SE190817C1

SE190817C1 -

Info

Publication number: SE190817C1
Authority: SE
Publication date: 1964-01-01

Description

Uppfinnare: M Grosjean Prioritet begtird iron den 29 juni 1960 (Frankrike) Foreliggande uppfinning avser en registrerande apparat for 'matning av cirkular dikroism. Denna apparat kan sasom funktion av vaglangden registrera variationer av skillnaden mellan molekylarabsorptionskoeffieienterna for en dikroisk produkt for cirkulart polariserat vanstervridande ljus, eg, och for cirkulart polariserat hogervridande ljus, Uppmatningen av denna fysikaliska storhet fir av stort intresse f5r bestammande av strukturen av optiskt aktiva produkter, och den nyssnamnda metoden ãr myeket mera effektiv an den metod som utnyttjar dispersionsvridningen. Metodens utveckling har emellertid hittills hindrats genom de myeket stora experirnentella svarigheter som upptra.da vid bestantningar av detta slag. Uppfinningen har till syfte att astadkomma en. praktisk apparat, som tillater en snabb registrering (inom en tid av storleksordningen ett tiotal minuter) av en kurva som anger den cirkulara dikroismen, Eg—Ed, inom det ultravioletta och det synliga omrhdet. Inventor: M Grosjean Priority begtird iron June 29, 1960 (France) The present invention relates to a recording apparatus for feeding circular dichroism. This apparatus, as a function of wavelength, can detect variations in the difference between the molecular absorption coefficients of a dichroic product for circularly polarized left-handed light, eg, and for circularly polarized right-turning light. and the above-mentioned method is much more efficient than the method which utilizes the dispersion twist. The development of the method has, however, hitherto been hindered by the very great experimental responsibilities which have arisen in plantings of this kind. The object of the invention is to provide one. practical apparatus, which allows a rapid registration (within a time of the order of about ten minutes) of a curve indicating the circular dichroism, Eg-Ed, within the ultraviolet and visible range.

Det är kant att en optisk aktiv produkt har olika egenskaper och olika absorption for cirkulart polariserat vanstervridande ljus resp. for cirkulart polariserat hagervridande ljus. Detta medfar dels en vridning av polarisationsplanet for planpolariserat ljus och dels att detta ljus inom absorptionszonen blir elliptiskt. It is edge that an optically active product has different properties and different absorption for circularly polarized left-turning light resp. for circularly polarized hag-turning light. This entails partly a rotation of the polarization plane for plane polarized light and partly that this light within the absorption zone becomes elliptical.

Metoderna far att mata den cirkulfira dikroismen ha nistan samtliga anvant det forhallandet, att vardena pa Ed och ed kunna erhallas ur den nyssnamnda elliptiskheten. Det är emellertid svart att pa lampligt och snabbt satt mata den pa dikroismen beroende ellipsen, eftersom.dennas avvikelse fran cirkeln fir rnycket ringa och aven helt forsvinner i den till- fälligai apparatens olika optiska .delar. The methods used to feed the circular dichroism have almost all used the proposition that the values of Ed and ed can be obtained from the aforementioned ellipticality. However, it is black to feed the elliptical-dependent ellipse in a convenient and fast manner, since its deviation from the circle is slightly small and also disappears completely in the various optical parts of the temporary device.

Uppfinningen bygger pa den cirkulara dikroismens grundegenskap, namligen den olika absorptionen for vanstervridande cirkulart polariserat ljus och far hogervridande cirkulart polariserat ljus. Den optiska anordningen be-star i princip av en intensiv ljuskalla, som stralar mom det ultravioletta och det synliga omradet, en monokromator med kvartsoptik, en. anordning som ger planpolariserat ljus, ett system som kan kallas for en polarisationsmodulator och som med frekvensea f medger onavandling av det planpolariserade Ifuset antingen till ett vanstervridande cirkulart polariserat ljus eller till ett hogervridande eirkulart polariserat ljus under successiv genomgang av mellanliggande elliptiskt polariserade former, en kuvett som innehaller den. aktiva losningen, och en kanslig fotomultiplikator. The invention is based on the basic property of circular dichroism, namely the different absorption of left-turning circularly polarized light and obtaining right-turning circularly polarized light. The optical device consists in principle of an intense light source, which radiates from the ultraviolet and the visible area, a monochromator with quartz optics, a. device which provides planar polarized light, a system which may be called a polarization modulator and which with frequency f allows conversion of the planar polarized Ifuset either to an outwardly rotating circularly polarized light or to a right-turning circularly polarized light during successive passage of intermediate, elliptically polarized light which contains it. active unloading, and a probable photo multiplier.

