SEEKER OPTICS, SEEKER HEAD AND GUIDED MISSILE

Abstract

Seeker optics are provided for a missile seeker head, in particular a guided missile seeker head. The seeker optics contain an optical system having at least one optical element, which is aligned so as to be positioned with respect to an optical axis and is held in at least one optics frame. The optics frame contains an actively shape-variable substance by which the location of the at least one optical element in the optical system can be varied relative to the optical axis and/or by which the shape of the optical element can be adaptively varied.

Claims

1. Seeker optics for a missile seeker head, the seeker optics comprising: an optical system having at least one optical element being aligned so as to be positioned with respect to an optical axis; and at least one optics frame holding said at least one optical element, said at least one optics frame having an actively shape-variable substance by which a location of said at least one optical element in said optical system can be varied relative to the optical axis and/or by which a shape of said at least one optical element can be adaptively varied.

2. The seeker optics according to claim 1, wherein said actively shape-variable substance of said at least one optics frame contains a fiber-reinforced substance material, the fiber-reinforced substance material forming a matrix in which fibers are embedded.

3. The seeker optics according to claim 2, wherein: said fibers contain carbon fibers, glass fibers and/or basalt fibers; or said fibers are carbon fibers, glass fibers and/or basalt fibers.

4. The seeker optics according to claim 2, wherein said fiber-reinforced substance material: contains at least one material selected from the group consisting of epoxy resins, vinyl ester resins, polyurethanes, polyether ketones, and polyether ether ketones; or consists of at least one material selected from the group.

5. The seeker optics according to claim 1, wherein said actively shape-variable substance forms an actuator unit, which for an active shape variation contains at least one inverse piezoactive material, at least one electrostrictive material and/or at least one magnetostrictive material.

6. The seeker optics according to claim 1, wherein said actively shape-variable substance forms an actuator unit having inverse piezoactive materials.

7. The seeker optics according to claim 1, further comprising at least one sensor unit being adapted to measure an ambient temperature and/or to generate sensor signals characteristic of shape variations of said at least one optics frame.

8. The seeker optics according to claim 7, wherein said sensor unit contains piezoelectric crystals, piezoelectric fibers and/or at least one resistive strain gauge strip, inductive displacement sensors, inductive distance sensors, magnetoelastic sensors, capacitive differential sensors and/or fiber-optic temperature sensors as sensor elements.

9. The seeker optics according to claim 7, further comprising a control loop which is adapted for control-technological shape adaptation of said at least one optics frame by adaptation of said actively shape-variable material on a basis of the sensor signals or of at least one value or quantity derived therefrom as a command quantity.

10. The seeker optics according to claim 9, wherein said control loop is adapted to determine a quantity characteristic of the ambient temperature, a quantity characteristic of a length change and/or a quantity characteristic of a volume change of said at least one optics frame from control signals, and to use a quantity as a command quantity.

11. The seeker optics according to claim 7, further comprising a regulation loop which is adapted for regulation-technological shape adaptation of said at least one optics frame by adaptation of said actively shape-variable material on a basis of the sensor signals or of at least one value or quantity derived therefrom as a regulation quantity.

12. The seeker optics according to claim 11, wherein a derived value is values or quantities characteristic of a shape of said at least one optics frame, of a shape of segments of said at least one optics frame or of corresponding shape changes.

13. The seeker optics according to claim 1, wherein said optical system contains multistage optics, and said at least one optics frame holds said at least one optical element of at least one stage of said multistage optics.

14. The seeker optics according to claim 13, wherein said multistage optics contains two-stage optics, including a first stage which forms reflective optics, and a second stage configured as refractive optics, said actively shape-variable material of said at least one optics frame holding optical elements of said first stage.

15. The seeker optics according to claim 1, wherein: said optical system contains a mirror telescope having a primary mirror and a secondary mirror, and said at least one optics frame of said mirror telescope forms a spacer for separating said primary mirror and said secondary mirror; and said at least one optics frame is configured in such a way that a relative location of said primary mirror and said secondary mirror can be adaptively varied by said actively shape-variable material in order to compensate for thermally induced and/or acceleration-induced distance changes and/or in order to compensate for manufacturing and adjustment tolerances.

