DE102015009661B4 - Method of converting an air-to-air guided missile - Google Patents

Abstract

Method for converting an air-to-air guided missile (2) with a seeker head (1) for an air-to-ground mission, the seeker head (1) comprising one attached to a gimbal (8) and about one to the two gimbal axes vertical axis of rotation (6) rotatably mounted rotor (4), - an infrared detector (28) arranged at the intersection (29) of the two gimbal axes, - a detector cooler (30) which is thermally conductively connected to the infrared detector (28), - A radiation optics (22) non-rotatably connected to the rotor (4), and - an optical modulator (26) which is set up to guide a beam path of the radiation optics (22) onto the infrared detector (28), wherein for converting - the infrared detector (28) is replaced by a 4-quadrant detector (42) which is attached to the gimbal (8), with the 4-quadrant detector (42) having a signal preamplifier (51 ) is downstream and the 4-quadrant detector (42) and the signal preamplifier (5 1) are designed as a structural unit, and- the detector cooler (30) is replaced by a signal post-amplifier (46) which is provided with at least one signal connection (44) to the 4-quadrant detector (42),- the optical modulator (26) is replaced by a relay optics (38) connected in a rotationally fixed manner to the gimbal (28) and comprising a rod lens (40), the rod lens (40) being set up to direct a beam path of the beam optics (22) onto the 4-quadrant detector (42), the relay optics (38) and the 4-quadrant detector (42) being fixed in place in a sleeve (49) of the gimbal (8).

Description

Two technologies are generally available for the stabilization and target tracking of a seeker head in a passive infrared guided air-to-air missile (LFK=guided missile). In a first system, the LFK has a double frame in which a target acquisition unit is suspended so that it can pivot and yaw with respect to the LFK. In a second rotor-based system, a beam optic is attached to a rotatably mounted, gimballed rotor (e.g. "Sidewinder"). The rotor has a magnetic moment aligned perpendicularly to the axis of rotation, so that it can be set in rotation via drive coils on the one hand, and its axis of rotation can be tracked in the direction of the detected target on the other hand by means of alignment coils.

In general, the rotor is intended to stabilize the optical axis of the target acquisition and to be able to track the target independently of the LFK. The axis of rotation of the rotor is therefore ideally always aligned in the direction of the target, especially at the beginning of the flight when the LFK should not steer itself due to the proximity to the platform carrying it, e.g. an airplane or a helicopter. The LFK is then tracked according to the target orientation of the rotor.

In the original rotor-based system, the detector is pivotally suspended in the gimbal center, but unlike the ray optics, it does not rotate. The detector is usually designed to only provide information about the total incident IR radiation power. An optical modulator placed in the image plane of the beam optics ensures that the IR radiation power is greatest when an incident thermal beam emitted by a target is parallel to the optical axis. The modulator can be part of the rotating beam optics and in this respect rotate with the rotor or also be connected free of rotation to the cardanic suspension of the rotor or beam optics.

Which system is ultimately actually implemented in an LFK depends, among other things, on the dimensions of the LFK and in particular on the installation space available in its search head, but also on the justifiable tax expenditure. While the suspension of a unit for target detection is more complex to track in terms of control technology, a rotor-based system usually has a significantly restricted installation space for the beam optics and the detector.

A rotor-based system for target tracking usually looks for a punctiform heat source as a target, which is imaged onto a cooled infrared detector rigidly fixed in the LFK via the rotor-stabilized radiation optics. However, target acquisition via such a hot spot is quite easy to deceive with today's means, e.g. by so-called "IR decoys" in the form of a large number of flare-like sources of interference, which a missile to be identified as a target emits for its safety. A system with a double frame has the advantage that a real imaging detection can be integrated there, which can detect such sources of interference much better by means of image analysis, for example via movement vectors of the heat sources. However, due to the limited space, a rotor-based system can only be upgraded to a limited extent with such electronics for detecting IR decoys. As a result, rotor-based, passive IR-guided air-to-air LFKs, which have been established on the market for a long time and are used by many armed forces, are becoming increasingly technically obsolete.