.Det visar sig att den fran fotomultiplikatorn erhallna utsignalen utgares av en spanning, som innehaller en konstant komposant och en vaxelkomposant med frekvensen f. Den konstanta komposanten har formen KO.) v =+e— Ric) 2 och vaxelkomposanten har formen VA=KO0 (e—egct_e—eact)(cot)/ (2) 2 De ingiende storheterna ha foljande betydelser: 0„ det ratlinjigt polariserade monokromatiska ijusflodet K fotomultiplikatorns omvandlingskoeffident Ed, Ed molekylarabsorptionskoefficienterna; angivna som .exponenter av basen e C molekylarkoncentrationen (1) 2— — 1 vatskelosningens tjocklek I genomgangsriktningen f (wt) en funktion av frekvensen, med en form beroende ph den moduleringstyp som anvants = 271f. It turns out that the output signal obtained from the photomultiplier is emitted by a voltage containing a constant component and a gear component with the frequency f. The constant component has the form KO.) V = + e— Ric) 2 and the gear component has the form VA = KO0 (e — egct_e — eact) (cot) / (2) 2 The constituent quantities have the following meanings: 0 „the linearly polarized monochromatic light flood K the conversion coefficient of the photomultiplier Ed, Ed the molecular absorption coefficients; given as .exponents of the base e C molecular concentration (1) 2— - 1 thickness of the liquid solution In the passage direction f (wt) a function of the frequency, with a shape dependent ph the type of modulation used = 271f.

Det är latt att ph elektronisk vag skilja de Edda kornposanterna frhn varandra. It is easy for ph electronic vague to separate the Edda grain possessors from each other.

Vaxelkomposanten farstarkes av en forstarhare, som utan distorsion slapper igenom frekvenser upp till aminstane 5 f, varefter en likriktning sker genom en helvaglikriktare synkront med matningsspanningen for systemet for den cirkulara polarisationen. Den likriktade signalen, vilken Or proportionell med e–Ego_ e–mo matas darefter till ingfingen i en registrerande anordning av potentiometertyp. The gear component is amplified by a preamble hare, which without distortion passes through frequencies up to aminstane 5 f, after which a rectification takes place through a full-wave rectifier synchronous with the supply voltage of the system for the circular polarization. The rectified signal, which Or proportional to e – Ego_ e – mo is then fed to the finger in a potentiometer type recording device.

Likspanningen phlagges Over motstandselementet i den potentiometer som inghr i registreringsanordningen, sedan den bringats till symmetrisk form i avseende ph jord eller »gods», sh att potentiometerns mittpunkt kornmer att ha spanningen 0, under det att ytter- Vc punkterna ligga p. spanningen— resp. 2 — Vc/2. The DC voltage is phlagged over the resistive element of the potentiometer included in the recording device, after it has been brought into symmetrical shape with respect to ph earth or «goods», sh that the center of the potentiometer is to have the voltage 0, while the outer Vc points lie on the voltage— resp. . 2 - Vc / 2.

Under dessa forhallanden Or visarutslaget i registreringsanordningen proportionellt med (6g-8a)C1 for smh. varden ph storheten (ggga)G1, och dikroismens tecken liar hven bibehallits. Under these conditions Or the reading result in the recording device proportional to (6g-8a) C1 for smh. the value ph the size (ggga) G1, and the signs of dichroism liar hven maintained.

Uppfinningen beskrives narmare i samband med bifogade ritningar. Fig. 1 visar sasom exempel en utfOringsform av uppfinningen, i schematisk framstallning. Fig. 2 Or ett kopplingsschema fOr matanordningen. Fig. 3 Or en schematisk vy av en modifikation av polarisationsmodulatorn. Fig. 4 visar en annan modifikation av polarisationsmodulatorn. Fig. 5 visar schernatigkt en tredje modifikation, som kan tillampas vid de i fig. 1 och 4 visade an.- ordningarna med fast polarisator. The invention is described in more detail in connection with the accompanying drawings. Fig. 1 shows, by way of example, an embodiment of the invention, in schematic representation. Fig. 2 Or a wiring diagram for the feeding device. Fig. 3 Or a schematic view of a modification of the polarization modulator. Fig. 4 shows another modification of the polarization modulator. Fig. 5 schematically shows a third modification which can be applied to the fixed polarizer devices shown in Figs. 1 and 4.

