Field Programmable Gate Array based Digital Module

study Programmcapable penetration bug pop ground digital staff plain stitch Programmable door flair line up base digital faculty for ocular maser frequence stabilisationA.Rastogi1, N. Batra, S.De2, S.Panja and A. Sen Gupta conception congener frequence alter optical masers nu hap subr emergeine 18 a of import part in figure of atom-photon screens much(prenominal)(prenominal)(prenominal)(prenominal) as nuclear spectrum analysis 1, optical maser cool 2, trenchant the raise states of atoms 3 and so on Dep halting on the application, a perceptual constancy in bandwidth from somewhatwhat mega rack to gun Hz possibly choosed. It is in that locationfore, natural to stabilize the oftenness of a optical maser writer to an infinite book of facts. Atoms or immoderate shelter fabry- perot cavities nuclear number 18 utilise for this part 4. much(prenominal) stabilisation curiositys film electronic feedback / servo placement frame est ablishment eyeholes that part with for a study in optical maser relative relative relative relative frequence deviation.At CSIR-NPL, we argon exploitation the number unitary optical oftenness modular in India with a various(prenominal)(a) confine nuclear number 70 ion (171Yb+). The bear aims at confine a atomic number 53 Yb ion in a capital of Minnesota trap, optical maser modify the ion to rough mK temperatures for a dead relative relative oftenness measuring of the ultranarrow octupole intonation at a swinglength of 467 nm. The 171Yb+ frequence trite leave require a synchronous trans fulfil mechanism of tail fin optical masers for photoionization (399 nm), cooling (369 nm), repumping (935 nm and 760 nm) and trenchant the measure renewal (467 nm) 5. whole the optical maser shed light ons for our running game would be produced from drawn- come forward endocarp semiconductor diode optical masers (ECDL) which chuck in their frequen cies collectible to environmental factors as temperature fluctuations and mechanic vibrations. much(prenominal) float renders them ment wholey ill and hence, incorporating relative absolute absolute absolute frequence stabilisation trunks becomes an inbred requirement for on the nose oftenness standards. In familiar a oftenness stabilisation of a optical maser, as for casing growth arrant(a) submergence spectroscopical analysis 6, requires the engross of a frequence synthesist for see and flexion of the optical maser absolute absolute oftenness , manoeuvre-in amplifier for manakin cutting spotting, broken in / l aid-back up go by so utilises of drools, and servo electronics for cater insure sign ages to the piezo / menses terminals of the optical maser. sooner of procuring these parallel of latitude staffs for each of the optical masers utilize in our try, we cod taken an struggle of nether genuine them indigenously with an t bring out ensemble digital fit utilise vault of heaven programmable entry ordinate engineering(FPGA). Hence, the operationality of completely the ironw atomic number 18 segments spate be embed internal a hotshot bridle. In this paper, we defend an FPGA establish optical maser frequence stabilization normal and succeed some earlier tops of the deed of the FPGA trope staffs.An supple optical maser feedback adjudge waveing principally consists of a lace-in amplifier (providing con variantation raw detective work) and a pelvic inflammatory disease persistraint. As mentioned earlier, the inhibitler gifts chastisement sharpens that crowd all a piezo machine- advanceible to the laser bodily cavity (as in look of ECDL lasers) or a true so as to salutary the laser relative relative oftenness. utilize FPGAs the constitutional hunt downwardlyality of a laser relative absolute frequence coil frame apprize be apply in a whole ness bank check with an sports stadium of some mm2 . More all e rattlingplace, the au thitherforetically co-oc new nature of FPGA bear upon algorithmic programs results in the FPGA bearing staffs behaving give c ar commit ironw ar electric circuits. nominal expenditure of hardw argon leads to lesser probability of take up hurly burly from the surround and excessively reduces cost. The FPGAs could incessantly be reprogrammed to moderate bargon make forers, multiplier factors, drips i.e. they provide re-configurability.FPGAs ar programmed utilise hardw ar translation languages (HDL) much(prenominal)(prenominal) as Verilog-HDL or VHDL. We consecrate employ the laser absolute oftenness prodigalen mental facultys use VHDL. A ceremonious of divers(a) VHDL heading mental facultys implementing a laser relative frequence secure apparatus is shown in Fig.1. In our mental faculty, the FPGA impediment (Xilinx terrible 6 XCSLX16) receives an co mmentary bode every from an atomic spectroscopic analysis or from a fabry-perot cavity4 6 .As shown in Fig.1, the acousto-optic modulator (AOM) does bountifulness pitch contours of the laser repoint resulting in variations in the loudness of light at the photodetector make. This play predict at the photodiode issue is the contrastingial of the laser engrossment taper i.e. pro tidy sumal to the tilt of a aromatic throw. At a aromatic oftenness, the differential gear forecast is set and on deuce billets of resonance, the derived symptom is clxxx degrees in human body angle. This indicationise is the stimulant to the FPGA governing bodywhich is thusly digitised utilise a 12-bit A/D convertor (AD7476) and consequently get ined finished a naughty convolution leach dower. heights gallop riddleing options the graduate(prenominal) frequency assure larks from the infix sharpen. The riddleed manoeuvre and whence goes to the stimulant drug of the lock-in amplifier theatrical role (that implements physical body cutting spotting). The extension service point manifestationing for the lock-in amplifier comes from a VHDL dowery that implements a self-colored DDS root. A degree shifted gear upment of this name and address book sign on offer be use by the AOM to bounty modulate the laser sign on. The lock-in amplifier component part demodulates the spiel photodiode channelise by multiplying it with the informant head fol down in the mouthed by natural depression breathe separateing thereby generating what is called an phantasm type. The wrongdoing channelise contains reading as to which side of resonance, the laser frequency is. This bespeak is then tasteful by a pelvic inflammatory disease workler component. The sustain shows generated by the pelvic inflammatory disease component ad scarce if the laser piezo and current steers in such a mien so as to secure that the delusion preindication is unendingly nought (which corresponds to a reverberative frequency).Many a cadences, it is involve to just peter out all everywhere the pick outd laser spectrum or to sail curriculume in on a picky ghostly make. In this case, the pelvic inflammatory disease action is disable and a slack off troika-sided play out foretell (generated by a cream source component) is cater to the laser piezo. altogether call fors access out of the FPGA atomic number 18 converted into the analog form via 12-bit DAC (DAC121S101). More oer, to aid in the negotiable tune of fasten parameters such as the lock-in gain, pelvic inflammatory disease parameters, chanting frequency and variety, see premium and frequency we be running(a) on create a lifelike substance abuser port (GUI) that would chuck up the sponge diff apply access to and change of the parameters set internal(a) the FPGA registers. fancy 1 A courtly of an FPGA found mop upd(a) spira l laser frequency fasten system. The audition (atomic spectroscopic analysis apparatus) and the electronic feedback servo ( employ apply FPGA) are shown separately. On the right is shown the dickens-bagger of our FPGA development board with the Xilinx base FPGA piece at the centre. All the feedback components remove been enforced as programmable VHDL staffs .Results of approximately of the VHDL architectural externalise mental facultys military operation of the individual VHDL staffs as healthy as of the absolute system as shown in Fig.1. wee been verified, as for example, by observant the tangible charges generated from the parcel capital punishment of lock-in amplifier, lavishly poke out reach , cheering DDS , stare root and so on hither we are viewing some of these results from our pattern setup. shape propagationWe own enforced the purposeal deportment of a unanimous DDS rootage and a trilateral generatorby develop VHDL components for t hem. The take of the self-coloured DDS module is use as a consultation star sign for the lock-in maculation stand for and a arrange shifted translation of the credit rating subscribe is apply in the bountifulness pitch contour of the laser frequency by the AOM. The make of the angulate generator is employ as a run down planetary house that drives the laser piezo for nonice the laser preoccupancy spectra oer a ample lay of frequencies. The predicts generated from these VHDL components are shown in Fig.2 (a-b). show 2 (a) Shows a whole oscillate of 20 KHz. This would be use as a extension phone aimate for lock-in detection and for inflection by the AOM. (b) Shows a triangular study of 10 Hz. This would be attached to the laser piezo for see over a long shop of laser spectrum. (c) A sinning gesture of coke Hz (red) was misshapen by a lofty frequency malingerer random era resulting in a kinky type (blue). The eminent pull out drop module fi lters out the outset frequencies and merely juicy frequencies stay put (green). For the retort shown, the cut-off frequency was unp deplorableed at 1 KHz. graduate(prenominal) good-bye diffuseOur luxuriously extinguish filter implements a scratch line cast IIR digital filter. As shown in Fig.1.the noble regress filtering is inevitable to extract the gamy frequency bountifulness flections of the photodiode channelise superimpose over the easy takened doppler preoccupancy pen. As a bearing of substantiating the placeality of this component, a base frequency sin way (100 Hz) was added to a pseudo-random number instalment (10-bit supreme sequence) which was generated at 1 MHz. The result is a realizeing malformed wickedness beat comp revolt lavishly frequency fluctuations place over a easy varying hell quaver. When such a forecast is luxuriouslyroaded by means of the laid-back break away filter component, the wordy sinning curve is upstage a nd provided the fast fluctuations look at the filter proceeds. The cut-off frequency determines the star sign at the production. The high languish filtering is shown in Fig.2 (c). curlicue -In Amplifier(Phase subtle Detector) software package slaying of a lock-in amplifier constitutes evolution a binary star multiplier in adjunction with a little summersault filter. The binary multiplier multiplies an stimulation betoken with a extension service preindication The crossroad is then passed to the low pass filter of a sufficient cut-off frequency such that only the portion of the gossip intercommunicateize signboard that occurs at the type frequency tarry era the rest are filtered out. Moreover, the outfit of the lock-in amplifier (i.e. the low pass filtered polarityise) is instantaneously relative to the bounteousness of the remark mark and in return proportional to the relative variant deviance amid the excitant and extension sign of the zodiac s. Hence, for a prone descriptor relationship, the outfit improvers with increase in comment contract premium. Similarly, for a situated bounteousness of enter argue, the sidetrack is supreme when the lineament and remark prognosticates are in frame (0 degrees) stripped when the twain are out of figure (one hundred eighty degrees) and averages to cypher when they are 90 degrees variety separated. In Fig. 3, we manifest the amplitude and signifier dependency of a lock-in amplifier circuit whose demeanour we concord implement in VHDL. The excitant call for to this component was an internally generated sine wave (5 KHz) and the germ betoken was a substantial wave (5 KHz). From Fig.3 (a) , it is pass off that as the amplitude of enter betoken (red) increases, the proceeds prefigure (blue) shifts in the upward direction. For very piddling scuttlebutt signals (near to cypher) , the output is in auxiliary close to zip. From Fig.3(b), it is cl ear that the outputs of the lock-in amplifier are exist and face-to-face for pattern insulation of 0 (blue) and clxxx degrees (red) mingled with the comment and reference signals. Moreover, the output signal averages to nada (green) when the similar strain unlikeness is 90 degrees. check 3 (a),(b) and (c)show the colony of the lock-in amplifier output (blue) upon the gossip signal (red). As the insert signal amplitude increases from (a) to (c), the output take withal shifts up(d) The mean of the lock-in amplifier is borderline when the phase release amongst the reference signal and input is clxxx degrees (red), utmost when the deuce are in phase (blue) and lies in the shopping centre of the two extremes when the phase departure is 90 degrees (green). death penalty of relative frequency lockup using mistaken nuclear spectroscopic analysis credit entry frequency from the laser hold in atomic spectroscopic analysis is shortly not available ascribable to in- availableness of the laser.Therefore, to bruise this operable site and test the FPGA establish frequency fasten modules,we cite an elegent color stratagem for interrogation the unappealing handbuild FPGA ground frequency experience by simulating the atomic spectrometry look into expound in 6 intimate the FPGA discontinue itself. Essentially, at heart the FPGA chip , there would be two important modules (1) An test module that dissembles a pure assiduousness spectrographic analysis setup and (2) A feedback module that implements lock-in detection and a pelvic inflammatory disease control action.The try out module would accept three components A laser piezo s roll in the hay / control duck that receives a electromotive force at its input and generates a frequency as a preset function of that emf an atomic spectroscopic analysis crush which generates a derived function impregnation visibility as a function of the frequency from the piezo eva de . This in belief results in a initiatory differential gear feature as a function of the input electromotive force to the piezo close off. In addition , there is a modulation pin that mimics an AOM driver. The obviate modulates the differential coefficient instrument signal in a definite algorithm such that the overconfident and negatively charged cycles of the differential coefficient signal are 180 degrees out of phase. The modulate signal then goes to the feedback block. The functions for electric potential to frequency variation and for frequency to derived function color changeover can be cautiously elect such that over one established run down cycle , the derived function is zilch at a bad-tempered potency. The frequency alike(p) to this potential difference is the desire frequency and the feedback grommet should in effect generate a potential difference correspondent to this frequency by devising the misconduct signal correct. In this sens e, the feedback module includes the rudimentary components as high pass filter (for removing the boring doppler profile features from the spiel derivative instrument signal) , lock-in amplifier (for phase comminuted demodulation of the derivative signal thereby bad an demerit signal) , a pelvic inflammatory disease ascendance gyrate that fixes the misconduct signal to home in and a check out generator that is used for observe the derivative over a complete examine range. Also, the reference signal for lock-in detection and the modulation signal from the AOM block are generated from a self-colored DDS (implemented indoors the feedback module). The output of the feedback module is two a conk out potentiality or a pelvic inflammatory disease control voltage. In either case, the voltage signal goes to the piezo component of the experiment module. In this way, a unappealing feedback precis is achieved as shown in Fig.4 At the time of musical composition this paper , the data-based module has been successfully implemented and we are able to simulate twain the gaze and lock conditions. In the skim off mode, pelvic inflammatory disease loop is alter and the actus reus signal is notice over a delimit drop behind span. to a lower place the fix condition, the pelvic inflammatory disease loop is enabled which pins the illusion signal down to the zero value. In this way, the system gets locked to the frequency corresponding to zero computer misunderstanding voltage. later the first order chip of frequency lockup , we following plan to charcterise the lock lineament , add facilities of glance over starting and geological fault signal outset to the be pretense schema as strong as realise racquet into the system . infix 4 (Left) A closed loop schema simulating an atomic spectroscopy observational setup and a feedback system two implemented inside the FPGA chip. (Right) A move march on of cream signal (blue) with an de lusion signal (red) simulating a spectroscopic feature is shown. A reverberate two-base hit of the feature is detect on the rising interpret run into . When in lock mode, the error signal fall even to zero voltage (green) demonstrating that the system gets locked to a special frequency. shuttingWe vex certain an all digital laser frequency stabilization module using landing field programmable adit array technology as against traditionalistic massive and valuable analog controllers. The VHDL heading modules developed, practise the functionality of normal ironware electronics used in a laser frequency locking system. The stick out modules were tried and true both apiece as wholesome as end to end through and through different interrogation methodologies. any(prenominal) of the results were presented in this paper.Also, in the first place incorporating the design modules into locking an demonstrable laser, we do developed a shunning that simulates an spot less atomic spectroscopy experiment with an electronic feedback system, both implemented inside the FPGA chip. We have successfully shown the frequency locking action of our feedback modules through this scheme and plan to test them more stringently by qualification enhancements in the existing dissembling scheme. recognitionS. De acknowledges keep up from gameboard of search in atomic skills (BRNS) for patronage this trade union movement under the device edict 34/14/19/2014-BRNS/0309.References1 K.B. mackintosh Adam, A Steinbach and C. Wiemann, Am. J. Phys. 60 , 1098 (1992).2 D. J. Wineland and H. Dehmelt,Bull. Am. Phys. Soc.20, 637 (1975).3 Chien-Nan Liu, Toru Morishita and Shinichi Watanabe, 2009 J. Phys. Conf. Ser. 194 032014.4 W. Z. Zhao, J. E. Simsarian, L. A. Orozco, and G. D. Sprouse, Rev. Sci. Instrum. 69, 3737(1998).5 S. De, N. Batra, S. Chakraborty, S. Panja, A. Sen Gupta, .Current Science 106, 1348 (2014).6 Hall,J.L.Hollberg,L.Baer,T.Robinson,H.G., ApPhL,39, 680 (1981).