Missile seekers

Abstract

A sensor for a missile seeker includes a primary, concave, reflector that is reflective to RF waves and to another kind of waves, but that includes a transmissive region, through which RF waves can pass. A secondary, convex, reflector is reflective to RF waves but transmissive, and not reflective, to the other kind of waves, and is arranged facing the primary reflector to further reflect RF waves reflected by the primary reflector through the transmissive region of the primary reflector. An RF detector is arranged on the opposite side of the primary reflector from the secondary reflector and arranged to detect the RF waves reflected by the secondary reflector through the transmissive region of the primary reflector. A second detector, for detecting the other kind of waves, is arranged on the opposite side of the secondary reflector from the primary reflector and is arranged to detect the other kind of waves after they are reflected by the primary reflector and transmitted through the secondary reflector.

Claims

1. A sensor for a missile seeker, the sensor comprising: a primary, concave, reflector that is reflective to RF waves and to another kind of waves, but that includes a transmissive region, through which RF waves can pass; a secondary, convex, reflector that is reflective to RF waves but transmissive to the other kind of waves, and is arranged facing the primary reflector to further reflect RF waves reflected by the primary reflector through the transmissive region of the primary reflector; an RF detector for detecting RF waves, arranged on the opposite side of the primary reflector from the secondary reflector and arranged to detect the RF waves reflected by the secondary reflector through the transmissive region of the primary reflector; and a second detector, for detecting the other kind of waves, the second detector being arranged on the opposite side of the secondary reflector from the primary reflector and being arranged to detect the other kind of waves after they are reflected by the primary reflector and transmitted through the secondary reflector.

2. A sensor as claimed in claim 1, in which the other kind of waves is an electromagnetic (EM) wave.

3. A sensor as claimed in claim 1, in which the other kind of waves is an acoustic wave.

4. A sensor as claimed in claim 1, in which the secondary reflector is on the front surface of a convex solid supporting structure.

5. A sensor as claimed in claim 1, in which the second detector is a quadrant detector, an imager or an intensity detector.

6. A sensor as claimed in claim 1, in which the sensor includes LADAR apparatus, and the second detector is a detector of the LADAR apparatus.

7. A sensor as claimed in claim 1, in which the concave primary detector focuses the other kind of waves on the second detector.

8. A sensor as claimed in claim 1, in which the other kind of waves is out of focus at the second detector.

9. A sensor as claimed in claim 8, in which the sensor includes an imager and the imager includes or is connected to an image processor and the second detector is configured to provide an out-of-focus image of the other kind of waves to the imager, the image processor being configured to sharpen in software the out-of-focus image.

10. A sensor as claimed in claim 1, in which the other kind of waves comprises two or more wavelengths.

11. A sensor as claimed in claim 1, in which the RF waves comprise two or more carrier wavelengths.

12. A sensor as claimed in claim 1, in which the primary reflector is reflective of, the secondary reflector is transmissive of, and the second detector is arranged to detect, at least one further other kind of wave.

13. A sensor as claimed in claim 1, in which a third detector for detecting yet another kind of waves is provided behind the primary reflector.

14. A sensor as claimed in claim 1, in which the primary reflector is configured to be steerable when it is mounted inside a missile and the secondary reflector is configured to move with the primary reflector as the primary reflector is steered.

15. A sensor as claimed in claim 1, further comprising a low-light camera or thermal imager.

16. A sensor as claimed in claim 15, wherein the thermal imager operates in the mid-IR or the long IR.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Example embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, of which:

(2) FIG. 1 is a schematic cross-section of the nose region of a missile including a multimode sensor according to an example embodiment of the invention;

(3) FIG. 2 is a schematic perspective view of the multimode sensor of FIG. 1; and

(4) FIG. 3 is a schematic perspective view of a multimode sensor according to another example embodiment of the invention.

DETAILED DESCRIPTION

(5) In an example embodiment of the invention, the nose region 10 of a missile includes a multimode sensor 20 arranged behind the radome 30 of the missile. The sensor 20 comprises a Cassegrain telescope formed by a primary reflector 40, a secondary reflector 50, an RF detector 60 for detecting RF radiation 70 and an IR detector 80 for detecting IR radiation 90. The primary reflector 40 includes an aperture 100. The RF detector 60 is arranged behind the primary reflector 40. The IR detector 80 is arranged behind the secondary reflector 50.

(6) The secondary reflector 50 is dichroic. It is reflective to RF radiation 70 and transparent to IR radiation 90.

(7) RF radiation 70 incident on the radome 30 passes to the primary reflector 40, is focused towards the secondary reflector 50 and then through the aperture 100 to the RF detector 60. IR radiation 90 incident on the radome 30 also passes to the primary reflector 40 and is focused towards the secondary reflector 50. However, the IR radiation 90 passes through the secondary reflector 50 to the IR detector 80.

(8) In this example embodiment, the IR radiation 90 is generated by a laser designator, and has a wavelength of 1064 nm. The IR detector 80 is a quadrant detector that detects a defocused spot of IR radiation.

(9) The primary reflector 40 is mounted (FIG. 2) within a missile nose using a support bar 110. The support bar 110 passes through a cuboidal clamp 120, which includes flanges 130. The primary reflector 40 is bolted, via a support disk 140, to the flanges 130 of the clamp 120. The central aperture 100 of the primary reflector 40 extends through the disk 140, bar 110 and clamp 120. The RF detector 60 is independently mounted within the missile nose, behind the bar 110 and coaxial with the primary reflector 40, so that it receives RF waves that pass through the aperture 100. The IR detector 80 is mounted on the primary reflector 40. The IR detector 80 is welded to mounting struts 150, which pass through the periphery of the primary reflector and the other ends of which are retained behind the primary reflector by brackets 160. The secondary reflector 50 is mounted on (or, in some embodiments, close to) the surface of the IR detector 80 that faces the primary reflector 40.

(10) In another example embodiment of the invention (FIG. 3), a thermal imager 85 is additionally arranged behind the primary mirror 40. In this embodiment, the IR detector 80 detects near IR radiation. The secondary reflector 50 is reflective to thermal IR radiation 95, as well as RF radiation 70, but is not reflective to near IR radiation 90. A splitter 65 is positioned between the primary reflector 40 and the RF detector 60; it transmits RF radiation 70 to the RF detector but reflects thermal IR radiation 95 to the thermal IR detector 85. Thus, the sensor behaves like that of the embodiment of FIGS. 1 and 2, but additionally provides images in the thermal IR, with the thermal IR radiation 95 following the same path as RF radiation 70 through the Cassegrain telescope formed by the first reflector 40 and the second reflector 50, save that, after passing through the aperture 100, the thermal IR radiation 95 is reflected to the thermal IR imager 85 by the splitter 65.

(11) Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

(12) For example, in another example embodiment of the invention, the IR detector 80 is an imaging array positioned so that the IR rays 90 are focused upon it. In another example embodiment of the invention, the IR detector 80 is an imaging array positioned so that the IR rays 90 form an unfocused image upon it; software is employed to sharpen the image.

(13) In example embodiments of the invention, the RF detector 60, the IR detector 80, or both are configured to detect radiation at a plurality of wavelengths; for example, in example embodiments of the invention, the IR detector 80 is a two-colour array.

(14) Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may be absent in other embodiments.