Den i fig. 1 visade anordningen, som utgor ett exempel, anvandes en ljuskalla 1, som kan utgoras av en i vate eller argon brinnande ljusbage, som matas air en stabiliserad likstroms- Ljuset riktas medelst speglar mu1, m2 mot en ingangsspalt 2 i en monokromator 3, som har kvartsoptik och exempelvis utgOres av .den med Beckman DU betecknade typen, varvid axeln a i dispersionssystemet drives av en synkronmotor. En blandare 5 anligger mot en utgangsspalt 6 och tjanar som monokromatisk ljuskalla for den aterstaende delen av apparaten. Ljusstralarna fran denna kalla bringas att bli parallella med varandra genom en Has 7 av kvarts och gO darefter genom ett Rochon-prisma 8, hvenledes av kvarts. Det extraordinara stralknippet, fe, elimineras genom en blandare 9, som Or belagen ph lampligt shit, och den ordinara strhlen, f. gar genom en kristall 10, som r utskuren p0 lampligt &hit ur ett amne med Pockel-effekt (exempelvis en In onokristall av ammoniummonofosfat). The device shown in Fig. 1, which is an example, is used a light source 1, which can be constituted by a candle bag burning in cotton or argon, which is fed into a stabilized direct current. The light is directed by means of mirrors mu1, m2 towards an input slot 2 in a monochromator 3, which has quartz optics and is, for example, of the type designated Beckman DU, the shaft of the dispersion system being driven by a synchronous motor. A mixer 5 abuts against an output slot 6 and serves as a monochromatic light source for the remaining part of the apparatus. The light rays from this cold are made to become parallel to each other by a Has 7 of quartz and then by a Rochon prism 8, also of quartz. The extraordinary beam, fe, is eliminated by a mixer 9, which Or coated ph suitable shit, and the ordinary beam, f. Passes through a crystal 10, which is excised p0 suitable & hit from a subject with Pockel effect (e.g. an In onocrystal of ammonium monophosphate).

En vaxelspanning med en frekvens air 50-Hz palagges tvh metallelektroder 11, vilka Ore anbragta mot de hada sidorna av kristallplattan 10. I den riktning, i vilken ljusstralarna gh. genom plattan, uppstar harigenom en dubbelbrytning, vilken blir desto storre ju storre den palagda sphnningen Kristallplattan 10 Or monterad ph sadant satt, att huvudsnitten ligga i 45° vinkel mot det infallande ljusets f. polarisationsplan. Det planpolariserade ljuset kommer da att uppvisa en elliptisk form, som blir alltmera utpraglad under loppet av en period och slutar med eirkular polarisation, om spOnningens maximivarde Or raft installt. P0 grund av att Pockel-effekten beror ph det elektriska faltets riktning, erhalles successivt ljus som Or vanstervridande och ljus som Or hOgervridande. An alternating voltage with a frequency of air 50-Hz is applied to two metal electrodes 11, which Ore arranged against the hot sides of the crystal plate 10. In the direction in which the light rays gh. through the plate, a birefringence arises, which becomes all the greater the greater the applied voltage. The crystal plate 10 is mounted so that the main sections are at a 45 ° angle to the plane of incidence of the incident light. The plane-polarized light will then have an elliptical shape, which becomes more and more emitted over the course of a period and ends with circular motion, if the maximum value of the voltage is installed. Due to the fact that the Pockel effect depends on the direction of the electric field, light is obtained as Or left-turning and light as Or right-turning.

Vid denna modulator kommer den i formeln (2) ingdende funktionen f (wt) att antaga for-men 60 sinwt, dar bo utgiir den genom kristallplattan ,erhallna fordrojningsvinkeln vid matningsgpanningens (exciteringsspanningens) rnaximala varde. In this modulator, the function f (wt) contained in the formula (2) will assume the shape 60 sinwt, where bo emits the displacement angle obtained through the crystal plate at the maximum value of the supply voltage (excitation voltage).

'Det p0 detta satt polariserade ljusknippet passerar darefter genom kuvetten 12, som innehaller den aktiva produkten. Kuvetten Or forsedd med plana och parallella sidor, vilka utgOras av kvartsplattor. Ljusknippet fallar slutligen ph en for ultravioletta strhlar Trans-Jig fotomultiplikator 13, exempelvis av typen 1 P 28. FotomultiplikatorrOret 13 efterfoljes av en likspfinningsforstarkare A. (se fig. 2), som utgor ett skiljesteg. The thus polarized light beam then passes through the cuvette 12, which contains the active product. The cuvette Or is provided with flat and parallel sides, which consist of quartz plates. The beam of light finally falls on an ultraviolet beam Trans-Jig photomultiplier 13, for example of type 1 P 28. The photomultiplier tube 13 is followed by a DC amplifier A. (see Fig. 2), which constitutes an isolation stage.

