GB2175706A

GB2175706A - Laser guidance and tracking apparatus

Info

Publication number: GB2175706A
Application number: GB08610590A
Authority: GB
Inventors: Christian Diehl; Horst Kirsche; Gunther Reithmeier
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: Airbus Defence and Space GmbH
Priority date: 1985-05-02
Filing date: 1986-04-30
Publication date: 1986-12-03
Also published as: GB8610590D0; GB2175706B; FR2581450B1; DE3515687A1; DE3515687C2; FR2581450A1

Abstract

A guidance and tracking apparatus, for the control of projectiles by a beam following principle, comprises a guide beam laser 2 whose beam passes successively through two deflecting devices 3,4 and through a first beam expanding system 5, and a dichroic mirror 6 between the guide beam laser 2 and the deflecting mirrors 3,4 in such a way that light entering through the first receiving optical beam expanding system 5 is at least partly deflected to an infra-red camera 8. The output signals 13 from the camera may be fed to a signal processing circuit 16 connected with a central computer 12 which controls all the operating sequences of the guidance and tracking apparatus. Parallel to the output beam from the system 5 a reference beam is generated by a reference laser 10 and passed through a further beam expanding optical system 11. <IMAGE>

Description

SPECIFICATION Guide-beam and follow-up apparatus This invention relates to a guidance beam and tracking apparatus for the control of projectiles using a beam following method with a scanning laser beam and an optical arrangement comprising a guidance beam laser, a reference laser and a receiving means in parallel therewith and generally as disclosed in DEP 3441921.7.

In DEP 26 58 689 there is described a projectile guiding method wherein a laser beam deflected in a spiral path is used for controlling a flying object. This system does not include any tracking operation in respect of a sighting line directed towards the target.

In USP 4 111 383 there is described a projectile control device based on the beam following or "beamrider" principle, having lasers deflected in the direction of the X and Y coordinates in order to generate a guide beam.

The apparatus includes also a synchronization laser and a telescopic sighting device with means being provided for activating the synchronization laser at the instants at which the beams of the guide lasers, which are reflected into the sighting device, intersect the sight light to the target.- This type of tracking action is found to be slow in practice and also proves very inaccurate in comparison with the guiding of the projectiles by a guide beam.

The guide beam and tracking system described in DEP 3441 921.7 enables the target to be detected very accurately and projectiles to be controlled by the beamrider principle but this is only suitable for use in good atmospheric conditions and for certain applications.

In this invention a guidance beam and tracking apparatus is based on the beamrider principle, as in DEP 3441921.7, but is improved in such a way that a highly accurate target detection and tracking of the control system are provided, even under unfavourable weather conditions, while the necessity of coordinating the received apparatus and the guide beam transmitter is eliminated by a simplified construction.

According to this invention there is provided a guidance tracking apparatus for the control of projectiles using a beam following principle with a scanning laser beam and an optical arrangement comprising a guide beam laser, a reference laser and a receiving device aligned in parallel, wherein: a) the beam from a guide beam laser passes successively through two deflecting devices situated in mutually perpendicular coordinate directions and through a first beam expanding optical system having a variable focal length, b) a dichroic mirror being included in the path of the beam between the guide beam laser and the deflection devices in such a way that the beam received by the first optical system is at least partly directed to an infrared camera, and c) parallel to the output beam from the first expansion optical system a reference beam is provided generated by a reference laser and reflected by a further beam expanding optical system of variable focal length.

An embodiment according to the invention is described in the accompanying drawing by way of example only.

Referring to the drawing there is shown schematically a transmitting device for a reference laser and a guidance beam laser with a receiving device combined therewith. The guide beam 1, which is generated by the guide beam laser 2 comprising an Nd-YAIOlaser in this example, is controlled, if necessary, by means of a power switch 14.

A dichroic mirror 6 is inserted at a suitable point in the path of the beams 1, between the guide beam laser 1 and the deflecting mirrors 3, 4, in such a way that light entering through the first receiving optical beam expanding system 5 is mainly deflected to an infra-red camera 8 mounted to the side. The output signals 13 from the camera are fed to a signal processing circuit 16 connected with a central computer 12 which controls all the operating sequences of the guidance and tracking apparatus. The infra-red camera 8 can operate both in the 3-5 ,am light wavelength range and in the 8-14 Am range. A connection is provided, though not shown in the drawing, from the infra-red camera to a viewing device.

Due to the use of one and the same optical path for the guide beam laser and the receiving device, the need for the coordination device which would be required in apparatus involving separate light paths is eliminated.

Parallel with the ray path hitherto described is a reference laser 10 (of the Nd-YAIO type) which is controlled through a further beam expanding optical system 11 of the same kind and which emits a beam 9.

A particular advantage offered by the apparatus to which the invention relates resides in the fact that in certain applications, for example naval defence against missiles, the infra-red picture of the surroundings of the target and of the horizon is obtained simultaneously and synchronously with the scanning movement of the guide beam transmitter.

Through the signal processing circuit 16 connected to the infra-red camera, the central computer 12 continuously receives information concerning the particular point at which the target is present in the guide beam. This now makes it possible either to direct the guide beam to the target or to transmit the location of the target synchronously, by a data transmission system, to the projectile or missile to be controlled.

1. A guide tracking apparatus for the con

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Guide-beam and follow-up apparatus This invention relates to a guidance beam and tracking apparatus for the control of projectiles using a beam following method with a scanning laser beam and an optical arrangement comprising a guidance beam laser, a reference laser and a receiving means in parallel therewith and generally as disclosed in DEP 3441921.7. In DEP 26 58 689 there is described a projectile guiding method wherein a laser beam deflected in a spiral path is used for controlling a flying object. This system does not include any tracking operation in respect of a sighting line directed towards the target. In USP 4 111 383 there is described a projectile control device based on the beam following or "beamrider" principle, having lasers deflected in the direction of the X and Y coordinates in order to generate a guide beam. The apparatus includes also a synchronization laser and a telescopic sighting device with means being provided for activating the synchronization laser at the instants at which the beams of the guide lasers, which are reflected into the sighting device, intersect the sight light to the target.- This type of tracking action is found to be slow in practice and also proves very inaccurate in comparison with the guiding of the projectiles by a guide beam. The guide beam and tracking system described in DEP 3441 921.7 enables the target to be detected very accurately and projectiles to be controlled by the beamrider principle but this is only suitable for use in good atmospheric conditions and for certain applications. In this invention a guidance beam and tracking apparatus is based on the beamrider principle, as in DEP 3441921.7, but is improved in such a way that a highly accurate target detection and tracking of the control system are provided, even under unfavourable weather conditions, while the necessity of coordinating the received apparatus and the guide beam transmitter is eliminated by a simplified construction. According to this invention there is provided a guidance tracking apparatus for the control of projectiles using a beam following principle with a scanning laser beam and an optical arrangement comprising a guide beam laser, a reference laser and a receiving device aligned in parallel, wherein: a) the beam from a guide beam laser passes successively through two deflecting devices situated in mutually perpendicular coordinate directions and through a first beam expanding optical system having a variable focal length, b) a dichroic mirror being included in the path of the beam between the guide beam laser and the deflection devices in such a way that the beam received by the first optical system is at least partly directed to an infrared camera, and c) parallel to the output beam from the first expansion optical system a reference beam is provided generated by a reference laser and reflected by a further beam expanding optical system of variable focal length. An embodiment according to the invention is described in the accompanying drawing by way of example only. Referring to the drawing there is shown schematically a transmitting device for a reference laser and a guidance beam laser with a receiving device combined therewith. The guide beam 1, which is generated by the guide beam laser 2 comprising an Nd-YAIOlaser in this example, is controlled, if necessary, by means of a power switch 14. A dichroic mirror 6 is inserted at a suitable point in the path of the beams 1, between the guide beam laser 1 and the deflecting mirrors 3, 4, in such a way that light entering through the first receiving optical beam expanding system 5 is mainly deflected to an infra-red camera 8 mounted to the side. The output signals 13 from the camera are fed to a signal processing circuit 16 connected with a central computer 12 which controls all the operating sequences of the guidance and tracking apparatus. The infra-red camera 8 can operate both in the 3-5 ,am light wavelength range and in the 8-14 Am range. A connection is provided, though not shown in the drawing, from the infra-red camera to a viewing device. Due to the use of one and the same optical path for the guide beam laser and the receiving device, the need for the coordination device which would be required in apparatus involving separate light paths is eliminated. Parallel with the ray path hitherto described is a reference laser 10 (of the Nd-YAIO type) which is controlled through a further beam expanding optical system 11 of the same kind and which emits a beam 9. A particular advantage offered by the apparatus to which the invention relates resides in the fact that in certain applications, for example naval defence against missiles, the infra-red picture of the surroundings of the target and of the horizon is obtained simultaneously and synchronously with the scanning movement of the guide beam transmitter. Through the signal processing circuit 16 connected to the infra-red camera, the central computer 12 continuously receives information concerning the particular point at which the target is present in the guide beam. This now makes it possible either to direct the guide beam to the target or to transmit the location of the target synchronously, by a data transmission system, to the projectile or missile to be controlled. CLAIMS

1. A guide tracking apparatus for the con trol of projectiles using a beam following principle with a scanning laser beam and an optical arrangement comprising a guide beam laser, a reference laser and a receiving device aligned in parallel, wherein: a) the beam from a guide beam laser passes successively through two deflecting devices situated in mutually perpendicular coordinate directions and through a first beam expanding optical system having a variable focal length, b) a dichroic mirror being included in the path of the beam between the guide beam laser and the deflection devices in such a way that the beam received by the first optical system is at least partly directed to an infrared camera, and

c) parallel to the output beam from the first expansion optical system a reference beam is provided generated by a reference laser and reflected by a further beam expanding optical system of variable focal length.

2. An apparatus in accordance with Claim 1, wherein a central signal processing device serves to control the guide-beam laser, the reference laser, the deflection devices and the optical systems in accordance with the evaluated output signals of the infra-red camera.

3. An apparatus in accordance with Claims 1 and 2, wherein rapid deflecting mirrors are used in place of the deflecting devices.

4. Apparatus for guiding and tracking projectiles as described herein and exemplified by the drawings.