16. The seeker optics according to claim 2, wherein said fiber-reinforced substance material is a fiber-reinforced plastic material, the fiber-reinforced plastic material forming the matrix in which the fibers are embedded

17. The seeker optics according to claim 6, wherein said inverse piezoactive materials include piezoelectric crystals and/or fibers as actuator elements, which are embedded in a volume material of said at least one optics frame while being aligned according to at least one preferential direction.

18. The seeker optics according to claim 7, wherein said at least one sensor unit is at least partially embedded in a volume material of said at least one optics frame and/or applied on a surface of said at least one optics frame.

19. A seeker head, comprising: an interface for mounting on a missile and containing at least one set of seeker optics, each of said seeker optics containing: an optical system having at least one optical element being aligned so as to be positioned with respect to an optical axis; and at least one optics frame holding said at least one optical element, said at least one optics frame having an actively shape-variable substance by which a location of said at least one optical element in said optical system can be varied relative to the optical axis and/or by which a shape of said at least one optical element can be adaptively varied.

20. A missile, comprising: at least one seeker head having an interface for mounting on the missile and containing at least one set of seeker optics, each of said seeker optics containing: an optical system having at least one optical element being aligned so as to be positioned with respect to an optical axis; and at least one optics frame holding said at least one optical element, said at least one optics frame having an actively shape-variable substance by which a location of said at least one optical element in said optical system can be varied relative to the optical axis and/or by which a shape of said at least one optical element can be adaptively varied.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0053] FIG. 1 is a diagrammatic, cross-sectional view of a seeker head according to the invention;

[0054] FIG. 2 is a perspective view of a first optical stage of the seeker head with an optics frame;

[0055] FIG. 3 is a perspective view of the optics frame according to FIG. 2;

[0056] FIG. 4 is a schematic representation of a control loop for adaptive variation of the optics frame;

[0057] FIG. 5 is a schematic representation of a regulation loop for adaptive variation of the optics frame; and

[0058] FIG. 6 is an illustration of a (guided) missile with the seeker head.

DETAILED DESCRIPTION OF THE INVENTION

[0059] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:

[0060] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a cross-sectional representation of a seeker head 1 having a housing 2. At the end, the housing 2 has a viewing window 3, which is convexly curved as seen from inside the housing, for seeker optics 4 having an optical system 5, which are located inside the housing.

[0061] The seeker head 1, or the seeker optics 4, comprise for example an infrared-sensitive detector 6, i.e. a detector 6 which is sensitive to infrared radiation. In front of the detector 6 in the optical system of the seeker head, there are two-stage optics having a reflective first stage 7 and a refractive second stage 8. Merely for purposes of visual representation, the stages of the optics are respectively highlighted by an ellipse enclosing them.

[0062] The reflective first stage 7 of the two-stage optics comprises a primary mirror 9 and a secondary mirror 10, the arrangement of which corresponds to that of a mirror telescope. Infrared radiation 11 on the seeker head 1 incident from the outside through the seeker window 3 strikes the primary mirror 9, or more precisely a concavely curved mirror surface of the primary mirror 9, by which the incident infrared radiation 11 is focussed onto the secondary mirror 10. The secondary mirror 10 contains a convexly curved mirror surface, which is arranged in the beam path in such a way that the incident infrared radiation focussed by the primary mirror 9 is guided, or focussed, further onto the refractive second stage 8 of the two-stage optics.

[0063] The refractive second stage 8 contains a plurality of optical elements, inter alia prismatic optical elements and lenses, which are arranged and positioned along the optical axis O in such a way that the infrared radiation fed into the second stage 8 by the secondary mirror is imaged onto the detector 6. On the basis of the image of the infrared radiation on the detector 6, the seeker head 1 may for example identify and/or track a potentially relevant target or object, and to this extent generate data for targeted control of a missile.