Vaxelspanningskomposanten V, med trekvensen f uttages frhn forstarkarens A. ,utgang och forstarkes av en forstarkare A, (se fig. 2) samt likriktas i en detektor A2 air helvaglikriktande och synkron typ, som matas i fas med den matningsspanning som palagges kristallplattan 10. Den detekterade sphnningen betecknas med Va. The alternating voltage component V, with the frequency f, is taken from the output of the amplifier A. and amplified by an amplifier A (see Fig. 2) and rectified in a detector A2 air fully rectifying and synchronous type, which is supplied in phase with the supply voltage applied to the crystal plate 10. The detected voltage is denoted by Va.

Det anvanda detekteringssystemet tillater att fotomultiplikatorns storande brus kan nedbringas i storsta mojliga grad. For att man shall erhalla st8rsta mOjliga detektera.de signal Or det nodvandigt att utnyttj a en fordrojningsvinkel eller efterslapning 60, som Or stone On n/2. Till fOljd harav kommer man att vid maximal modulering overskrida en kvarts vh.glangd. The detection system used allows the interfering noise of the photomultiplier to be reduced to the greatest possible extent. In order to obtain the largest possible detectable signal, it is necessary to use a displacement angle or lag 60, such as Or stone On n / 2. As a result, at a maximum modulation, a quarter vh.glangd will be exceeded.

Den likspanningskomposant Vc, som uttages frail forstarkaren A0, bringas att ligga symmetriskt i forhallande till »gods» i en forstarkare As med stor negativ hterkoppling (innefattande ett katodfoljarsteg) oak palagges darefter p0 motstandselementet i en i registreringsanordningen E inghende potentiometer. Spanningen V ph potentiometerns rOrliga arm — —3 C jamfores med den detekterade spfinningen Vd. Den darvid erhallna skillnaden forstarkes i en forstarkare A4 och far paverka en motor M, farbunden med den rorliga armen C me-deist en transmission, som bildas av en linskiva p och en tunn lina c1, Aiken pft samma gang paverkar en skrivspets s i registreringsanordningen. Anordningen arbetar pa sadant satt att den nyssnamnda spanningsskillnaden praktiskt taget halles vid Harigenom kornmer fi5rhallandet mellan vaxelspanningskomposa.nten och likspanningskamposanten att upptecknas, och detta forhallande är proportionellt med (sg—sd)C1, om denna storhet dr mycket liten. The direct voltage component Vc, which is taken from the amplifier A0, is made to lie symmetrically in relation to the "goods" in an amplifier As with a large negative feedback (including a cathode follower stage) and then applied to the resistor element in a potentiometer included in the recording device E. The voltage V ph of the potentiometer'sROrliga arm - —3 C is compared with the detected voltage Vd. The difference thus obtained is amplified in an amplifier A4 and is allowed to actuate a motor M connected to the movable arm C by means of a transmission formed by a pulley p and a thin line c1. The device operates in such a way that the aforementioned voltage difference is practically kept at Harigenom, so that the ratio between the alternating voltage component and the direct voltage component is recorded, and this ratio is proportional to (sg-sd) C1, if this quantity is very small.

F8r att registreringsanordningen skall fungera pa ratt satt for alla vaglangder jamfores likspanningskamposanten vid forstarkarens Ao utgang (se fig. 2) ,med en fast spanning, och detta sker medelst en fOrstarkare A, som medelst en motor M2 (se fig. 1 och 2) paverkar spalterna 2 och 6 (se fig. 1) i monokromatorn pa sadant salt att likspanningskomposanten bibehalles konstant. In order for the recording device to function properly for all wavelengths, the DC compositor at the output of the amplifier Ao (see Fig. 2) is compared with a fixed voltage, and this is done by means of an amplifier A, as by means of a motor M2 (see Figs. 1 and 2). affects slots 2 and 6 (see Fig. 1) in the monochromator on such salt that the DC component is kept constant.

Storheten O. bibehalles vidare konstant inom den a-vsedda delen av ljusspektret genom reglering av den vaxelspanning som palagges modulatorn 10-11 enligt en funktion av Vaglangden, och detta utfores med tillhj alp av en spanningsregulator 14 (fig. 1), som ar kopplad till axeln ph den motor 4, som driver monokromatorn 3. The quantity O. is further maintained constant within the unseen part of the light spectrum by regulating the alternating voltage applied to the modulator 10-11 according to a function of the Vaglangden, and this is carried out with the aid of a voltage regulator 14 (Fig. 1), which is connected to the axis ph the motor 4, which drives the monochromator 3.

Den nu beskrivna anordningen medger registrering eller uppteckning av dikroismen Mom det synliga och det ultravioletta omradet. The device now described allows the registration or recording of the dichroism Mom the visible and the ultraviolet area.

Vid en i fig. 3 visad modifikation har den med en kristall arbetande modulatorn ersatts av en anordning med ett polariserande prisma 15, som vrider sig med en frekvens av f/2, och ett Fresnel-prisma av kvartsvagtyp och utfort av kvarts. Polarisationsplanet for det ljus som faller pa Fresnel-prismat antar successivt, under lappet av en period, alla riktningar, och det frail prismat utgfiende ljuset gar fran hogervridande cirkulart polariserat ljus Over alla grader av elliptiskhet till vanstervridande cirkulart polariserat ljus under ett kvarts vary. Den i formeln (2) ingaende funktionen f (wt) fir lika med cot. Av rent mekaniska skal är frekvensen f mycket lagre an vid den foregaende anordningen och ligger i narheten av 20 Hz, vilket motsvarar 10 vary per sekund av polarisatorn. In a modification shown in Fig. 3, the crystal modulator has been replaced by a device with a polarizing prism 15, which rotates at a frequency of f / 2, and a quartz wave type Fresnel prism and made of quartz. The plane of polarization of the light falling on the Fresnel prism successively assumes, over the course of a period, all directions, and the free prism emitting light goes from right-turning circular polarized light over all degrees of ellipticity to left-turning circular polarized light for a quarter of a minute. The function f (wt) given in formula (2) is equal to cot. Of purely mechanical shells, the frequency f is much lower than in the previous device and is in the vicinity of 20 Hz, which corresponds to 10 varies per second of the polarizer.

Vid en andra modifikation (se fig. 1) fir polarisatorn 8 fast, men det planpolariserade ljuset gar genom ett magnetooptiskt system 17, 18, som har Faraday-effekt, innan det gar genom Fresnel-prismat 16. Det magnetoop tiska systemet tillater att ljusets polarisationsplan svanger omkring ett medellage med en vinkel ao = + 45°. Det bestar av en kuvett 18 med sidor, som fir genomtrangliga for ultraviolett ljus, och kuvetten ar fylld med en lamplig vitska, som aven slapper igenom ultraviolett straining, och är placerad langs axeln i en spole 17, genom vilken en vaxelstrom med frekvensen f passerar. Utan strommatning av spolen 17 installes polarisatorn pa sadant satt, att polarisationsplanet ar parallellt med en neutrallinje i Fresnelinismat 16. Vid lamplig installning av stromstyrkan kommer en Over-gang frail vanstervridande ljus till hogervridenda ljus att ske mom en halv period. Den aterstaende delen av anlaggningen är lika med den forut beskrivna. Den i formeln (2) angivna funktionen f (wt) har formen 2a0sinwt. In a second modification (see Fig. 1), the polarizer 8 is fixed, but the planar polarized light passes through a magneto-optical system 17, 18, which has a Faraday effect, before passing through the Fresnel prism 16. The magneto-optical system allows the light polarization plane orbits about an average layer with an angle α = + 45 °. It consists of a cuvette 18 with sides which are permeable to ultraviolet light, and the cuvette is filled with a lampshade, which also passes through ultraviolet straining, and is placed along the shaft in a coil 17, through which an alternating current with the frequency f passes . Without current supply to the coil 17, the polarizer is installed in such a way that the plane of polarization is parallel to a neutral line in Fresnelinismat 16. With suitable installation of the current, a transition from left-hand turning light to right-turning light will take place in half a period. The remaining part of the plant is equal to that previously described. The function f (wt) specified in formula (2) has the form 2a0sinwt.

Det fait som spolen 17 skall lamna är mycket kraftigt och ,det ar darfor nodvandigt att en mycket kraftig kylning av spolen sker. The fact that the coil 17 is to leave is very strong and, therefore, it is necessary for a very strong cooling of the coil to take place.

