GB2146450A

GB2146450A - Optical-mechanical scanning system having periodic beam switch

Info

Publication number: GB2146450A
Application number: GB08421213A
Authority: GB
Inventors: Siegfried Roth; Arnold Stangl
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: Airbus Defence and Space GmbH
Priority date: 1983-08-24
Filing date: 1984-08-21
Publication date: 1985-04-17
Also published as: GB2146450B; DE3330495C2; FR2551194A1; DE3330495A1; GB8421213D0

Abstract

The device has two optical systems, preferably an observation apparatus 2 for target observation and possibly target tracking and a guidance apparatus 3 for transmitting guidance signals to the missile, the two optical systems being combined in a guidance emplacement or station. Both optical systems 2,3 have a common optical scanning and representation system 4, 5,6, for the line-shaped scanning of the common field of vision in elevation and azimuth. The scanning and representation system has a periodically-controlled beam switch, preferably provided by a polygonal wheel 11 having successive edge slopes 13a, 13b inclined alternately opposingly towards the radius direction 14. The beam switch mirrors or images the two optical systems linewise alternately into the common scanning and representation system 4,5,6. <IMAGE>

Description

SPECIFICATION Device for guiding a missile into a target This invention relates to a device for guiding a missile into a target having two optical systems, preferably an observation apparatus for target observation and possibly target tracking and a guidance apparatus for transmitting guidance signals to the missile, in which the two optical systems are combined in a guidance station or emplacement.

Such devices for guiding a missile into a target have, in the guidance station or emplacement, as observation apparatus, for example, a directive periscope with which a gunner aims at the target and holds it in the line of sight by following it with the periscope. The missile carries on its tail a pyrotechnical flare, flare composition, or the like which radiates in the optical and in the infra-red range. The infra-red radiation of the flare or tracer composition is perceived in the guidance emplacement by a goniometer which develops guidance signals from the displacement of the missile from the line of sight of the periscope. These guidance signals are transmitted to the missile in order to guide this onto the line of sight of the periscope and to hold it on this until the target is hit.

In order to permit the use of such devices also at night, it is known to use, in the guidance emplacement, additional image intensifiers orthermal-image apparatus, as observation apparatus. Likewise proposals have been made to use automatic targettracking apparatuses which operate in the infra-red range, i.e. so-called IR-trackers. The guidance signals for the control of the missile can be transmitted from the guidance emplacement to the missile in a variety of ways. Known 'inter alia' are laser apparatus which radiate a light signal in which the actual guidance signal is coded.

The problem underlying the invention is to provide a simple construction for a device having two optical systems.

In accordance with the invention, this problem is solved by providing that both optical systems have a common optical scanning and respresentation system for line-form scanning of the common field of vision in elevation and azimuth, and that the scanning and representation system has a periodicallycontrolled beam switch which mirrors or images the two optical systems linewise alternately into the scanning and representation or display system.

In accordance with the arrangement of the invention, therefore, two optical systems are used, preferably a thermal-image apparatus for the target observation and possibly target tracking and a laser transmitter for transmitting the guidance signals to the missile, which both work in accordance with the scanning principle. A common optical scanning and representation or display system for the line-form scanning of the common field of vision in elevation and azimuth is provided for both optical systems. By means of the periodically-controlled beam switch, preferably a rotating polygonal wheel with alternately oppositely-inclined roof slopes along the periphery, the two apparatuses are alternately mirrored or imaged into the representation or display system.In the instance of a thermal-image apparatus as observation apparatus and of a laser transmitter as guidance apparatus, initially a line of the common field of vision is scanned by the thermalimage apparatus; then the laser transmitter is mirrored or imaged into the common scanning and representation system and sweeps over the same line of the common field of vision. By switch-over of the scanning system, for example by adjustment of an elevation scanning mirror, then the next line of the common field of vision is scanned by both apparatuses. This procedure is repeated successivley, until the entire field of vision of both apparatuses is completely scanned. This procedure then proceeds cyclically.

The expenditure for the optical system of the device is considerably less in comparison with known devices, since a common scanning and representation system is used for both optical systems. Thus, also the weight and the size of the entire guidance station or emplacement can be reduced. The periodically controlled beam switch, moreover, prevents the two optical systems from mutually interfering with one another. Because of the alternate cyclic scanning of the common field of vision it is, for example, impossible for backscattered laser light to be received by the thermalimage apparatus, so that a swamping or halation of the light, received by the thermal-image apparatus, by the laser transmitter is avoided. Such a decoupling of thermal-image apparatus and laser transmitter is particularly important because the wave length ranges of both apparatuses are approximately the same.The thermal-image apparatus is sensitive to light of the wave lengths between 8 to 12 Fm, whilst the laser light has a wave length of 10.06 clam.

The scanning and representation or display system which is common to both systems gives, additionally, the advantage that the two optical systems are always axially harmonised. Complicated adjustments, which are necessary in the case of separate systems for such axial harmonisation, are thus dispensed with.

Because the arrangement has the common scanning and representation system, likewise only one common input optical system is necessary. Thus, likewise the expenditure, the weight and the size of the entire device are reduced. It is possible to use, as input optical system, a tele-objective which is variable in focal width, so that the common field of vision of the two optical systems can be adapted to the target range and the distance of the missile from the guidance emplacement.

Further advantages and developments of the invention will become apparent from the sub-claims in conjunction with the following description, in which one exemplified embodiment of the invention is described in more detail with reference to the accompanying drawings, in which: Figure 1 is a schematic representation illustrating a device for guiding a missile into a target, in accordance with the invention, with a thermal-image apparatus as observation and possible target tracking apparatus and a laser transmitter for transmit ting guidance signals to the missile; and Figures 2a and 2b are respectively an elevation and a section taken along llb-llb of a polygonal wheel used as beam switch in the device in accordance with Figure 1.

The optical part of a guidance station or emplacement 1 is shown schematically in Figure 1. The guidance emplacement 1 has a thermal-image apparatus including a thermal-image receiver 2 as well as a laser transmitter 3. A common scanning and representation system 4 having a telescope 5 of variable focal width as common input optical system is provided for the thermal-image receiver 2 and the laser transmitter 3.

The scanning and representation system 4 has, following the telescope 5, an elevation scanning mirror 6 by which the beam path from the telescope is deflected in the direction of an intermediate optical system 7. This intermediate optical system 7 is, for example, a so-called Bouwers optical system having a parabolic mirror 8 and a hyperbolic deflection mirror arranged in the focal point thereof.

Provided between the parabolic mirror and the deflection mirror 9 there may additionally be a correction lens 10, as is indicated schematically in Figure 1. The beam path of the scanning and representation system extends from the elevation scanning mirror 6 to the parabolic mirrorS, is reflected from there onto the deflection mirror 9 and is thrown by this back onto the parabolic mirrorS.

The beam path then extends parallel to the beam path between the elevation scanning mirror 6 and the parabolic mirror 8 in the direction of a polygonal wheel 11 which rotates about a centric axis of rotation 12.

This polygonal wheel is shown in more detail in Figures 2a and 2b. The polygonal wheel 11 has, around its periphery, at uniform spacings, eight flat roof slopes or angled slopes 1 3a and 1 3b. The slopes 13a or 13b are respectively pitched towards the radius direction 14 of the polygonal wheel alternately opposingly at an angle a. If the rotary position of the polygonal wheel 11 in Figure 1 is such that the beam path is deflected by way of a slope 13a, then the beam path extends further in the direction A of the thermal-image receiver 2. If the rotary position of the polygonal wheel 11 is such that the beam path is deflected art a slope 136, then the beam path extends along B in the direction of the laser transmitter 3.The function of the described device is as follows: First of all the elevation scanning mirror 6 is set to the topmost line of the field of vision to be scanned.

The infra-red radiation incident or incoming into the guidance emplacement by way of the telescope 5 is, as described above, conducted through the optical system and is reflected by way of one of the slopes 1 3a into the thermal-image receiver 2. Through the rotation of the rotation wheel, because of the slope 1 3a this topmost line is scanned in the thermalimage receiver. The laser light emanating from the laser transmitter 3 is modulated in accordance with the guidance signals for the missile does indeed also fall onto this slope 13a, but is, because of the inclination thereof, conducted past the thermalimage receiver 2.If the polygonal wheel 11 further rotates, then the laser light now falls onto the next-following slope 13b and is conducted through the scanning and representation system 4 by way of the elevation scanning mirror 6, remaining in the same position, through the telescope. As a result of the rotation of the polygonal wheel, here likewise the topmost line of the common field of vision is swept with the laser beam. The infra-red radiation incident at the same time through the telescope 5 and deflected in the scanning and representation or display system 4 likewise falls onto the slop 13b, but is conducted past the thermal-image receiver 2.

Then the elevation scanning mirror 6 is adjusted to the next-following line, which is then scanned through the slopes 1 3a and 13b, following thereon, by the thermai-image receiver 2 and the laser transmitter 3. This procedure is repeated cyclically until the entire field of vision is scanned and then begins anew. Of course, the scanning movement of the elevation scanning mirror 6 and the rotary motion of the polygonal wheel 11 are coordinated to one another.

Instead of equipping the polygonal wheel with alternately inclined slopes and causing it to rotate about a fixed axis, it is possible to provide the slopes altogether with an inclination in the same direction.

Then, the alternate mirroring-in of the optical systems is effected by the polygonal wheel being swung periodically about its central point, whereby in turn the beam path of the common scanning and representation system extends at one time or hand in the direction A of the thermal-image receiver and at the other in the direction B of the laser transmitter.

The guidance signals sent out by the laser transmitter can be ascertained in the usual way in the thermal-image receiver. The missile can carry, for this purpose, on its tail, for example, a pyrotechnical flare composition or the iike, the displacement of which from the line of sight of the thermal-image apparatus is measured and is modulated into guidance signals.

Equally it is possible to design the thermal-image apparatus as an automatic target-tracking apparatus.

Claims

1. A device for guiding a missile into a target having two optical systems, preferably an observation apparatus for target observation and possibly target tracking and a guidance apparatus for transmitting guidance signals to the missile, in which the two optical systems are combined in a guidance station or emplacement, characterised in that both optical systems have a common optical scanning and representation or display system for line-form scanning of the common field of vision in elevation and azimuth, and in that the scanning and representation system has a periodically-controlled beam switch which mirrors or images the two optical systems linewise alternately into the scanning and representation system.

2. A device as claimed in claim 1, characterised in that the one optical system has a thermal-image apparatus for the target observation and possibly target tracking and the other optical system is a laser transmitter for the transmission of guidance signals to the missile.

3. A device as claimed in claim 1 or 2, characterised in that the periodically-controlled beam switch is a rotating driven polygonal wheel which has, around its periphery, as scanning elements for one scanning direction, flat slopes which are inclined with an angle of incidence (a) towards the radius direction, and in that the scanning and representation system has a further scanning element, such as an elevation scanning mirror, for the other scanning direction.

4. A device as claimed in claim 3, characterised in that consecutive slopes of the polygonal wheel all have the same centre angle with respect to the axis of rotation of the polygonal wheel, but have respectively oppositely equal angles of incidence (a) towards the radius direction, and in that the polygonal wheel is driven about a fixed axis of rotation which is perpendicular to the radius direction.

5. A device as claimed in any preceding claims, characterised in that the common optical scanning and representation or display system is an objective of variable focal length.

6. A device for guiding a missile into a target substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.