[0064] The accuracy of the seeker head 1 for the identification and tracking of a target or object depends, in particular, on the imaging characteristics and imaging accuracy of the optical system 5. The imaging characteristics/imaging accuracy of the optical system 5 may in turn be crucially detrimentally influenced by external influencing factors, for example the temperature or temperature changes.

[0065] For example, the relative location of the optical elements with respect to one another or their position relative to the optical axis O and/or their shape may be varied by thermal expansion or contraction, or other external influences such as acceleration forces. Such variations may crucially degrade the imaging characteristics of the optical system 5, entailing a reduction of the accuracy of the object or target acquisition or tracking.

[0066] In order to counteract such variations in location and/or position of the optical elements and/or in shape, the optical system 5 of the seeker head 1 of FIG. 1 contains an optics frame 12 with which, in the present exemplary embodiment, in particular the primary mirror 9 and the secondary mirror 10 are held, the optics frame 12 containing an actively shape-variable substance by which at least the location, in particular position and/or alignment, of the primary and secondary mirrors 9 and 10 in the optical system 5 can be adaptively varied at least in a direction parallel to the optical axis.

[0067] In some configurations, the actively shape-variable substance may also be provided in such a way that the optical elements of the refractive second stage 8 can be adaptively varied in their location, in particular position, in, transversely and/or rotationally with respect to the optical axis, and/or in their shape. Such configurations may be implemented in a similar way to the exemplary embodiment described below, in which case adaptation of the location of the optical elements may correspondingly be applied separately for each stage of the optics or for the optics as a whole.

[0068] The optics frame 12 of the reflective first stage 7 of the optical system 5 is represented in further detail in FIGS. 2 and 3.

[0069] FIG. 2 shows a perspective representation of the optics frame 12, the optics frame 12 in the present example forming a frame or holder, which on the one hand holds the two mirrors 9, 10 and on the other hand positions the mirrors at a predetermined distance from one another, particularly in the direction of the optical axis O. To this extent and in particular, the optics frame 12 forms a spacer for the optical elements 9, 10 of the mirror telescope of the reflective first stage 7 of the optical system 5. Such spacers are also referred to as spiders in the context of mirror telescopes.

[0070] Particularly in order to compensate for length changes, for example distance changes, of the mirrors 9, 10 of the reflective first stage 7, for example caused by temperature changes, in particular by a change in the ambient temperatures or by other external effects during use of the seeker head, the optics frame 12, or the spider 12, has the aforementioned actively shape-variable substance.

[0071] In the exemplary embodiment of FIG. 3, the actively shape-variable substance contains piezoelectric crystals 13, which are embedded with a given alignment or preferential direction in the volume material of the spider 12. Although the exemplary embodiment is described with the aid of piezoelectric crystals 13, the comments below also apply similarly for other actively shape-variable substances, for example in general inverse piezoactive materials, electro- and/or magnetostrictive materials, etc., as already described above in general.

[0072] Specifically, and particularly as may be seen from FIG. 3, the piezoelectric crystals are embedded in the volume material of the spider arms 14 which are present between respective holding segments or the primary mirror 9 and the secondary mirror 10. The volume material may, for example, be a fiber-reinforced plastic material. In further configurations, piezoelectric crystals may also be present in other segments or regions of the spider 12, or of the optics frame, so that the location or position and/or shape of the optical elements can be varied in corresponding segments.

[0073] The piezoelectric crystals 13 are embedded according to the given preferential direction in such a way that the extent of the arms 14 of the spider 12 in the direction of the optical axis can be actively varied by applying an electrical voltage to the piezoelectric crystals 13. The extent of the arms 14 in the direction of the optical axis O can therefore be adaptively varied. With the adaptive variation of the extent of the material in the direction of the optical axis O, in particular the length of the arms 14 in the direction of the optical axis can be varied. With adaptation of the length of the arms 14, in particular the positions P1 and P2 of the mirrors 9, 10 and their relative location, i.e. the mutual distance d, may in particular be adjusted.