En tredje modifikation visas i fig. 5 och kan tillampas vid sadana anordningar som ha en. fast polarisator, d. v. s. sadana som visas i fig. 1 och 4, och harvid placeras mellan polarisatarn och moduleringssystemet 10, 11 en magnetooptisk cell 19, 20 av Faraday-typ och en polarisator 21, vars polarisationsplan ligger i 0 vinkel mot den fiirsta polarisatorns polarisationsplan. Den for Faraday-cellen erforderliga spolen 20 matas med lflmplig vaxelstrom och lamnar efter forstarkning fotosignalens vaxelspanningskomposant. Str8mmens faslage valj es pa sadant salt, att vridningen air polarisationsplanet genom den magnetooptiska cellen astadkommer en variation av frail den andra polarisatorns utgang som flr lika stor och liar samma tecken som det som harror fran dikroismen i lOsningen, nar forstarkningsfaktorn for den forstarkare som forbinder Faraday-strommen med fotocellens utgangsvaxelspanning är tillrackligt stor .for att den sistnamnda vid jamvikt skall kunna anses Tara praktiskt taget lika med noll. A third modification is shown in Fig. 5 and can be applied to such devices having one. fixed polarizer, i.e. those shown in Figs. 1 and 4, thereby placing between the polarizer and the modulation system 10, 11 a Faraday type magneto-optical cell 19, 20 and a polarizer 21, the polarization plane of which is at an angle to the polarization plane of the first polarizer. . The coil 20 required for the Faraday cell is supplied with flexible alternating current and, after amplification, leaves the alternating voltage component of the photo signal. The phase of the current is chosen on such a salt that the rotation of the plane of polarization through the magneto-optical cell produces a variation of the output of the second polarizer which is as large and has the same sign as that of the dichroism in the solution, when the gain of the amplifier connecting Faraday the current with the output shaft voltage of the photocell is sufficiently large that the latter at equilibrium can be considered Tara practically equal to zero.

Under dessa forhallanden visar det sig att for sma varden pa storheten (sg—sd),G1 strommen genom spolen 20 am proportionell med den cirkulara dikroismen. Derma strom omvandlas till spanning genom att ledas genom ett motstand 22, varefter den uppkomna och med storheten (8.—s.) Cl proportionella spanningen likriktas i en synkron likriktare 23 och darefter upptecknas genom anvandande av en skrivande voltmeter av kand typ. Under these conditions it turns out that for small values of magnitude (sg — sd), the G1 current through the coil is 20 am proportional to the circular dichroism. This current is converted into voltage by being passed through a resistor 22, after which the voltage generated and proportional to the magnitude (8.-s.) C1 is rectified in a synchronous rectifier 23 and then recorded by using a type voltmeter.

Claims

Patent claim:

Apparatus for feeding circular dichroism of an optically active substance, characterized in that the apparatus comprises a light source (1), a device (3) for converting the light into a monochromatic beam of varying wavelength, a polarizer (8, 15) for to polarize this beam, a second device (10, 11) is allowed to modulate the polarization of the beam and alternately provide a counter-rotating polarized beam and a right-turning polarized beam, in order to provide a direct 4 - - electro-optical determination of the difference between resp. a wind-rotating polarized light third device (13), which comprises a photoelectric means (13) for determining the intensity of the light beam after passage through the object, saint a recording system which is controllable by means of the third device for recording said difference between the absorption of . left-turning polarized light as a function of its wavelength.

Apparatus according to claim 1, characterized in that the photoelectric means is provided by a photomultiplier (13).

Apparatus according to claim 1 or 2, characterized in that the device (3) for converting the light from the light source (1) into a monochromatic beam comprising an optical, monochromatic device of quartz oil with a grating.

4. Apparatus according to claims 1-3, characterized in that the modulating device (10, 11) has a Pockel effect and can be actuated by means of alternating current.

Apparatus according to any one of claims 1-3, characterized in that the modulation device for the light beam comprises a rotating polarizer (15) and a Fresnel price: ma.

Apparatus according to any one of claims 1-3, defined by the modulating device comprising a Fresnel prism (16) and a magneto-optical Faraday cell (17, 18).

Apparatus according to any one of claims 1-5, characterized in that the third device (13) comprises means for separating an alternating voltage component on the output side of the photoelectric means (13) from a direct voltage component, means for amplifying and rectifying the alternating voltage component and a device comparative mat-fling air father the rectified component and said DC voltage component.

Apparatus according to claim 7, characterized in that the device (3) is generated by the monochromatic beam Sr provided with slits, which are adjustable by means of a servomechanism, which operates depending on the voltage difference between the direct voltage component and a standard spinning, the direct voltage component being kept constant. Request publications: