FR2692361A1 - Method and device for occulting disturbing targets for missile guidance and tracking devices. - Google Patents

Abstract

The invention relates to a method and a device for occulting disruptive targets for a missile guidance and tracking apparatus, comprising a occluding diaphragm, made of two discs (1, 2) adjustable by rotation, placed one behind the device. another coaxially with the line of sight and each comprising a slot (12, 13) going from its center (coinciding with the line of sight) to its periphery, the intersection of the two slots produced by the rotation of the discs revealing an opening of diaphragm (18) making it possible to capture the image of the missile after its departure and to bring it (by continuing the rotation of the discs) into the central window (17) of the diaphragm through which the line of sight passes, the drift thus observed used to correct the trajectory of the missile.

Description

The present invention relates to a concealment method and device

  disruptive targets in the focal plane of a missile guidance device by means of a mechanical diaphragm which only allow the image of the image to form on a detector placed behind the focal plane after the missile has left radiant energy of the image area proper and that of its immediate vicinity, energy previously modulated at a constant frequency in the focal plane, so that a drift of the missile from the optical axis produces a deviation

  sinusoidal from the mean frequency, called excursion of

  quence Af, representing the measurement of the drift r of the missile from the optical axis, while the phase shift in time b of the passage to zero of the frequency excursion will represent the measurement of the

  angular position e in the polar coordinate system.

  Such a method and the device suitable for putting it into practice are described, essentially, in the published German patent application N O 26 55 306 This further indicates that the minimum dimensions of the diaphragm depend on the precision of the signals of

  output of the measuring device, of the maneuverability of the missile, and of

  external spaces such as the directional movements of the device.

  On the other hand, it does not give indications on the conformation of this diaphragm nor on the multiplicity of the possibilities of application The determination, claimed in this patent application, of the drift

  (or angular deviation of a missile from a reference direction

  rence) using the thermal energy it radiates, is dealt with in the published German patent application N O 11 91 119 and in the patent

German NO 13 03 486.

  The object of the present invention is to allow the diaphragm of the process and the device in question to be brought exactly and quickly into the tracking position according to the instantaneous position of the

missile in the image field.

  This object is achieved, in accordance with the invention by the fact that a) the angular position O of the missile and the excursion of frequency t f are divided into equal angular steps; b) the diaphragm used consists of at least two slotted discs arranged one behind the other and coaxially in the center of the focal plane; c) the discs are offset so as to generate at least one zone of intersection of the slots which can constitute a diaphragm opening; d) the aperture of the diaphragm is brought into coincidence with the image of the radiant energy of the missile in the focal plane; e) the drift signals guiding the missile are used to control the slotted discs so that by continuing to rotate the

  discs the missile is brought in, as well as the opening of the slide

  phragm, in the center, not obscured by the diaphragm, of the focal plane. Such a diaphragm is simple and relatively inexpensive to produce, and can be mounted, protected from shocks and vibrations, on

  land vehicles and flying machines, and lend themselves to the

  following a missile with precision and speed.

  According to a development of the invention, the division of the angular position G and of the frequency excursion to f in equal steps makes it possible to bring the aperture of the diaphragm to any point of the image field by rotation of the first disc of an angle -on and the second disc of this angle plus or minus the depth angle

  pn We will therefore obtain the desired position of the diaphragm in effect

  simply killing an addition or subtraction of the primary measures

  mayors O and p These are the operations most quickly carried out in an electronic calculator, in addition to saving the transit time in the processing electronics of the modulation device and

  that the inaccuracies of the conversion to map coordinates be eliminated

  hers. The principle according to the invention may be applied, for example, to a tracking device by pointing the center, not obscured by the diaphragm, on a fixed irradiating target such as a fixed star, and by determining independently, with the diaphragm opening, the relative position of a missile, by positions O and p, to obtain from the two goals drift signals chronologically separated one

  on the other In such a case, the rest of the firmament will be hidden.

  In the above case, it will be appropriate to use, jointly

  to the two slotted discs, a third disc passing alternately

  the radiation of the two irradiating targets and whose axis of rotation will be offset from the value "e", the angular position of this

  Q 5 eccentricity being related to the angular position (On of the missile.

  An advantageous development of this method makes it possible to simultaneously guide two missiles on separate targets, by guiding towards its target the first missile, covered by the third disc and protected against the environment by the opening of the diaphragm, and brought into the central point. not obscured, that is to say in the line of sight, by launching in parallel, on a predetermined lateral waiting trajectory, a second missile protected by the diaphragm then released, keeping it there until impact of the first missile on the first target, then targeting a second target, removing the predetermined waiting trajectory and finally bringing the second missile into the line of sight, that is to say on the target intended for it , and then launching in parallel a third then a

  fourth missile and so on.

  It is also conceivable to engage the modulator and to bring the two slotted discs into rotation to a standby position.

  previously programmed corresponding to the planned missile input.

  Regarding the conformation of the diaphragm of the dispo-

  sitive according to the invention, it will be advantageous if the discs which compose it are circular and each have a slot going from their common center to their periphery by a different path, one of them having the shape of a sector of a circle and the other a spiral shape, the common center of the two discs having the shape of an essentially circular window, through which the image of the point targeted and

  from its immediate environment will form on the focal plane.

  In the case of tracking devices in which the drift voltages obtained serve to automatically bring the missile back on the line of sight, no emitter of disturbing radiation should appear in this window, which should constitute the opening of

  diaphragm after straightening the trajectory of the missile.

  With regard to the dimensions of the spiral, it will be advantageous if the radial increase -of the spiral -corresponds to the distance from the image center r = focal distance t and the angular increase to the variation of l frequency excursion A f It may sometimes be advantageous to use, instead of a slotted disc in

  circular sector, a disc with an inversely symmetrical slot

stick to the spiral slot.

  When the missile drift is large, the sinu shape

  the frequency amplitude is deformed As a result, the measurement of the angular position O deviates from its theoretical value 6 th This difference in phase shift cf depends on the drift r and its correction requires complicated calculations including the present invention takes into account by bending the two slits so that their curvature in the focal plane is increased or decreased by a corrective factor or In the particular case above, with two transmitters of

  active radiation in the image field, the eccentricity of the axis of rotation

  tion of the third disc must be at least equal to half the

  diameter of the fixed radiation emitter.

  It will be advantageous if the drive of the circular slotted discs is ensured, either by gear wheels set

  works by stepping motor or by continuous drive

  carrying a motor and a tachogenerator, either by a transmission by friction plates or by belts The starting position should be indexed at G = 00 It will also be advisable that a point

  precision of the periphery of the slotted disc or of the top of the corresponding tooth

  laying down be made reflective and that a light barrier photocell coming into action at this position be installed opposite

  start to bring a counter to zero.

  Another characteristic of the invention provides for adding to the slots of comparatively large dimensions of the discs, a tight network of slots forming a grid, arranged in opposite directions and having the form of involutes regularly spaced, and of a width corresponding only to a few hundredths apart

  separating This network may occupy, on the slit disk, an over-

  annular face concentric with the latter or, in the event of a rapid recall of the missile in the center of the image field, occupy the entire surface

  of the disc except that of the slots.

  According to a particular and characteristic embodiment of the device, the first slit discs, as well as the second slit discs, of at least two diaphragms are coupled by a toothed wheel, the slit discs of one of the diaphragms each being coupled to a stepping motor by a gear, while the slit discs of the other diaphragm each cooperate with a barrier photocell The slit discs can be

  of different or equal diameters and will be fixed on the bottom of my-

  tures, essentially bushel-shaped and joined together by a

  double ball bearings, held in a housing.

  The invention is described below in detail with reference to some preferred, nonlimiting examples of embodiment shown in the accompanying drawings in which the same parts have the same reference numbers, and in which: Figure 1 shows the principle traditional modulation of the energy irradiated by a target set in motion in order to determine its drift from the line of sight; FIG. 2 represents the relation existing between a constant frequency modulation according to FIG. 1 and the sinusoidal deviation produced by the drift of the target;

  Figure 3 shows the traditional conversion to coordinate

  Cartesian born of drift signals expressed in coordinate

  polar born; FIG. 4a represents the first disc (with radial slot) of the diaphragm according to the invention, (in this figure, as in FIGS. 4b, 5, 8, 9, 11 and 12, the large numbers indicate the position angular taken in each case as

example);

  Figure 4b shows the second disc (spiral slot) of the diaphragm according to the invention; Figure Sa shows the cooperation of the two slotted discs of Figures 4a and 4b; FIG. 5 b represents the cooperation of the spiral slit disc of FIG. 4 b with an identical disc symmetrically inverted with respect to the first FIG. 6 represents the difference between the angular position measured 9 and the theoretical angular position O th produced by the deformation sinusoid in case of strong drifts; Figure 7 shows the relationship between the phase shift in Figure 6 and the 'Ir "drift of the missile from the crosshairs; Figure 8 a shows the radial slit in Figure 4 corrected according to the phase shift in Figures 6 and 7 ; Figure 8b shows the spiral slot of Figure 4b corrected according to the phase shift of Figures 6 and 7;

  Figure 8 c shows the spiral slot of Figure 4 b symmetri-

  only reversed; FIG. 9 a represents the cooperation of the two discs with corrected curved slots of FIGS. 8 a and 8 b; FIG. 9 b represents the cooperation of the two discs with corrected curved slots in FIGS. 8 b and 8 c; Figure 9 c shows the cooperation of the two slotted discs

  with corrected curvatures of FIGS. 8 a and 8 c ;.

  FIG. 10 represents an additional disk for the central window visible in FIGS. 5 and 9; Figures 11a to 11c show the slotted discs of Figures 8a to 8c provided with a tight network of grid slots; FIG. 12 represents a combination of discs according to FIGS. 11 b and 11 c, the slots of which are in the so-called "waiting" position; FIGS. 13 a and 13 b represent the relationships between the drifts "r", the angles of correction of the slits "I p", the magnification ratio fi, of two objectives, and the angle of depth II f ", in modulator systems with two different picture angles switchable with each other; FIG. 14 a represents the basic arrangement of the device according to the invention, in section along the line AB of FIG. 14 b FIG. 14 b is a top view of the device of FIG. 14 a, without cover, and

  FIG. 15 is a section, longitudinally stretched, of the device

  tif along line CD in Figure 14 b.

  When several irradiating or reflecting elements 6 are in the field 5 of a viewfinder not shown in detail, as shown in FIG. 1, and these elements project, towards the viewfinder a comparable or stronger radiant energy, the position of the most powerful energy source, that is to say the center of gravity of energy To eliminate these disturbing emitters we have, after determining the initial position of the useful irradiating element in the field of image, a diaphragm (which will be described later) at the place where it covers the rest of the field In the example described, this useful irradiating element consists of a missile launched

from a launching pad.

  The diaphragm may be placed in front of the focal plane so that the energy of the disturbing transmitters cannot fall on the modulating disk 7 moving along W 1 and W 2 on the radius R But this diaphragm can also be placed behind the focal plane -In both cases, only the modulated radiation, passing through the aperture of the diaphragm, reaches the detector (not shown) The measurement, now undisturbed, of the position of the useful irradiating element as well as that of its displacements possible with respect to line of sight 8 coinciding with the center of field 5 can be used to

  the diaphragm pursuit action.

  The dimensions of the diaphragm depend on the precision of the starting signals from the measuring device, the maneuverability of the missile and external influences such as the directional movements of the measuring device. Furthermore, the precision of the adjustment of the diaphragm over face value and consider the

  maneuverability as a function of the diaphragm tracking speed.

  In this modulation system known per se, the energy

  diante of a target placed on the optical axis, is, as shown in Figure 2, modulated at a constant frequency by the modulating disk Ise snss Sp-1 il J Dap Jnalelnpow awa is As np; Bl Jelnfli Jed el u J + u uo 14 sod el e, uawe a J 3 e J ^ ap anbsip al 'qs a Jn 615 el aluasada J al awwoo' aas Ja \ ul i uawanbl J ew s úL aeuej aun aa 6 euaw: sa lanbal suep ú anbslp al Da Ae aulqwo D -, sa Z anbslp el i S du ap Z anbsip el ae ap L anbslp al Jau Jnol ueslej ua (L a Jn 615) S dwe 4 o np uiod lanb a B Jodwl, u ue aw 5 e J 4 delp ap 9 Jn: l Ja \ n O, l Jiuawe Os

  eujnod uo 'u xne 6 a sa Jlelnlue sed ua _ 4 aouanba J 4 ap uols Jn Dxa, l l.

  a Jleln 6 Ue uoillsod el a Sl Alp UO DU Op IS SL aw 6 e J Ldelp ap a Jnl Jafno aun aei: e Jedde: uuasslel i: e S an 615; el aluasa Jda J el awwo D uaslo JD as se: Lua 4 xnep s Jnal enb uo 5 e; op uoi: eio J ue xnap sno siw a Ji: B luaf ^ nad sll 'a Bl J 2 ap uoét el ap sesodslp 1 uos sanbslp sa anbs Jo 5 Z -; V Duenbe Jj; ap Uol S Jn 2 xxa, l p Uolpel Je A el e puod -sa J Jo 2 a Jlein 6 ue - uewasslo JD: e, l uop a 'dwe 4 D np a Jlua Df np, ale Do; a Buelslp / J = J ,, lueweu 61 olp uos e puodsa J Jo 2 lelpei -uewasslo JD 3 e, l 1.uop EL ale Jlds a ua 4 aun a B Jodwo 3 z enbslp el 'BJ 1 uo 2 Jed -elqesuad -slpul Jne 56 Jel al; ad snld el 'enbslp np uo Sej np i ulod enbe 4 p jnod' e oz a Jnl Ja- ^ no, l I uop LL alelpe J uae aun al Jodwoz L anbslp 8 (L a Jn 61 ;) 9 le J: lua ulod ne-: uawelelxeo D 'le Do; ueld np sed a Ji ne, Jal J Jap un, j sa Deld la '(e 17 L e Jnll_) unwwo) uo 11 e 1 o J ap ax un Jns uewuenbl J 1 -, aw As sae: luow' 8 E e LZ sa Jn: uow sap suep 'gpa Do Jd a Jfne no a 6 essa Jd 6 elelo Jed' saxl; uos sanbslp sa D aldwaxe Jed J 12 e, p aloe el ap suep SL sadno Dap 'qb a e se Jn 651; xne saluasa Jda J z 1 a L a: lua; e senbslp sap -.uewaledluli Jd esodwo D as Uoliua Aul, il uoles aw 6 e Jqdelp a-1 a Jiw ap au 611 el el ns ljadde J uos e - e ll S Sl W np aepln 6 ne

  saeassa Jpe J s Bnul uom suolsua ap aw Jo; snos O 'saslllln a 1 uewa Ble Ji.

  ap anbluo Jl: al, aun jed sauualsaje D seauuop Joo 3 ue sli Ja AUOD luos OL sa Jlelod s Bauuop Joo sap; ll: D: arqo, j ap ele Do J a 3 ue; slp / J = o J a Q a ^ l Jap ep xneu 6 is Sal 'ú an J 114 el a J uow el awwo Uo' l UBW Gle W Jo N sa Jl Eelod saeuuop Joo D 3 p awas AI Ss al suep a Jl Iein 6 fue uop lsod el Bp a Jnsaw el auuop to Duenba J; p apnl lldwe, l ap o Jaz ne a 6 essed np: b 7 onb 16 olouo J 4: L a 6 eseqdap S el anb slpue 1 'B Jlw Bp a UÈll el sindap J a ^ lnjp el ap a Jnsaw el auuop 4 V azuenbfa J; ap uols Jn Dxa, l ap Jnale A e-E O L a ue s o D aouanbe J; el ap l ue E Je 8 e, s 6 aleplosnuls aw Joo; aun pue Jd a Duanb'a J; el (L a Jn 61;) 8 Jlw ap au 5611 el ap a Bje Je D, s all S Slw el anb sac L a Ln 61; el ap L

T 9 úZ 69 Z

  that in the event of a significant drift the sinusoidal shape of the frequency excursion will deform, therefore that the measurement of the angle O will differ from the value O t of the theoretical measurement Oth In FIG. 6, the curve represents the shape of the frequency for a small drift from the line of sight 8 (FIG. 1), and the curve 16 this pace for a large drift "r" As shown in FIG. 7, this chronological phase shift is linked to r by the fixed ratio = arc sin r 2 R A correction, by calculation, of this phase shift would require a long calculation of trigonometric function and it is possible to carry out this correction in advance by an appropriate rectification of the curvature of the slots of the discs Figure 8 a represents the disc 1 comprising a rectified slot II '; FIG. 8 b represents the disc 2 comprising a slot

  12 'whose curvature is corrected by + fi O I'; and Figure 8 c shows

  feels the disc 3 comprising a slot 13 'whose curvature is rec-

  tified of PO 'The figures 11, 12 and 13 indicate the course of the median lines of the slits of FIGS. 4 a and 5 b, the curvatures of which have not been corrected. As FIGS. 9 a and 9 b also show, these curvatures always allow the adjustment to be made in accordance with the actual measurements i fin and On Pn

  FIG. 9 c shows the cooperation of the disc 1 with the disc 3.

  According to other embodiments, not shown in the drawings, it will be possible, depending on the flight properties of the missile, to use other combinations of discs and slots, without

  that leave the field of the invention.

  As can be seen in Figures 5 and 9, the diaphragms

  my present, in addition to the opening 18 placed on the fin "r", a small central window 17, most often circular, through which

  forms the focal point of the viewfinder and its surroundings on the focal plane

  immediate In guide devices automatically returning

  the missile on the line of sight by means of the drift voltages obtained

  naked, the field of this window must not contain any disturbing irradiating element because it constitutes the only remaining opening after

  recall of the missile on the line of sight.

  In tracking devices, this window can be used to maintain the aiming on a predetermined target (on a fixed star, for example), while the diaphragm, independently brought to a second target by the positions O and fi, will be used to determine the relative position of this second target, the rest of the firmament remaining completely obscured It will therefore be necessary to receive from these two targets drift signals chronologically separated from each other, result obtained by the device of FIG. 10 in which a third disc 4, rotating at a constant speed UW 3, allows the radiation of the target 6 and that of the target 6 to pass alternately. The disk 4 may also include several alternating zones of transparency and

  occultation during a single revolution.

  To completely obscure an irradiating element 6 located

  exactly on the line of sight, the axis of rotation 8 'of the disc 4 must

  be offset by a value "e" which must be at least equal to half the diameter of this element 6, and whose angular position

  may be related to that O N of the irradiating element 6 '.

  A second exemplary embodiment of the invention provides for the possibility of guiding a second missile at a second target while the first missile regularly travels on a fixed trajectory After the first missile, protected against disturbing radiation by the diaphragm 1, 2 , 3 in position p / e, was brought on the line of sight and progresses regularly towards its target, protected by the window 17, the second missile is launched on a trajectory

  waiting side predetermined and brought, itself protected by the dia-

  phragm in position p / G, on a second line of sight on which it is maintained As soon as the first missile has reached its goal, the second is fired and the predetermined fixed drift of the second missile is eliminated; the second missile is thus brought back on the line of sight and guided towards its goal Once this second missile placed on the line of sight, it is possible to launch a third, then a fourth missile,

And so on.

  The part of the housing 25, shown in FIGS. 14 a, 14 b and 15, is a constituent element of the locating and tracking optics of the guidance device. The line in points and lines 36 represents the focal plane of this optics The missile, in the case it presents a rocket, is guided towards its goal in the usual way, the gunner making coincide with the target to bombard the line of sight 8 (figure 1) of the day vision channel of the apparatus of guidance, which will then serve as a guiding radius for the rocket The drift of the rocket in relation to the guiding radius is calculated permanently by

  the goniometer based on the irradiated thermal energy and the path

  roof is corrected accordingly by wired or wireless telecommunication When the rocket is fired from a launch pad, it

  usually has a fairly wide dispersion at the start and the appearance

  guide reel placed on the side of the launching pad therefore needs a wide image angle to grasp the rocket As soon as this is achieved and the (semi) automatic guidance of the missile comes into action, the dispersion is reduced and the device is automatically switched to a smaller image angle We therefore need two diaphragms (one for each image angle of the thermal image channel) each made up of the two slotted discs 1 and 2 already described These discs are fixed to the bottom of mounts 27 and 28, in the form of bushels (FIG. 14 a). On the external periphery of the mount 27 engages the double ball bearing 29, 30 housed in the plate 35 fixed to the housing 25 Le

  cover 37 covering the diaphragms, their bearings and their mechanisms

  drive nisms, itself also fixed to the plate 35, will play here the role of counter bearing The external portion of the part of the frame 27 overlapping the internal ball bearing 29 has the form of a

  Toothed wheel 19 Likewise, the part of the frame 28 'fixed to the peri

  external sphere of the internal ball bearing 29 has the form of a toothed wheel 19 'These two toothed wheels of the diaphragm 1, 2 to the left of FIG. 14 b are each coupled to a stepping motor 26 or 26' by a gear 31/32 or 31 '/ 32' But they are also coupled, by gears 33 or 34, to the diaphragm placed to the right of the same

  figure, that is to say its cogwheels.

  According to another embodiment, not shown, of embodiment, a drive will be used by friction plates or by belts or

  even a continuous drive by means of a motor and a tachog-

  generator for measuring the instantaneous position With a

  by stepper motor it is essential to adjust the position of

  start at e 00, and this is desirable with the other input modes

  drag For this, a determined location on the periphery of the diaphragm mount, such as the tips of teeth 19 or 19 '

  visible in Figure 14 b, will be made reflective and a photocell

  toelectric dam 20 or 20 'will be placed opposite Each time, for the angular position, one of the conditions below is met Disc 1 in = O' or 360 Disc 2 & n fn = O or 3600 Disc 3 in En = O or 360 the cell closes the barrier and a counter, not shown, is set to zero If the barrier closed earlier or later as a result of steps

  lost or slip, this error can be corrected automatically.

only in the counter.

  With star-based tracking devices, the position of fixed stars in the sky is known in advance and the position of the diaphragm / 5) / O 1, 2, 3 can be predicted accordingly With

  tracking devices for guiding missiles, we can consider

  determine, in accordance with experience, that after its departure the missile sends to the objective of the guidance device, due to its proximity,

  a disproportionately large power and that its surface will

  diante represents a fairly large image angle The radiation, falling on the focal plane through a tight network of slots 24 of the discs, is therefore enough to identify the missile and can be used to capture it by the diaphragm P / e 1, 2, 3 Each of the discs 1, 2, 3 of FIGS. 11a, 11b and 11c, respectively, is provided, in addition to the slots 11 ', 12' and 13 ', with such a tight network constituted by a plurality of slots forming a grid, formed on the periphery of the discs The slots of the grid of a disc are oriented in the same direction as the slots 12, 13 or 12 ', 13', and in the opposite direction of the slots of

the grid of the other disc.

  This orientation in reverse appears most clearly on the

  figure 12 o the two discs of a diaphragm are shown super-

  placed and o the network of slots 24 of the lower disc 3 is visible through the slot 12 'of the upper disc 2 The slots of the grid have the form of involutes and are regularly spaced from one another Their width is only a few hundredths of this spacing so that by superimposing a network of slots oriented inversely,

  a transmission of the order of magnitude of a few pros is obtained

  mille The width of the ring formed by the grid of slots is fixed so that, after gripping the missile, its capture by the diaphragms / 91, 2, 3 is ensured before the guide device has brought it too much X 5 to the center 8 of field 5 (figure 1) If this reminder is very quick, the

  grille (except the wide slots) should occupy the entire diaphragm.

  To accelerate the capture of the missile, the diaphragm 2, 3 in FIG. 12 can be brought to a so-called waiting position 21. To gain this position, the two discs 2 and 3 are made to rotate, after the modulating disc 7 is started. (figure 1) until each barrier photocell 20 and 20 '(figure 14 b) has emitted its pulse and reduced the counters to zero The two discs are then brought to their pre-programmed position, defined by supposed entry of the missile in the field In Figure 12, for example, we expect the arrival of the missile from the upper left to the upper part, the transmissive portion of the grid

  24 being 5% A central window is formed, completely transparent

  annuity 17 which, as has already been said, has no harmful effect There is also a crown 22 in which the transmissibility is 2.5 O / and, if the wide slits go so far as to penetrate the grid ring slots, two surfaces 23, located in this crown, having a transmissibility of 5% The crown 22 can be reduced depending on the accuracy of the input forecast of the missible in its opening angle so as to be 1800, for example, in the standby position, while the part of the crown in which the two diaphragm discs overlap will decrease as the missile

will approach the center point.

  In the modulator systems having two different image angles, the angle Gth remains constant while the drift r of the image, therefore the correction angle a ,, vary according to the magnification factor 8 = f 1 / f 2 objectives We must therefore calculate the new position of the diaphragm after switching from the old position and readjust the corresponding angular steps during switching As the

  shown in Figure 13a, switching from Pl to P 2 is done in addi-

  cutting or subtracting 8 times the angle / D 1 As, according to figure 13 b, the correction angle does not represent a linear function, 1 n we will have to determine a factor nl N 2 / finl C'n 2 so that, when y will be an integer, the deviation of o An 2 is as small as possible The curved line in dots and lines in Figures 13 a and 13 b corresponds to those in Figures 8 a or 4 b and indicates the slots 11 'or 12 On these curved lines, the points 6 nl and 6 N 2 are those where the image of the radiation emitter 6 is formed, according to the instantaneous focal distance. We can therefore calculate, with an accuracy of a few steps, the new position of the discs using the formulas below. Disc I: (nl N 2 nl nln 2 nl + Y / On 1 Disc 2: enl-_n 2 / Onl_-n 2 = nl -n 2 + n 1-n 2 P / Pnl = nl + (y -8) pnl Disc 3: nl N 2 + O nl N 2 nl N 2 + 'nl N 2 + // pnl n = N (y +) / nl Once the switching has been carried out, the normal diaphragm tracking calculation can be resumed with the new values (n 2 and PN 2 f N nt _ ,,, _ =

Claims (18)

  1 Method for obscuring disturbing targets in the focal plane of a missile guidance device by means of a mechanical diaphragm which only forms, on a detector placed behind the focal plane, after the missile has left, the image of the radiant energy of the image area proper and that of its immediate vicinity, energy previously modulated at a constant frequency in the focal plane, so that a drift of the missile   from the optical axis produces a sinusoidal deviation from the   medium quence, called frequency excursion A Pf, represents   both the measurement of the drift r of the missile from the optical axis, while the phase shift in time At of the passage to zero of the frequency excursion will represent the measurement of the position   angular O in the polar coordinate system, characterized-   in that a) the angular position G of the missile (6) and the excursion of frequency t f are divided into equal angular steps; b) the diaphragm used consists of at least two slotted discs (1, 2, 3) arranged one behind the other and coaxially in the center (8) of the focal plane; c) the discs (1, 2, 3) are offset so as to generate at least one zone of intersection of the slots of each disc (11 to 13 ') which can constitute a diaphragm opening (18); d) the diaphragm opening (18) is brought into coincidence with the image of the radiant energy of the missile (6) in the focal plane; e) the drift signals guiding the missile (6) are used to control the slotted discs (1, 2, 3) so that by continuing the rotation of the discs the missile is brought, as well as the diaphragm opening (18 ), in the center, no   obscured by the diaphragm, from the focal plane.   2 Method according to Claim 1, characterized in that the opening   diaphragm (18) can be moved in the image field (5) by rotation of the slotted discs (1, 2, 3) from the angle on or an minus or more the depth angle Pn (Figures 5a , 5 b and 9 a to 9 c).   3 Method according to Claims 1 and 2 characterized in that it is   applied to a tracking device.   4 Method according to Claim 3 characterized in that it consists in pointing the center, not obscured by the diaphragm, on a fixed irradiating target (6), to be determined independently, by the diaphragm opening (18), the relative position of a missile (6 ') by positions G and /, and to obtain signals from the two targets   drift chronologically separated from each other (Figure 10).   Method according to one of Claims 3 and 4, characterized in that   that the fixed irradiating target is a fixed star and in that the   rest of the firmament is completely obscured.   6 Method according to one of Claims 3, 4 or 5, characterized in that   that it consists in using, together with the two slotted discs (1, 2, 3) a third disc (4) letting pass alternately   the radiation from the two irradiating targets, the axis of which   rotation (8 ') is offset from the value e, the angular position of this eccentricity being related to the angular position t N of missile (6 ').   7 Method according to any one of the preceding claims,   characterized in that it consists in guiding towards its target a first missile (6) covered by the third disc (4) and protected against the environment by the diaphragm opening (18) by bringing it into the center not obscured , that is to say in the line of sight; at   launch in parallel, on a lateral waiting path   mined, a second missile (6 ') protected by the diaphragm (1, 2, 3) then released, and to maintain it there until the impact of the first missile on the first target; aiming at a second target, suppressing the predetermined waiting trajectory, and finally bringing the second missile into the line of sight, that is to say on the target intended for it; then to launch then in parallel a third   then a fourth missile, and so on.   8 Method according to any one of the preceding claims,   characterized in that it consists in engaging the modulator (7) and bringing, by rotation, the two slotted discs (2, 3) to a previously programmed waiting position (21) corresponding to   the planned missile entrance (Figure 12).   9 Device for implementing the method according to Claim 1   or one of the following Claims, characterized in that the   discs (1, 2, 3) have a circular shape and each have   a slot (11 to 13 ') running from their common center (8) to their peri   spheres by a different path, one of them having the shape of a sector of a circle and the other a spiral shape, the common center of the two discs having the shape of a window essentially circular (17).   Device according to Claim 9, characterized in that the increase   the radial spiral corresponds to the distance from the image center r = le, and the angular increase to the focal distance '   variation of the frequency excursion Af.   11 Device according to one of Claims 9 and 10, characterized in that   that the disc (1) with circular sector slot (11 or 11 ') is replaced by a disc (3) comprising a slot (13 or 13') inversely symmetrical to the spiral slot (12 or 12 ') (Figures 5 b and 9 b).   12 Device according to any one of the preceding claims,   characterized in that the curvature of the two slots in the focal plane is increased or decreased by a corrective factor J '(Figures 8 a to 8 c).   13 Device according to Claim 6 or one of the Claims   following, characterized in that the eccentricity e is at least   equal to half the diameter of the fixed radiation emitter.   14 Device according to any one of the preceding claims,   characterized in that the circular slotted discs are   més so as to be driven, either by toothed wheels (19, 19 ') started by a stepping motor (26 or 26') or by   a continuous drive comprising a motor and a tachogen-   erator, either by a transmission by friction plates or by belts (Figures 14 a, 14 b, 15).   15 Device according to Claim 14, characterized in that the   starting position is indexed to e = o-.   16 Device according to Claims 14 and 15, characterized in that   that a well-defined point on the periphery of the slit disc or of the corresponding tooth top (19 or 19 ') is made reflective, and in that it is arranged opposite a photoelectric cell of   dam (20 or 20 ') bringing a counter to zero (Figure 14 b).   17 Device according to any one of the preceding claims,   characterized in that the discs (1, 2, 3) are provided, in addition to the comparatively large slots (11 to 13 '), with a tight network of slots forming a grid 24, arranged in opposite directions and having the form of involutes regularly spaced and of a width corresponding to only a few hundredths of the interval separating them (Figures 11a to 11c). 18 Device according to Claim 17, characterized in that the network of grid slots (24) occupies, on the slot disc (1,   2, 3) an annular surface concentric with the latter.   19 Device according to any one of the preceding claims,   characterized in that the first slit discs (1) as well as the second slit discs (2) of at least two diaphragms (1, 2) are coupled by a toothed wheel (33 or 34), the slit discs of one of the diaphragms each being coupled to a stepping motor (26 or 26 ') by a gear (31/32 or 31' / 32 ') while the slotted discs of the other diaphragm each cooperate with a cell barrier photoelectric (20 or 20 ') (figure B).   Device according to Claim 19 or one of the Claims   previous, characterized in that the slotted discs (1, 2, 3) have different or equal diameters and are fixed on the bottom of mounts (27, 28), essentially in the form of bushels and joined together by a double bearing at balls (29, 30), held in a housing (25).