[0074] With the variation of the distance d, for example a position change of the mirrors 9, 10 caused by thermal expansion or contraction when the ambient temperature changes may be counteracted. In particular, the distance d may be adjusted by corresponding driving or regulation of the piezo crystals 13 in such a way that the mirrors 9, 10 are adjusted according to a respectively predetermined setpoint value.

[0075] Besides the piezoelectric crystals 13 aligned substantially parallel to the optical axis O as shown in the figures, in predetermined regions or segments of the optics frame 12 they may also be embedded transversely, in particular perpendicularly, with respect to the optical axis O. Furthermore, the piezoelectric crystals 13 may also be embedded outside the arms 14. The effect achievable by suitable embedding of the piezoelectric crystals is that the optics frame can be adapted in shape in such a way that the location, in particular position and/or alignment, and/or shape of the optical elements can be adjusted, i.e. adapted, parallel, transversely and/or rotationally with respect to the optical axis O.

[0076] With suitable embedding of the piezoelectric crystals and suitable materials of the optical elements, it is also suitable to achieve the effect that the shape of the optical elements can be varied. For example, the shape of the parts of the optics frame 12 which hold the optical elements may be adapted by piezoelectric crystals, laid longitudinally and/or transversely with respect to the optical axis, generating deformation forces. On the basis of the shape change of the optics frame, the shape of the optical elements, for example of the mirrors 9, 10, may in turn be varied or adapted.

[0077] It follows from this that, by corresponding application of an electrical voltage to the piezoelectric crystals 13, a position and/or shape change caused by thermal expansion or contraction of the material of the optics frame may be counteracted. In particular, changes in the distances between the optical elements, caused by temperature variations, may be compensated for. Similarly, changes in the refractive index of the surrounding medium, or other external influences which degrade the optical imaging properties of the optical system 5, for example (installation) tolerances, movement-induced shape changes (for example caused by missile movements and associated accelerations), moisture, etc., may also be compensated for.

[0078] FIG. 4 shows a schematic representation of a control loop 15 for the adaptive variation of the optics frame 12. The control loop 15 may for example be accommodated in the seeker head 1, and in particular implemented in a seeker head control.

[0079] The control loop 15 contains a control unit 16, which is connected or coupled by signal technology on the one hand to a temperature sensor 17 and on the other hand to the optics frame 12, for example to the arms 14 of the optics frame 12. In particular, the control unit 16 is coupled to the region of the optics frame 12 in which the piezoelectric crystals for forming the adaptively shape-variable properties are embedded. This region will also be referred below to as the piezo region P for brevity. In this case, the signal-technological electrical connection between the control unit 16 and the piezo region P is adapted in such a way that the control unit 16 can apply a voltage U to the piezo region P. The length of the piezoelectric crystals 13 in the piezo region P changes according to the level of the voltage U, so that a shape change, in particular a length change, is induced, particularly in the region of the arms 14 of the optics frame 12.

[0080] The control unit 16 is adapted in such a way that, as a function of the sensor signals of the temperature sensor 17 for the respectively measured ambient temperature T, abbreviated below to temperature T, it determines a voltage U which must be applied to the optics frame 12, in particular the piezo region P, so that a thermally induced expansion or contraction of the optics frame 12 can be counteracted by a corresponding length change of the piezoelectric crystals 13. To this end, the control unit 16 may for example be correspondingly programmed and, in particular on the basis of thermal expansion coefficients, determine a voltage U suitable for the respectively measured temperature T, with which the thermal contraction/expansion at the measured temperature relative to a reference temperature can be compensated for by the length change of the piezoelectric crystals. In the present exemplary embodiment, the temperature T measured by the temperature sensor 17 is used as a command quantity for the control loop. The distance d may therefore be varied by control technology, which means that, in particular, the mutual distance of the optical elements can be adaptively varied, and in particular can be adjusted within a certain scope.

[0081] In some configurations, for example according to FIG. 5, the seeker head 1 may comprise a regulation loop 18, or a regulation loop 18 may be assigned to the seeker head 1 or to the seeker optics 4.

[0082] The regulation loop 18 may, in particular, be configured for regulation-technological shape adaptation of the optics frame 12. In particular, as schematically represented in FIG. 5, the regulation loop 18 may comprise a regulation section having a regulation unit 19 and a shape sensor unit 20 for recording shape changes ΔF of the optics frame 12, in particular of the piezo region P. For example, such a sensor unit may comprise strain gauge strips or piezo elements, which are for example embedded in the material of the optics frame 12 or connected thereto, and are adapted so that length changes in or transversely with respect to the optical axis O, in general shape changes of the optics frame 12 and/or of the optical elements, can be recorded.

[0083] As an alternative or in addition, the regulation loop 18 may also be adapted, in particular programmed, so that shape changes of the optics frame 12 can be determined or established on the basis of the imaging errors of the seeker optics 4.

[0084] In the regulation section, the shape change ΔF and/or one or more quantities describing the imaging error or errors may for example be used as a regulation quantity, and according to the regulation quantity which is fed back, the regulation unit may determine a respectively suitable voltage U with which shape changes of the optics frame 12, caused by temperature changes ΔT or other external influences, may be compensated for.

[0085] As already indicated, in some exemplary embodiments, an imaging error or a quantity describing the imaging error, which may be determined for example by correspondingly implemented algorithms from image data that have been/are recorded by the seeker optics, may be used as a regulation quantity in the regulation section. Correspondingly, with the regulation section it is possible to compensate for, or eliminate, imaging errors which are caused by a shape or location/position change, for example due to temperature changes or other external influences. In particular, a regulation section allows substantially continuous, or at least iteratively adaptive, correction of location changes and/or shape changes of the optics frame, or of the optical elements, and therefore iteratively adaptive correction of imaging errors in image data of the seeker optics.

[0086] In a similar way as for the control section, at least over a certain temperature range, the regulation section allows adjustment of a predetermined setpoint distance between the optical elements held by the optics frame 12, or the adjustment of a respective setpoint shape. In particular, thermally induced degradations of the imaging accuracy, or degradations caused in another way by external influences, may be compensated for by a control loop 15 or regulation loop 18.

[0087] Particularly advantageously, the optics frame comprises a fiber-reinforced plastic material, for example a fiber-reinforced epoxy resin. Such a material allows relatively simple embedding of inverse piezoactive materials, in particular piezoelectric crystals, and/or electrostrictive materials. Materials having magnetostrictive properties may also be envisaged, so that location/position and/or shape changes may be compensated for on the basis of the magnetostrictive properties.

[0088] Lastly, FIG. 6 shows a missile 21 known per se, in particular a guided missile 21, having a seeker head 1 according to one configuration of the invention. The seeker head 1 is positioned on a nose of the guided missile 21 facing away from the propulsion side, for example on the basis of a mounting interface for mounting the seeker head 1 on the fuselage of the guided missile 21.

LIST OF REFERENCES

[0089] 1 seeker head [0090] 2 housing [0091] 3 viewing window [0092] 4 seeker optics [0093] 5 optical system [0094] 6 detector [0095] 7 reflective first stage [0096] 8 refractive second stage [0097] 9 primary mirror [0098] 10 secondary mirror [0099] 11 infrared radiation [0100] 12 optics frame [0101] 13 piezoelectric crystals [0102] 14 arm [0103] 15 control loop [0104] 16 control unit [0105] 17 temperature sensor [0106] 18 regulation loop [0107] 19 regulation unit [0108] 20 shape sensor unit [0109] 21 missile [0110] d distance [0111] ΔF shape change [0112] O optical axis [0113] Pi position [0114] P piezo region [0115] ΔT temperature change [0116] T temperature