A two-frame based seeker system is from U.S. 7,183,966 B1 famous. The system shown there has a SAL pulse detector arranged directly behind a dome, a detector in combination with an antenna for receiving microwave energy and a focal plane array, which can be a silicon quadrant detector, in Combination with a Cassegrain optics.

The invention is therefore based on the object of finding a new possible application for a rotor-based air-to-air LFK with heat-seeking IR target detection with as few modifications as possible and, if necessary, converting it in such a way that it is suitably set up for the newly intended use.

This object is achieved according to the invention by a method for converting an air-to-air guided missile having the features of independent claim 1 and by an air-to-surface guided missile having the features of claim 5 produced by means of the method are the subject of the dependent claims.

The invention is based on an air-to-air LFK with a seeker head, which has a rotor attached to a gimbal and rotatably mounted about an axis of rotation perpendicular to the two gimbal axes, an IR detector arranged at the intersection of the two gimbal axes, an IR detector connected to the rotor comprises rotationally fixed beam optics and an optical modulator, wherein the modulator is set up to a beam path of the beam optics on the infra lead red detector. According to the invention, a method for converting the air-to-air LFK for air-to-ground use is proposed, the optical modulator being replaced by relay optics which are non-rotatably connected to the gimbal and comprise a rod lens, and the IR detector replaced by a 4-quadrant detector attached to the gimbal. The rod lens of the relay optics is therefore connected to the cardanic suspension in a rotation-free manner. However, it would also be possible to mount the rod lens directly in the rotor housing so that it rotates with the rotor.

The infrared detector of the air-to-air LFK can be stationary or pivotable and yawing with the cardanic suspension. The replacing 4-quadrant detector is arranged in particular in the inner frame of the cardanic suspension and can thus be pivoted and yawed with it. The optical modulator of the air-air LFK can be designed as a refractive modulator and is designed in such a way that radiation impinging on its front side is imaged onto the IR detector with as little loss as possible. As a result, the intensity detected by the detector is higher the more the radiation optics are aligned in the direction of a heat source emitting in the spectral range of the IR detector. For this purpose, the optical modulator is usually arranged in the focal plane of the beam optics.

The rotor preferably has a magnetic moment perpendicular to the axis of rotation. As a result, the rotor can be set in rotation by means of magnetic drive coils suitably arranged in the seeker head. During operation of the LFK, the rotation can stabilize the optical axis of the beam optics, which are non-rotatably connected to the rotor. By means of magnetic precession coils suitably arranged in the seeker head, the rotor can be aligned in the direction of the target in air-to-air LFK using an output signal from the IR detector. Due to the propagation of an incident beam path by the optical modulator rotating with the rotor, the output signal has a corresponding modulation with the rotation frequency of the rotor if the rotation axis is not aligned in the direction of the IR source and thus the target.

For an air-to-ground mission, the optical modulator is now replaced with relay optics having a rod lens, and the IR detector is replaced with a 4-quadrant detector. The use of relay optics allows the focal plane of the beam path to be placed directly on the 4-quadrant detector. The rod lens of the relay optics preferably has the highest possible refractive index with sufficient transparency in a desired spectral range. Advantageously, the entry surface of the rod lens can be ground in a concave manner in order to allow focusing that is as compact as possible. The rod lens can be made of a transparent aluminum ceramic, e.g. IG6. Due to the high refractive index, this allows the rod lens to have a cylindrical shape. A concave grinding can thus be omitted. Due to the material properties of IG6, it is preferable to place the rod lens in a protective mount.

The invention is initially based on the finding that a rotor-based LFK with a heat-seeking IR target detection in air-to-air use by IR decoys in the form of a variety of flare-like sources of interference, which a missile to be identified as a target emits for its safety , is very easy to disrupt. In order to continue to be suitable for modern air combat, an LFK with heat-seeking IR target acquisition should therefore preferably be set up to identify such IR decoys as reliably as possible and to neglect them during target acquisition. This often requires complex data processing in the form of time-resolved image analysis in order to be able to distinguish the IR decoys from the actual target - usually an airplane or a helicopter - based on the movements of the heat sources in the field of view of the viewfinder by means of a comparison with predefined movement patterns.

In order to retrofit an already existing LFK concept for such data processing, additional electronic components for the additional calculations as well as an additional physical memory for the information to be entered in advance for the comparison (such as movement patterns) would have to be provided in the LFK. On the other hand, in many existing LFK systems, the IR detector in the seeker head would not have sufficient optical resolution, since often only the total power of the incident IR beam hitting the detector is registered. Accordingly, another detection unit would also have to be installed. In a rotor-based LFK, however, there is not enough space in the seeker head for such additional components, which is why electronic retrofitting is only possible with considerable development effort, if at all.

In order to expand the installation space, the suspension of the beam optics in the rotor, which guides incident IR light to an optionally adapted detector, could therefore be exchanged for a rotor-free suspension. In addition, such a suspension should preferably have a device for stabilizing the optical axis of the beam optics, since the stabilization due to the gyroscopic moment of the rotor is eliminated would. However, this would require a completely new conception of the seeker head.

The invention now surprisingly recognizes that the inconveniences mentioned can be circumvented during conversion if a rotor-based air-to-air LFK with heat-seeking IR target detection is converted for air-to-ground use. In this case, the target detection is preferably designed to track a target marked with a laser. In this case, the marking can be carried out, for example, from the carrier platform of the LFK—usually an airplane or a helicopter. Such laser-assisted target acquisition in air-to-air combat is prohibited for strategic reasons, since permanent visual contact with the enemy flying object, which is necessary for target marking, should be avoided (so-called “dogfight situation”) in order not to become an easy target yourself. For this reason, so-called "Fire & Forget" solutions are largely preferred in air combat, so that converting the LFK mentioned for laser-assisted target detection would not bring any real applicability there. The risk of offering a target yourself is only significantly lower in an air-to-ground mission of the LFK, especially at higher altitudes (from approx. 2000 meters).

By converting an air-to-air LFK for laser-assisted air-to-ground use, a system is available which, compared to commonly used air-to-ground systems, such as gliding bombs, has the advantage of a significantly lower risk due to the active target marking for collateral damage. Due to the semi-active target acquisition by means of laser marking of the target - instead of an IR-based target acquisition - the use is not only limited to targets that emit sufficient heat, but can also, for example, target protected and/or appropriately camouflaged targets such as bunkers. Since an existing LFK system is converted for this purpose, the corresponding mechanical holding devices on the carrier platform and the electronic interfaces for controlling the LFK can continue to be used without additional adjustments, which means that development effort and thus production costs can be saved. In addition, due to the minor adjustments, the new system can be available at short notice.

Preferably, an air-to-air guided missile is retrofitted with an infrared detector configured as an IR point detector, the infrared point detector being replaced by a 4-quadrant detector which is attached to the gimbal. In this context, an IR point detector is understood to mean an IR detector which, without itself supplying further spatial resolution via an incident IR beam, only detects the power of the incident IR beam. Many air-to-air LFKs with a rotor-based seeker, which are currently still listed in the contingents of various armed forces, have such an IR point detector in the seeker head.

However, the target acquisition and target tracking using an IR point detector is particularly easy to deceive with modern means in air combat, for example using so-called "IR decoys" in the form of flare-like sources of interference. Since the IR point detector does not permit any spatial resolution of the detected objects, the target detection cannot sufficiently distinguish the IR decoys from the originally intended air target - usually an airplane or a helicopter. Since there is not enough installation space in a rotor-based seeker head to electronically improve target acquisition by detecting or distinguishing between IR decoys, the proposed method for rotor-based air-to-air LFK with an IR point detector is particularly advantageous.

An air-to-air LFK is expediently retrofitted with radiation optics comprising Cassegrain optics, the Cassegrain optics comprising a primary mirror and a curved secondary mirror, in particular perpendicular to the axis of rotation or curved towards the axis of rotation and/or inclined to the axis of rotation, and wherein the curved and/or inclined secondary mirror is replaced by a secondary mirror that is flat or perpendicular to the axis of rotation. In other words, a curved secondary mirror is replaced by a planar secondary mirror. An inclined secondary mirror is replaced by a secondary mirror that is perpendicular to the axis of rotation. A curved and tilted secondary mirror is replaced by a flat secondary mirror or one that is perpendicular to the axis of rotation. The primary or secondary mirror is understood here to be that mirror which reflects an incident beam in the beam path as the first or second mirror in the direction of the 4-quadrant detector. In another variant, the Cassegrain optics include a secondary mirror aligned perpendicular to the axis of rotation.

If the primary and/or secondary mirror is designed as a rear surface mirror, so that the beam path penetrates an optical glass upon reflection at the relevant mirror, the respective primary and/or secondary mirror designed as a rear surface mirror can preferably also be replaced. A primary or secondary mirror designed as a rear surface mirror is due to the dispersion of the optical glass, through which the beam path is guided to the reflecting rear surface, to the spectral range of the one to be detected Adjust light in order to be able to lead a sufficient amount of incident light in the beam path to the detector in the frequency range to be detected. An IR detector set up for thermal target detection, as is widely used in an air-to-air LFK, often detects IR light in a spectral range with a wavelength greater than 2 μm for target detection.

If the air-to-air LFK is converted for laser-assisted air-to-ground use, the dispersive elements of the radiation optics should preferably be matched to the wavelength of the laser used for target marking. A large number of lasers commonly used for target marking have a wavelength shorter than 1.5 μm. Due to the high spectral power density, an Nd:YAG laser is often used, for example, whose emission center is at 1064 nm, with further emissions taking place in the range from 1047 nm to 1079 nm. Therefore, dispersive elements of the radiation optics are preferably to be adapted to a corresponding change in the spectrum of the light to be detected.

An air-to-air LFK is advantageously retrofitted with a radiation dome that shields the radiation optics of the seeker head, with the radiation dome being replaced by a filter dome. The radiation dome shields the radiation optics of the seeker head in the air-to-air LFK from the outside world. In the area of the radiation to be detected for target detection, which is often detected in a spectral range with wavelengths greater than 2 μm, the radiation dome has the highest possible transmission. In this case, the radiation dome is often designed as spherical glass, the center of the sphere preferably being selected at the intersection of the gimbal axes.

Due to the dispersion of the radiation dome, when there is a change in the spectral range of the light to be detected for target detection, it should preferably be replaced in such a way that the beam path undergoes as few changes as possible. In order to increase the sensitivity of target detection and target tracking, the radiation dome is replaced by an optical material which, in addition to the desired dispersion properties mentioned above, has suitable mechanical properties for the beam path in order to meet the special requirements in terms of strength and temperature resistance of a missile flying at up to twice the speed of sound suffice. In addition, the radiation dome is preferably also filtered in such a way that there is only significant transmission in a narrow spectral band, for example 200 nm, preferably 100 nm around the wavelength of the laser to be used for target marking. The filtering can be actively applied to the filter dome. The filter dome is preferably designed as a spherical glass, the center of the sphere preferably being selected at the intersection of the gimbal axes.

In addition or as an alternative, other optical elements are also advantageously filtered. Since the beam optics rotate with the rotor during operation of the seeker head, high demands must be placed on the uniformity of the optically effective surfaces when filtering the components of the beam optics in order to avoid unwanted modulation of the incident light. It is therefore preferable to carry out filtering on non-rotating elements. This can be done - in addition to or as an alternative to the filter dome - on the rod lens of the relay optics itself or between the relay optics and the 4-quadrant detector or on this itself. Preferably, a narrow-band optical filter can be provided and set up in the area of the relay optics, which is appreciably transparent only in a comparatively narrow spectral range around the wavelength of the laser to be used for target marking. Spectral ranges outside of this band can preferably be filtered with an additional filter glass, which is arranged in front of the relay optics. For example, a carrier lens of the guided missile is designed as filter glass.

According to the invention, the air-to-air LFK having a detector cooler, which is thermally conductively connected to the IR detector, is converted by replacing the detector cooler with a signal post-amplifier, which is provided with at least one signal connection to the 4-quadrant detector or to put it another way: Instead of the detector cooler that is no longer required, a signal post-amplifier for the 4-quadrant detector is arranged in the space that has been freed up there. According to the invention, the 4-quadrant detector is also followed by a signal pre-amplifier, which amplifies the signals of the 4-quadrant detector in such a way that they can be fed to the signal post-amplifier via the at least one signal connection. According to the invention, the 4-quadrant detector and the signal preamplifier are designed as a structural unit in order to be able to optimally utilize the available structural space. The 4-quadrant detector can consequently be connected indirectly via the signal pre-amplifier or directly to the signal post-amplifier via the at least one signal connection. In the field of military target detection, an IR detector often requires cooling in order to have a sufficiently high sensitivity. For this purpose, a corresponding detector cooler is arranged in many existing systems, mostly with respect to the beam path behind the detector, which has a thermally conductive Ver bond is connected to the IR detector. The detector cooler is provided and set up to keep the IR detector in a prescribed operational temperature range via the thermally conductive connection during operation of the LFK.

For the wavelengths of most lasers commonly used for target marking, the 4-quadrant detector that replaces the IR detector does not require cooling. In this case, the detector cooler can be omitted, freeing up additional installation space in the area behind the detector. A signal post-amplifier can now be arranged in this installation space and provided with at least one signal connection to the 4-quadrant detector, the signal post-amplifier being set up to output an electronic signal from the 4-quadrant detector during operation of the LFK , to reinforce. The signal post-amplifier preferably forwards this amplified signal to evaluation and/or target tracking electronics. The advantage of such a procedure is that, for reasons of space, the evaluation or target tracking electronics are arranged offset further to the rear of the LFK. In this case, post-amplification in the case of very weak signal currents can prevent signal errors during transmission from the 4-quadrant detector or from the signal preamplifier to the electronics mentioned. The post-amplifier can preferably include a pulse amplifier whose gain can be switched. This allows the signal dynamic range to be increased.

The object mentioned at the outset is also achieved according to the invention by an air-to-ground LFK with a seeker head according to the features of patent claim 5, which was produced at least by a method for converting an air-to-air guided missile according to claim 1. The seeker head comprises a rotor attached to a gimbal and rotatably mounted about an axis of rotation perpendicular to the two gimbal axes, a 4-quadrant detector attached to the gimbal, a beam optics non-rotatably connected to the rotor, and a non-rotatable to the gimbal connected relay optics comprising a rod lens and arranged to direct an optical path onto the 4-quadrant detector. The advantages mentioned for the method for converting an air-to-air LFK for air-to-ground use and for the further developments of the method can be transferred analogously to the air-to-ground LFK. The 4-quadrant detector is arranged with the gimbal so that it can be swiveled and yawd, but it could also be arranged in a fixed position.

The radiation optics expediently have Cassegrain optics, which include a primary mirror and a secondary mirror. The beam path is such that an incident beam from outside is first reflected at the primary mirror and then at the secondary mirror and is guided to the 4-quadrant detector by means of the relay optics. The primary mirror is preferably designed as a parabolic mirror. The use of Cassegrain optics makes it possible, with a very compact design, to bundle a broadly angled incident beam onto a comparatively small area, and is therefore particularly suitable for guiding the beam path to the relay optics. In this case, the relay optics are preferably introduced into a center cut-out of the primary mirror.

It proves to be further advantageous if the Cassegrain optics has a carrier lens to which a fastening device is attached, the carrier lens being connected to the rotor in a rotationally fixed manner, and the secondary mirror being fastened to the fastening device. The use of a carrier lens makes it possible to focus the beam path onto the relay optics, particularly over a particularly short optical path, so that the distance between the primary mirror and the secondary mirror can be effectively shortened as a result. As a result, the search head can be constructed in a particularly compact manner. The carrier lens is preferably connected to the rotor at its outer edge in a rotationally fixed manner, and the fastening device is preferably attached in the region of the center of the carrier lens. The secondary mirror is thus suspended in such a way that no further carriers are required for its attachment, which would cross the beam path. The fastening device is not covered by the beam path, but is located in the area of the center cut-out of the primary mirror, in which the relay optics are installed.

• 1 in einer Querschnittdarstellung einen Luft-Luft-LFK mit einem rotorbasierten IR-Suchkopf,
• 2 in einer Querschnittdarstellung den zum Luft-Boden-Einsatz umgerüsteten LFK nach 1, und
• 3 in einer Querschnittdarstellung eine Detailansicht der Relais-Optik und des 4-Quadranten-Detektors im LFK nach 2.

An embodiment of the invention is explained in more detail below with reference to a drawing. Each shows schematically:

• 1 in a cross-sectional view, an air-to-air LFK with a rotor-based IR seeker head,
• 2 in a cross-sectional representation of the LFK converted for air-to-ground use 1 , and
• 3 shows a detailed view of the relay optics and the 4-quadrant detector in the LFK in a cross-sectional view 2 .

Corresponding objects are provided with the same reference symbols in all figures.

In 1 is a schematic cross-sectional representation of a seeker head 1 of an air-to-air LFK 2 shown. The LFK 2 is set up for air-to-air use. In the seeker head 1 , a rotor 4 is suspended on a gimbal 8 so that it can rotate about an axis of rotation 6 . The rotor 4 has a magnetic moment perpendicular to the axis of rotation 6 . A Cassegrain optic 10 is connected in a rotationally fixed manner to the rotor 4 and comprises a parabolic primary mirror 12 applied directly to the rotor 4 and a secondary mirror 14 . In this case, the secondary mirror 14 is fastened to a fastening device 16 which is integrated in the center of a carrier lens 18 . The carrier lens 18 is in turn held at its outer edge by a housing 20 which is attached to the rotor 4 in such a way that the primary mirror 12 surrounds the connection of the housing 20 to the rotor 4 . The Cassegrain optics 10 and the carrier lens 18 together form the radiation optics 22. The seeker head 1 is shielded from the outside by a radiation dome 24, which is formed by a spherical glass that is transparent in an IR spectral range.

A beam incident from the outside on the beam dome 24 is first reflected at the primary mirror 12 and then at the secondary mirror 14 and then focused by the carrier lens 18 onto an optical modulator 26 . In this case, the optical modulator 26 is set up to guide incident radiation with as little loss as possible to an IR detector 28 arranged behind it and to prevent an undesired defocusing of the beam as far as possible. The IR detector 28 arranged at the point of intersection 29 of the gimbal axes is cooled to the operating temperature by a detector cooler 30 which is thermally conductively connected to the IR detector 28 .

The seeker head 1 has a frame 32 in which a plurality of magnetic drive coils 34 and a magnetic precession coil 36 are arranged. During operation of the LFK 2, the drive coils 34 cause the rotor 4 to rotate about the axis of rotation 6 via its magnetic moment. For target detection, a beam emitted by a target in the spectral range of the IR detector 28 is now transmitted via the beam optics 22 and the optical modulator 26 out to the IR detector 28, and detected there as radiant power. The output signal of the IR detector 28 is forwarded to an electronic system, not shown in detail. If the optical axis of the radiation optics 22 or the axis of rotation 6 of the rotor 4 is not aligned exactly in the direction of the target, the incident IR radiation is modulated by the co-rotating optical modulator 26, which is reflected in the output signal of the IR detector 28 as a modulation with the Rotational frequency of the rotor 4 is noticeable. Through this modulation of the output signal, the electronics can determine correction values with which the precession coil 36 is to be controlled, so that the axis of rotation 6 or the optical axis is aligned in the direction of the target. The rotational movement of the rotor 4 stabilizes the optical axis against vibrations and other movements of the air-to-air LFK 2.

To steer the air-to-air LFK 2 in the direction of the target, rudders or engines (not shown in detail) are controlled depending on the output signal of the IR detector 28 in such a way that the longitudinal axis of the air-to-air LFK 2 is aligned in the target direction by the precession coil 36 and by the rotation of the rotor 4 stabilized axis of rotation 6, which coincides with the optical axis of the optical beam 22, is tracked.

In 2 is a schematic cross-sectional view of an LFK 2a 1 shown, which was converted for an air-to-ground mission. The optical modulator 26 is replaced by a relay optics 38, which is formed here in particular by a rod lens 40. The exchanged relay optics 38 is presently attached to the inner frame of the gimbal 8 and is therefore not rotatable. However, it can also be designed to be rotatable with the rotor 4 as part of the radiation optics 22 . The 4-quadrant detector 42 , which replaces the IR detector 28 , is arranged behind the rod lens 40 . A signal preamplifier 51 is located in the immediate spatial vicinity of the 4-quadrant detector 42. The 4-quadrant detector and the signal preamplifier 51 form a compact structural unit which is fastened to the inner frame of the cardanic suspension 8. The signal pre-amplifier 51 amplifies the signals of the 4-quadrant detector 42 in such a way that they can be routed through the gimbal 8 via a signal connection 44 and fed to a signal post-amplifier 46 with variable amplification for post-amplification. The signal post-amplifier is arranged in the installation space freed up by the elimination of the detector cooler 30 .

When converting the LFK after 1 for air-to-ground use, all dispersive elements must be replaced due to the changed spectral range of the laser for target acquisition. This relates in particular to the carrier lens 18 if this is filtered for the IR range. However, there are also variants without filters, in which case the carrier lens 18 is transparent over a wide band. The radiation dome 24 is replaced by a spherical filter dome 48 . The filter dome 48 can be filtered in such a way that the lowest possible radiation power from spectral ranges away from the laser used for the target marking can pass through. However, this is technically complex and expensive, so that this can also be dispensed with.

For the air-to-ground mission, a target is now marked with a laser of a defined wavelength from the aircraft carrying the LFK 2a. The LFK 2a is then released and, for the safety of the aircraft, operated without steering until shortly after take-off. However, in order not to lose sight of the target, the optical axis in the seeker head 1 is already aligned with the target and stabilized by the rotation of the rotor 4 . The longitudinal axis of the LFK 2a is then tracked to the optical axis by the steering - via rudders or corresponding engines. The signals from the 4-quadrant detector 42, which provide information about the deviation of the optical axis from the direction of the target, can be used directly by evaluation electronics, not shown, to control the rudders or engines. Target tracking using a 4-quadrant detector is known to those skilled in the art and will not be explained in more detail here.

For safety and to avoid deceptive and interfering signals, an irradiation pattern can be specified when marking the target, which is stored in the evaluation electronics of the LFK 2a for comparison. If the 4-quadrant detector 42 detects a beam in the spectrum of the laser used for target marking that does not have the intensity variations specified in the irradiation pattern - e.g. short, time-defined sequences of full power and dead times - the evaluation electronics can use such a signal as a Discard target acquisition irrelevant, which increases security against deception maneuvers, but also against collateral damage.

In 3 1 is a detailed view of the relay optics 38 and the 4-quadrant detector 42 in the LFK 2a in a cross-sectional representation 2 shown. According to the invention, the relay optics 38 and the 4-quadrant detector 42 are stationary in a sleeve 49 in the cardanic suspension 8 . The rotor 4 is mounted in the sleeve 49 so that it can rotate about the rod lens 40 via ball bearings 50 .

Reference List

1

seeker head

2

air to air LFK

2a

LFK converted for air-to-ground use

4

rotor

6

axis of rotation

8th

gimbal suspension

10

Cassegrain optics

12

primary mirror

14

secondary mirror

16

fastening device

18

carrier lens

20

Housing

22

ray optics

24

radiation dome

26

optical modulator

28

IR detector

29

Intersection of the gimbal axes

30

detector cooler

32

frame

34

drive coil

36

precession coil

38

relay optics

40

rod lens

42

4 quadrant detector

44

signal connection

46

signal post-amplifier

48

filter dome

49

sleeve

50

ball-bearing

51

signal preamp

Claims (7)

Method for converting an air-to-air guided missile (2) with a seeker head (1) for an air-to-ground mission, the seeker head (1) comprising - one attached to a gimbal (8) and about one to the two gimbal axes vertical axis of rotation (6) rotatably mounted rotor (4), - an infrared detector (28) arranged at the intersection (29) of the two gimbal axes, - a detector cooler (30) which is thermally conductively connected to the infrared detector (28), - a radiation optics (22) non-rotatably connected to the rotor (4), and - an optical modulator (26) which is set up to guide a beam path of the radiation optics (22) onto the infrared detector (28), wherein for converting - the infrared detector (28) is replaced by a 4-quadrant detector (42) which is attached to the gimbal (8), with the 4-quadrant detector (42) having a signal preamplifier (51 ) is downstream and the 4-quadrant detector (42) and the signal preamplifier ker (51) are designed as a structural unit, and - the detector cooler (30) is replaced by a signal post-amplifier (46), which is provided with at least one signal connection (44) to the 4-quadrant detector (42), - the optical modulator (26) by a non-rotatable gimbal Suspension (28) connected relay optics (38) is replaced, which includes a rod lens (40), wherein the rod lens (40) is adapted to a beam path of the beam optics (22) on the 4-quadrant detector (42). lead, wherein the relay optics (38) and the 4-quadrant detector (42) are fixed in a sleeve (49) of the gimbal (8). procedure after claim 1 , whereby the infrared detector (28), designed as an infrared point detector, is replaced by the 4-quadrant detector (42), which is attached to the cardanic suspension (8), for the conversion. procedure after claim 1 or claim 2 , wherein the air-to-air guided missile (2) has a Cassegrain optic (10) comprising radiation optics (22), the Cassegrain optics (10) having a primary mirror (12) and a curved and/or inclined to the axis of rotation (6). Secondary mirror comprises, and for the conversion of the curved and / or to the axis of rotation (6) inclined secondary mirror is replaced by a flat and / or perpendicular to the axis of rotation (6) standing secondary mirror (14). Method according to one of the preceding claims, wherein the air-to-air guided missile (2) has a radiation dome (24) shielding the radiation optics (22) of the seeker head (1) and the radiation dome (24) is replaced by a filter dome (48) for retrofitting . Air-to-surface guided missile (2a), produced by converting an air-to-air guided missile (2) using a method according to one of Claims 1 - 4 , with a seeker head (1), this comprising - a rotor (4) fastened to a cardanic suspension (8) and rotatably mounted about an axis of rotation (6) perpendicular to the two cardanic axes), - a 4th - Quadrant detector (42), wherein the 4-quadrant detector (42) is followed by a signal preamplifier (51) and the 4-quadrant detector (42) and the signal preamplifier (51) are designed as a structural unit , and wherein the 4-quadrant detector (42) is connected to a signal post-amplifier (46) via at least one signal connection (44), - beam optics (22) non-rotatably connected to the rotor (4), and - one non-rotatable with the gimbal (8) connected relay optics (38), which comprises a rod lens (40) which is adapted to lead a beam path of the radiation optics (22) on the 4-quadrant detector (42), the relay -Optics (38) and the 4-quadrant detector (42) stationary in a sleeve (49) of the ka rdanic suspension (8) are attached. Air-to-ground missile (2a) after claim 5 , wherein the radiation optics (22) comprises a Cassegrain optics (10) comprising a primary mirror (12) and a secondary mirror (14). Air-to-ground missile (2a) after claim 6 , wherein the Cassegrain optics (10) has a carrier lens (18) to which a fastening device (16) is attached, wherein the carrier lens (18) is non-rotatably connected to the rotor (4), and wherein the secondary mirror (14) on the fastening device (16) is attached.

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