results mostly not in a lesser, but in a higher im-precision of the temperature. When during error evaluation it is found out that the error increases, the optimal model has been found and the constants al, a2,...a~ have been deter-mined.
If the error analysis has shown that the error is especially small, then it is recommended to memorize for later utilization the group of curves connecting the wavelength and the emission rate. Thus, a data bank organized according to the kind of materials of the surface to be examined is estab-lished which can be made use of lateron. This is especially valuable when during a later measurement there are very unfa-vorable measuring conditions, for example colour differen-tiated vapour development in the optical path of the pyrometer or instabilities in the electronics due to high environmental temperature. In this case, the pyrometer measurement values are simply compared to groups of curves evaluated at earlier -times and the temperature can be directly computed therefrom.
Such a data bank fed by the least disturbed signals is shown in Figure 2 with the reference 3. Also other unicolored pyro-meters can be operated with the data of this data bank in parallel.
With the pyrometer according to the invention, the desired evaluations can be carried out during a millisecond even under unfavorable conditions, so that on a screen 4 tem-porary evolution of the temperature or the emission rate can be shown practically in real time also for rapidly developing processes, such as for example the pulse heating by means of a laser. This opens new possibilities for the analysis of rapid-ly developing processes in the temperature range above 700 K
and up to 10.000 K.
The choice of models of higher order leads to a reduction of the standard deviation SK, but not forcibly of the temperature error. On the contrary, when SK reaches the value of S~, any following increase of the model order (over-fitting) results mostly not in a lesser, but in a higher im-precision of the temperature. When during error evaluation it is found out that the error increases, the optimal model has been found and the constants al, a2,...a~ have been deter-mined.
If the error analysis has shown that the error is especially small, then it is recommended to memorize for later utilization the group of curves connecting the wavelength and the emission rate. Thus, a data bank organized according to the kind of materials of the surface to be examined is estab-lished which can be made use of lateron. This is especially valuable when during a later measurement there are very unfa-vorable measuring conditions, for example colour differen-tiated vapour development in the optical path of the pyrometer or instabilities in the electronics due to high environmental temperature. In this case, the pyrometer measurement values are simply compared to groups of curves evaluated at earlier -times and the temperature can be directly computed therefrom.
Such a data bank fed by the least disturbed signals is shown in Figure 2 with the reference 3. Also other unicolored pyro-meters can be operated with the data of this data bank in parallel.
With the pyrometer according to the invention, the desired evaluations can be carried out during a millisecond even under unfavorable conditions, so that on a screen 4 tem-porary evolution of the temperature or the emission rate can be shown practically in real time also for rapidly developing processes, such as for example the pulse heating by means of a laser. This opens new possibilities for the analysis of rapid-ly developing processes in the temperature range above 700 K
and up to 10.000 K.
Claims (2)
1. A method for measuring temperature and emission rate of a surface above 900 K by means of a pyrometer comprising several radiation detectors which are sensitive to different wavelengths .lambda.l... .lambda.i... .lambda.n and a data processor which receives output signals of the radiation detectors after A-D conversion, and deduces therefrom, by means of Wien-Planck law, temperature values, assuming that the surface is an ideal black body, the emission rate being then computed from these temperature values according to a selected one of different approximation laws as a function of said temperature values at the corresponding wavelengths and from this said temperature is computed, characterized in that differences between said output signals and output signals to be expected due to an assumed emission rate and the temperature value deduced therefrom are computed for several of the approximation laws and the different wavelengths, and that then that an approximation law is selected which represents for all the wavelengths the lowest sum of the squares of these differences and the highest precision of temperature and emission rate.
2. A method according to claim 1, characterized in that the data processor contains a memory in which a data bank is established for the emission rate of certain materials as a function of temperature and wavelength, the data processor using this data bank for computing the temperature when the same materials are subjected to a pyrometer measurement.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU87595 | 1989-09-25 | ||
| LU87595A LU87595A1 (en) | 1989-09-25 | 1989-09-25 | MULTI-WAVELENGTH PYROMETER |
| PCT/EP1990/001614 WO1991004472A1 (en) | 1989-09-25 | 1990-09-24 | Multi-wavelength pyrometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2067248A1 CA2067248A1 (en) | 1991-03-26 |
| CA2067248C true CA2067248C (en) | 2000-06-13 |
Family
ID=19731186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002067248A Expired - Fee Related CA2067248C (en) | 1989-09-25 | 1990-09-24 | Multi-wavelength pyrometer |
Country Status (13)
| Country | Link |
|---|---|
| EP (1) | EP0420108B1 (en) |
| JP (1) | JPH06500387A (en) |
| AT (1) | ATE107021T1 (en) |
| AU (1) | AU639029B2 (en) |
| CA (1) | CA2067248C (en) |
| DE (1) | DE59006014D1 (en) |
| DK (1) | DK0420108T3 (en) |
| ES (1) | ES2056328T3 (en) |
| IE (1) | IE64270B1 (en) |
| LU (1) | LU87595A1 (en) |
| PT (1) | PT95405B (en) |
| RU (1) | RU2083961C1 (en) |
| WO (1) | WO1991004472A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1993018494A1 (en) * | 1992-03-11 | 1993-09-16 | The Boeing Company | Thermal condition sensor system for monitoring equipment operation |
| LU88215A1 (en) * | 1993-01-25 | 1994-09-09 | Communaute Europ Del En Atomiq | Device for generating a plurality of secondary light beams from a primary light beam |
| GB9411153D0 (en) * | 1994-06-03 | 1994-07-27 | Land Infrared Ltd | Temperature monitoring |
| IL117951A (en) * | 1995-09-06 | 1999-09-22 | 3T True Temperature Technologi | Method and apparatus for true temperature determination |
| DE19721475A1 (en) * | 1997-05-23 | 1998-11-26 | Eko Stahl Gmbh | Process for non-contact temperature measurement |
| IL122258A (en) * | 1997-11-20 | 2002-08-14 | Israel Aircraft Ind Ltd | Method and system for determining temperature and/or emissivity function of objects by remote sensing |
| EA001536B1 (en) * | 1998-12-04 | 2001-04-23 | Юрий Карлович Лингарт | Method for determining an actual temperature of a real body |
| DE102005018124B4 (en) * | 2005-04-20 | 2007-06-28 | Barke, Woldemar, Dipl.-Phys. Ing. | Method and device for non-contact simultaneous determination of temperature and emissivity of a test object |
| RU2419914C2 (en) | 2006-03-29 | 2011-05-27 | Конинклейке Филипс Электроникс Н.В. | Dual-colour pyrometric measurement of x-ray focal spot temperature |
| US8654924B2 (en) | 2008-11-25 | 2014-02-18 | Koninklijke Philips N.V. | X-ray tube with target temperature sensor |
| RU2468360C1 (en) * | 2011-07-27 | 2012-11-27 | Государственное образовательное учреждение высшего профессионального образования Томский государственный университет (ТГУ) | Method to measure integral coefficient of heat-shielding materials surface radiation |
| US10564041B2 (en) * | 2016-02-04 | 2020-02-18 | Worcester Polytechnic Institute | Multi-band heat flux gauge |
| RU2646426C1 (en) * | 2017-01-11 | 2018-03-05 | Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" (Госкорпорация "Росатом") | Method of the aircraft heated surface temperature determining under the supersonic flow by approach flow |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2572523B1 (en) * | 1984-10-25 | 1987-06-12 | Bertin & Cie | PYROMETRIC METHOD AND DEVICE FOR REMOTELY DETERMINING, OPTICALLY, THE TEMPERATURE AND / OR EMISSIVITY OF ANY BODY OR MEDIUM |
| DD253741A3 (en) * | 1985-07-30 | 1988-02-03 | Univ Dresden Tech | METHOD FOR TOUCHLESS TEMPERATURE MEASUREMENT WITH A MULTI-CHANNEL PYROMETER |
| DD254114A3 (en) * | 1985-07-30 | 1988-02-17 | Univ Dresden Tech | PYROMETRIC MEASURING PROCEDURE |
-
1989
- 1989-09-25 LU LU87595A patent/LU87595A1/en unknown
-
1990
- 1990-09-24 WO PCT/EP1990/001614 patent/WO1991004472A1/en active Application Filing
- 1990-09-24 DK DK90118315.2T patent/DK0420108T3/en active
- 1990-09-24 DE DE59006014T patent/DE59006014D1/en not_active Expired - Fee Related
- 1990-09-24 PT PT95405A patent/PT95405B/en not_active IP Right Cessation
- 1990-09-24 EP EP90118315A patent/EP0420108B1/en not_active Expired - Lifetime
- 1990-09-24 CA CA002067248A patent/CA2067248C/en not_active Expired - Fee Related
- 1990-09-24 AU AU64185/90A patent/AU639029B2/en not_active Ceased
- 1990-09-24 RU SU5011864/25A patent/RU2083961C1/en not_active IP Right Cessation
- 1990-09-24 AT AT90118315T patent/ATE107021T1/en not_active IP Right Cessation
- 1990-09-24 IE IE343690A patent/IE64270B1/en not_active IP Right Cessation
- 1990-09-24 ES ES90118315T patent/ES2056328T3/en not_active Expired - Lifetime
- 1990-09-24 JP JP2513266A patent/JPH06500387A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0420108A1 (en) | 1991-04-03 |
| RU2083961C1 (en) | 1997-07-10 |
| DK0420108T3 (en) | 1994-08-29 |
| IE903436A1 (en) | 1991-04-10 |
| ATE107021T1 (en) | 1994-06-15 |
| AU639029B2 (en) | 1993-07-15 |
| CA2067248A1 (en) | 1991-03-26 |
| EP0420108B1 (en) | 1994-06-08 |
| WO1991004472A1 (en) | 1991-04-04 |
| PT95405B (en) | 1998-06-30 |
| LU87595A1 (en) | 1991-05-07 |
| AU6418590A (en) | 1991-04-18 |
| ES2056328T3 (en) | 1994-10-01 |
| JPH06500387A (en) | 1994-01-13 |
| DE59006014D1 (en) | 1994-07-14 |
| IE64270B1 (en) | 1995-07-26 |
| PT95405A (en) | 1992-05-29 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |