SE413205B

SE413205B - OPTICAL METDON

Info

Publication number: SE413205B
Application number: SE7806189A
Authority: SE
Inventors: T Brogardh
Original assignee: Asea Ab
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1980-04-28
Also published as: SE7806189L

Description

_ »sun-e . eniszzn' *nu 10 15 20 2.51 30 55 .-.-.:r-r.)2;~.:_:......;w:i url-Wu. vaoeïëälz På. bifogade ritningar visar figurerna. 1, 2, 3 och 4 alternativa utföringsformer av ett mätdon enligt uppfinningen. Figurer-na 1a, 2a, 2b, 3a och 4a visar detal- jer i motsvarande huvudfigur; ' I samtliga ritningsfignxrer är den första ljusinledande fibern beteoknad 1, den andra ljusinledande fibern 13 och de två. ljusutledande fibrerna. 2 och 3. En lys- diod, alternativt en halvledarlaser, 4 med ett styrdon 7 'är anordnad att sända ljus in ifibern 1 och intensiteten hos ljuset är styrd av styrdonet. För fibern 13 finns en motsvarande ljuskälla 14 med ett styrdon 15. Det genom de ljusutled- ande fibrerna 2 resp 3 kommande ljusflödet mottages av fotodetektorerna. 5 resp 6, vars fotoströmmar förstärkas i elektronikenhetenza 8 resp 9. _ »Sun-e. eniszzn '* nu 10 15 20 2.51 30 55 .-.- .: r-r.) 2; ~.: _: ......; w: i url-Wu. vaoeïëälz On. attached drawings show the figures. 1, 2, 3 and 4 alternative embodiments of a measuring device according to the invention. Figures 1a, 2a, 2b, 3a and 4a show the details of you in the corresponding main figure; ' In all the drawing figures, the first light-initiating fiber is denoted 1, the second light-initiating fiber 13 and the two. the light-emitting fibers. 2 and 3. A diode, alternatively a semiconductor laser, 4 with a control device 7 'is arranged to transmit light in the fiber 1 and the intensity of the light is controlled by the controller. For the fiber 13 there is a corresponding light source 14 with a control device 15. It through the light emitting the light flux coming from the fibers 2 and 3, respectively, is received by the photodetectors. 5 and 6, respectively whose photo currents are amplified in the electronics units 8 and 9, respectively.

Vid det i figur 1 visade mätdonet faller en del av ljuset från den första ljus- inledande fibsrn 1 genom ett horisontellt, genomskinligt fält 19 mellan tvâ skärm- ande partier 18 hos en skiva 17, som visas i figur 1b och som är placerad mellan sensordelen 20, som uppbär den fria änden av fibern 1 ooh sensordelen 25, som upp- bär fibrerna 2, 3 och 13. Figur 1b visar skivan 17 sedd i ett snitt I-I i figur 1. Sensordelen 20 är anordnad att kunna röra sig enligt pilen 20a i figur 1. När sensordelen 20 rör sig uppåt i förhållande till sensordelen 25, komer mer ljus att kopplas- från fibern 1 in i fibern 3 och mindre ljus från fibern 1 till fibern 2. När sensordelen 20 rör sig nedåt komer omvända förhållanden att råda. Efter- som fibrerna 2, 3 och 13 är fixerade i sensordelen 25 kommer ljuset från fibern 13 att kopplas in i fibrerna 2 och 3 genom reflexion mot de skärmande ytorna 18 på. skivan 17 på. ett sådant sätt, att fördelningen av ljuset från fibern 13 till fibrerna 2 och 3 är oberoende av den relativa rörelsen mellan sensordelarna 20 “h 25- Ljuset i fibern 13, som alstras av ljuskëllan 14, är modulerat av styrdonet 15 med frekvensen fo, som erhålles från en oscillator 16. För kompensering av de in- stabiliteter, 'som kan uppstå. i endera av fibrerna 2 resp 3 med tillhörande detek- tor 5 resp 6 och förstärkarelektronik 8 resp 9, är en reglerbar förstärkare 21, 'alternativt en multiplikator eller reglerbar spänningsdelare, ansluten till elektronikens 9 utgång och styrd från en reglerkrets 27 på. sådant sätt, att i skillnaden mellan amplitudema hos växelströmskomponenterna med frekvensen. fo på. elektronikens 8 resp förstärkarens 21 utgångar hålls lika med noll. Detta åstad- kommas genom att de båda detektorsignalernas fo-komponenter filtreras ut med hjälp av bandpassfilter 28 resp 22, likriktas i likriktare 29 resp 23 och där- a efter lågpassfiltreras i lâgpassfilter 30 resp 24. De så behandlade signalerna a påföras plus- resp minusingângen på. ett summeringsdon 26 och den därifrån er- ' hållna. skillnadssigixalen påföres regler-kretsen 27, som styr förstärkaren 21, så 4211:. L* 's-:w --, 10 15 20 25 50 35 _ .,>........1...--..«.1 , V... ,. 1so61s9-éwm att de båda fO-komponenterna från elektronikenheten 8 och förstärkaren 21 får samma amplitud, vilket garanterar riktig matchning av de två fiberoptik- och optoelelctronilcgrenarna från sensorn. För ett uppnå en absolutstabilisering av givarsystemet summeras signalerna från elektronikenheten 8 och förstärkaren 21 i ett summeringsdon 10. Smmasignalen lågpassfiltreras i ett lågpassfilter 51 och påföres ena ingången till ett subtraheringsdon 52, på. vars andra ingång på.- föres en referenssigial Vref. Donets 52 utsignal påföres en reglerkrets 55» 80111 5176611 5311518131 till lysdiodens 4 styrdon 7 och därmed reglerar ljuset från lys- dioden på. sådant sätt, att den filtrerade summasig-rzalen från filtret 51 hållas lika. med referenssigzzalen Vmf. Mätsigzzalen erhålles genom bildandet av skillna- den mellan de matchningsreglerade signalerna från enheterna 8 och 21 i ett subtra- heringsdon 11 och filtrering av skillnadssigrialen :L låpgassfiltret 54. Den filt- rerade signalen påföres ett mätinstrument, som kan vara. av någon i och för sig känd typ.In the measuring device shown in Figure 1, part of the light falls from the first light source. initial fiber 1 through a horizontal, transparent field 19 between two shields portions 18 of a disc 17, which is shown in Figure 1b and which is placed between the sensor part 20, which carries the free end of the fiber 1 ooh the sensor part 25, which supports the carries the fibers 2, 3 and 13. Figure 1b shows the disc 17 seen in a section I-I in figure The sensor part 20 is arranged to be able to move according to the arrow 20a in figure 1. When sensor part 20 moves upwards relative to sensor part 25, more light comes to be coupled from the fiber 1 into the fiber 3 and less light from the fiber 1 to the fiber 2. When the sensor part 20 moves downwards, the reverse conditions will prevail. After- as the fibers 2, 3 and 13 are fixed in the sensor part 25, the light comes from the fiber 13 to be coupled into the fibers 2 and 3 by reflection against the shielding surfaces 18 on. disc 17 on. in such a way that the distribution of the light from the fiber 13 to the fibers 2 and 3 are independent of the relative movement between the sensor parts 20 H 25- The light in the fiber 13, which is generated by the light source 14, is modulated by the control device 15 with the frequency fo obtained from an oscillator 16. To compensate for the stability, 'which may occur. in either of the fibers 2 and 3, respectively, with associated tor 5 and 6 and amplifier electronics 8 and 9, respectively, is an adjustable amplifier 21, 'alternatively a multiplier or adjustable voltage divider, connected to electronics 9 output and controlled from a control circuit 27 on. such that, that in the difference between the amplitudes of the AC components with the frequency. fo on. the outputs of the electronics 8 and the amplifier 21, respectively, are kept equal to zero. This by filtering out the fo components of the two detector signals by means of bandpass filters 28 and 22, respectively, are rectified in rectifiers 29 and 23, respectively, and a after low-pass filters in low-pass filters 30 and 24, respectively. The signals thus processed a the plus or minus steam is applied to. a summing device 26 and the one obtained therefrom 'held. the difference signal is applied to the control circuit 27, which controls the amplifier 21, so 4211 :. L *'s-: w -, 10 15 20 25 50 35 _.,> ........ 1 ...-- .. «. 1, V ...,. 1so61s9-éwm that the two fO components from the electronics unit 8 and the amplifier 21 receive the same amplitude, which guarantees correct matching of the two fiber optics and the optoelectronilg branches from the sensor. For one achieve an absolute stabilization of the sensor system sums the signals from the electronics unit 8 and the amplifier 21 in a summing device 10. The SMS signal is low-pass filtered in a low-pass filter 51 and applied to one input of a subtraction device 52, on. whose second entrance on.- carries a reference signal Vref. The output signal of the device 52 is applied to a control circuit 55 »80111 5176611 5311518131 to the control device 7 of the LED 4 and thus regulates the light from the diode on. in such a way that the filtered sum sigal from the filter 51 is kept equal. with the reference sigzal Vmf. The measurement hall is obtained by the formation of differences between the matching regulated signals from units 8 and 21 in a subtraction filter 11 and filtering the difference signal: L the flue gas filter 54. The filter signal is applied to a measuring instrument, which may be. by someone per se known type.

Figur 1b visar ett annat arrangemang för stsbilisering av mätsignalen till mät~ instrumentet 12. Utsigxxalerna från summsringsdonen 10 resp 11 påföres vie fil- terkretssrna 51 resp 54 en kvotbildare 65, vars utsignal påföres mätinstrumentet 12. Signalen Vref påföres då styrdonet 7 direkt, varigenom reglerkretsen 55 och subtraheringsdonet 52 utgår.Figure 1b shows another arrangement for stabilizing the measurement signal to measurement ~ instrument 12. The output axes from the buzzer rings 10 and 11, respectively, are applied to the circuits 51 and 54, respectively, a ratio generator 65, the output of which is applied to the measuring instrument 12. The signal Vref is then applied directly to the control device 7, whereby the control circuit 55 and subtractor 52 is deleted.

Figur 2 visar det aktuella sensorarrsrxgemanget tillämpat på. en sensor enligt huvudpatentet. Förutom att denna figur visar appliceringen av den andra ljusin- ledande fibern 15 i en annan sensortyp än den som visas i figur 1, visas även en elektronik, som är lämplig för det fall att ljuset i de två. ljusutledande fib- rerna 2 och 5 är 'smplitudmodulerade vid två. olika frekvenser fo och f1. Natur- ligtvis är denna. elektronik liksom elektroniken enligt figurerna. 1 och 5 använd- bar vid sensorvarianter enligt såväl huvudpatentet som tilläggspatentet 7805086.Figure 2 shows the current sensor device applied to. a sensor according to the main patent. In addition to this figure showing the application of the second light input The conductive fiber 15 in a different type of sensor than that shown in Figure 1 is also shown electronics, which is suitable in the case of the light in the two. light-emitting fiber rs 2 and 5 are amplitude modulated at two. different frequencies fo and f1. Nature- of course this is. electronics as well as the electronics according to the figures. 1 and 5 used bar for sensor variants according to both the main patent and the additional patent 7805086.

Figur 2a visar mer detaljerat uppbyggnaden av sensorn med den azxdra ljusinledande fibern 15, från vilken ljus reflekteras mot en skärm 55 och in i de ljusutledande .fibrerna 2 och 5'på. ett sådant sätt, att förhållandet mellan det från fibern 15 till fibern 2 och från fibern 15 till fibern 5 reflekterade ljuset är konstant och oberoende av skärmens 55 läge. En del sv ljuset från den ljusinledsnde fibern 1 reflekteras mot en spegel 56 bakom skärmen 55 in i en spalt 37, som är upptagen i skärmen, och därefter in i de båda ljusutledsnde fibrerna 2 och 5. Skillnaden mel- lan de ljuàflöden, som uppträder i de båda ljusutledsnde fibrerna komer därigenom att bli en funktion av skärmens läge i horisontell led. Matchningsstabiliseringen åstadkommeshär genom' att i ett subtralxeringsdon 59 bildas skillnaden mellan de-s- tektorsigizalezns från kretsarna 8 och 21, varefter skillnadssigrialen passerar ett bandpassfilter 40, likriktes i en likriktsre 41 och efter att ha. passerat ett låg- 10 15 20 25 30 35 .- -. .. ...wave-vn *~ ~-\a :vara ..._.7...ä.ö6,.1..,8_..,9.;2 passfilter 42 påföres en regulator 45 som felsignal, varefter regulatorn styr den styrbara. förstärkaren 21 så, att skillnadssigxalen från donet 39 efter amplitudde- modulering vid frekvensen fo i kretsarna. 40, 41, 42 bâlles lika med noll. 'Absolut- stabiliseringen sker genom att signalerna från donen 8 och 21 summeras i suunme- ringsdonet 44, bandpassfiltreras- i ett filter 45, likriktae i en likriktare 46 och iágpaesfiitrem 1 ett :mer meant pafares ena ingången av ett subti-ahe- ringsdon 438, som bildar skillnaden mellan denna signal och en referenssigizal Vref.Figure 2a shows in more detail the structure of the sensor with the azxdra light initiator the fiber 15, from which light is reflected against a screen 55 and into the light emitting .fibers 2 and 5'on. in such a way that the ratio of that of the fiber 15 to the fiber 2 and from the fiber 15 to the fiber 5 the reflected light is constant and independent of the position of the screen 55. Some sv the light from the light-initiating fiber 1 is reflected against a mirror 56 behind the screen 55 into a gap 37 which is occupied in the screen, and then into the two light-emitting fibers 2 and 5. The difference between the light fluxes which occur in the two light-emitting fibers are thereby to become a function of the horizontal position of the screen. The matching stabilization is achieved here by forming in a subtraction device 59 the difference between the tektorsigizalezns from circuits 8 and 21, after which the difference signal passes one bandpass filter 40, rectified in a rectifier 41 and after. passed a low 10 15 20 25 30 35 .- -. .. ... wave-vn * ~ ~ - \ a: vara ..._. 7 ... ä.ö6, .1 .., 8 _ .., 9.; 2 pass filter 42 is applied to a controller 45 as an error signal, after which the controller controls it controllable. the amplifier 21 so that the difference signal from the device 39 after the amplitude modulation at the frequency fo in the circuits. 40, 41, 42 are equal to zero. 'Absolutely- the stabilization takes place by summing the signals from devices 8 and 21 in ring device 44, is bandpass filtered in a filter 45, rectified in a rectifier 46 and iágpaesfiitrem 1 ett: mer meant pafares one input of a subti-ahe- ring device 438, which forms the difference between this signal and a reference digital Vref.

Den erhållna skillnadssignalen användes som felsignal in till en regulator 49, vars utsignal styr en förstärkare 50, som reglerar amplituden hos utsignalen från en osoillator 51 med frekvensen f, på, ett sådant sätt, att den för frekvensen f1 i donen 45, 46 och 47 demodulerade summasigzmalen hållas lika med referenssigialen Vref. lfâtsigzzalen erhålles slutligen som skillnadssigxalen från donet 39, efter amplituddemodulering vid._ frekvensen f, i kretsarna 53, 54 och 55, till mätdonet 12. Signalen med frekvensen f genereras av en oscillator 52 och matar styrdonet O 15.The obtained difference signal is used as an error signal into a controller 49, whose output signal controls an amplifier 50, which controls the amplitude of the output signal from an osoillator 51 with the frequency f1, in such a way that it for the frequency f1 in the means 45, 46 and 47 demodulated sum sigmals are kept equal to the reference signal Vref. The lfatsigzzal is finally obtained as the difference sigxal from the device 39, after amplitude demodulation at the frequency f, in the circuits 53, 54 and 55, of the measuring device 12. The signal with the frequency f is generated by an oscillator 52 and supplies the controller O 15.

Figur 2b visar en variant av sensorn enligt figur 2a. Genom en något annorlunda. utformning av skärmen 35 i sensorn komer mindre ljus att koma in i de båda ljusutledande fibrerna 2 och 3 då skärmen rör sig åt vänster, medan mer ljus kommer in i fibrerna då. skärmen rör sig åt höger. Detta medför, att summaljuset är en funktion av skärmens läge medan skillnadsljuset är konstant och oberoende av skärmens rörelse i sidled. Spalten 37 i figur 2a komer då att motsvaras av de båda spaltöppningarna 37a och 37b i figur 2b. I elektroniken medför ändringen av spalten att subtraheraren 39 skall vara en summstor och summeringsdonet 44 skall utbytae mot en subtraherere. I övrigt är elektroniken oförändrad.Figure 2b shows a variant of the sensor according to figure 2a. Through a slightly different. design of the screen 35 in the sensor, less light will enter the two light-emitting fibers 2 and 3 as the screen moves to the left, while more light enters the fibers then. the screen moves to the right. This means that the sum light is a function of the position of the screen while the difference light is constant and independent of lateral screen movement. The column 37 in Figure 2a will then correspond to the two gap openings 37a and 37b in Figure 2b. In electronics, the change entails of the column that the subtractor 39 should be a sum size and the summing means 44 shall exchange for a subtractor. Otherwise, the electronics are unchanged.

Figur 3 visar, att man -i stället för att koppla in ljuset från den andra ljusin- ledande fibern 13 till de ljusutledande fibrerna 2 och 3 i själva sensorn, kan man göra. detta utanför sensorn någonstans mellan sensorn och ljusdetektorema. Då. er- hållas emellertid ingen matohningsreglerizzg för den del av det ljusutledande fiber- paret, som befinner sig mellan sensorn och inkopplingsstället. De i sensorn ingå.- ende elementen har beskrivits i anslutning till figur 1 och upprepas därför ej här.Figure 3 shows that instead of switching on the light from the other light input, conductive fiber 13 to the light-emitting fibers 2 and 3 in the sensor itself, one can do. this outside the sensor somewhere between the sensor and the light detectors. Then. your- however, no feeding regulation is maintained for that part of the light-emitting fiber. the pair, which is located between the sensor and the connection point. Those included in the sensor.- The only elements have been described in connection with Figure 1 and are therefore not repeated here.

För att få. in ljus från den andra ljusinledande fibern 13 till de ljusutledende fibrerna finns en fiberskarv 56 och figur 3a visar ett snitt efter linjen A-A i figur 3.med konfigurationen av de tre fibrerna. Elektroniken skiljer sig i detta fall från det som visas i figur 1 genom att en fyrkantvåg användes i stället för en sinusvåg för modulering av ljuskällan 14. Detta medför, att demoduleringen av skillnadssignalen frân donet 11 kan utföras medelst filtrering i ett filter 60, som är anslutet till donets 11 utgång, faskänslig likriktning i en likriktare 61 och lågpassfiltrerixxg i ett filter 62 för bildande av felsignalen till regulatorn 27. I övrigt är elektroniken uppbyggd så. som visas i figur 1.To get. in light from the second light-conducting fiber 13 to the light-conducting ones the fibers have a fiber joint 56 and figure 3a shows a section along the line A-A i figure 3.with the configuration of the three fibers. The electronics differ in this case from that shown in Figure 1 by using a square wave instead a sine wave for modulating the light source 14. This causes the demodulation of the difference signal from the device 11 can be performed by filtering in a filter 60, which is connected to the output of the device 11, phase sensitive rectification in a rectifier 61 and low-pass filter matrix in a filter 62 for generating the error signal to the controller 27. In other respects, electronics are structured as such. as shown in Figure 1.

I .I.

Claims

In the figures described so far it is shown that two light-emitting fibers are used to transmit information about the measured value. Figure 4 shows an arrangement where only one light-conducting fiber Éa + öb is used for transmitting the measuring signal from the sensor to the measuring electronics. In the sensor itself there is a glass plate 17 which, during its movement in the direction of the double arrow in Fig. 4a by means of a screen 18 arranged on the plate, shields more or less of the light which from the light-initiating fiber 1 the reflecting surface 36 reaches the end of the light-emitting fiber Sa. Since there is no screen in front of the light-conducting fiber 2a, the light reflected into it will not be affected by the movements of the glass plate 17. Figure 4a shows the glass plate 17 with the screen 18 seen perpendicular to From the LED 4, a continuous light is transmitted to the sensor through the fiber 1. The part of this light which is reflected by the mirror 36 into the light-emitting fiber 2a is conducted via a fiber. splice 56 is further passed by the fiber 2b to the photodiode 5, the photocurrent of which is amplified in the amplifier 8 and conducted via a low-pass filter 65 to one. the input of a subtractor 32, where it is compared with a reference sigma Vmf. From the subtractor an error is obtained, which via. The control network 53 is applied to the etyrden 7 of the LED 4, which controls the LED, so that the output signal from the filter 63 is kept equal to Vnf. The light which, after passing past the screen 18, enters the fibers ia is passed through the fiber Bb to the photodiode 6, whose photocurrent is amplified in the amplifiers 9 and 21, and after low-pass filtering in the filter 64 is used as a measuring signal and applied to the measuring instrument 12. Pâ. In the manner shown in connection with Figure 5, the light emitted by the light source 14 and emitted by the fiber 13 is used to control the amplifier 21 via the fibers 2b and Bb, so that the difference between the output signals from the amplifiers 8 and 21 is kept equal to zero with respect to the gear light. through the fiber 13. PATEIVPICRAV

An optical measuring device according to claim 1 in patent 7713207-4 for use in measuring physical quantities and comprising an optical sensor, in which a first light-initiating fiber (1) is arranged to introduce light into the sensor for generating partial a measuring signal and on the one hand a stabilizing signal in the light-emitting fibers (2, 3), characterized in that a second light-conducting fiber (15) is arranged to introduce light into the light-emitting fibers for generating a second stabilizing signal therein. fibers. 7806189-2

2. A device according to claim 1, characterized by devices for forming the difference between the stabilization signals generated by the light from the second light-conducting fiber in the light-conducting fibers, and the use of said signal for controlling the matching between the two. the light-emitting fibers with associated detectors and electronics.

Measuring device according to Claim 1, characterized in that the light in the two light-emitting fibers (1, 15) is mediated with one frequency.

4. A device according to claim 1, characterized in that one of the light-initiating fibers transmits constant light while the other light-initiating fiber transmits light modulated with a certain frequency. _

Measuring device according to Claim 1, characterized in that the light in the light-initiating fibers has a different wavelength. '

6.7 Measuring devices according to claim 1, characterized in that light is introduced alternately into the light-initiating fibers.

Measuring device according to claim 1, containing detectors (8, 9) for detecting - the signals from the light-emitting fibers and converting these signals into electrical signals, characterized in that it contains filter circuits for dividing the electrical signals in a first component derived from the first light-conducting fiber and a second component derived from the second. light-initiating fiber.

Measuring devices according to claim 7, comprising devices for summing the signals from the two. the detectors with respect to. the first. the component and the use of the sum signal as a control signal for the first light-initiating fiber ijuekäiie (4) een / or the detector electronics on. an eedent eätt, that the sum of the detector sigrxals. with respect to. the first component is kept .constant.

Attachments according to claim 7, characterized by devices for forming the difference with respect to. the first component of the signals. from both. the light-emitting fibers and used them. The difference between the signals from the detector devices ((8, 9, '21) with respect to the first component is maintained. constant.7806189-2

Measuring device according to claim 7, k 'a'. n n e t e c k n a. t of devices for forming the sum of the signals from the detectors (8, 9, 21) with respect to. the first component, said sununa being metzigzml.

Measuring device according to claim 7, characterized by devices (11, 29) for forming the difference between the signals from the two detectors. with respect to. the undertaking component, whereby mentioned. difference is a measurement signal.

Measuring device according to claim 7, characterized by devices (18, 19, 20, 23, 24, 25) for forming the difference between detector sigralenza with respect to. the second component and for using said difference to control the vascular ligature of one of the detector circuits so that the difference between the signals from the two detectors. with respect to. the other / component is kept the same. with zero.

Measuring apparatus according to claim 7, characterized by devices for deriving the first component from one of the detector arrays and for using this component as a control array. for the light source of the first light-initiating fiber and / or the detector electronics on. in such a way that said first component is kept constant.

Measuring device according to claim 7, characterized by devices for deriving the first component from one of the detector sigxalenxa, this being a measuring sigxal.

Measuring device according to claim 7, characterized by devices (10, 11) for forming the sum and the difference between the signals from the two detectors (8, 9) with respect to. the first component, and devices (51, 34, 65) for forming the quotient between said sum and sample signals, and that said quotient is applied to the measuring instrument (12) as a measuring signal. MENTIONED PUBLICATIONS: