U.S. patent application number 10/495147 was filed with the patent office on 2004-12-30 for proximity sensor, especially for ignition of the warhead of a shell directed against an aprroaching missile.
Invention is credited to Steuer, Raimar, Warm, Berndt.
Application Number | 20040261646 10/495147 |
Document ID | / |
Family ID | 27740384 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040261646 |
Kind Code |
A1 |
Steuer, Raimar ; et
al. |
December 30, 2004 |
Proximity sensor, especially for ignition of the warhead of a shell
directed against an aprroaching missile
Abstract
A proximity sensor (11) is intended to initiate the warhead of a
defence shell which is fired against an attacking projectile from
the object to be protected in order to interfere with or even
destroy the functionality of the attacker. For that purpose the
proximity sensor (11) should not yet respond to the attacker which
is to be defended against by the shell appearing ahead in the
direction of flight thereof; rather, the proximity sensor is to
respond only when the attacker to be defended against is detected
ahead inclinedly at an operatively optimal distance. Such a
response characteristic in the form of the wall of a hollow cone is
afforded if an annular detector element (12) is arranged in the
image focus plane behind a positive cylindrical lens (14).
Inventors: |
Steuer, Raimar; (Leinburg,
DE) ; Warm, Berndt; (Schwaig, DE) |
Correspondence
Address: |
Leopold Presser
Scully Scott Murphy & Presser
400 Garden City Plaza
Garden City
NY
11530
US
|
Family ID: |
27740384 |
Appl. No.: |
10/495147 |
Filed: |
May 10, 2004 |
PCT Filed: |
February 15, 2003 |
PCT NO: |
PCT/EP03/01528 |
Current U.S.
Class: |
102/213 |
Current CPC
Class: |
F42C 13/02 20130101 |
Class at
Publication: |
102/213 |
International
Class: |
F42C 013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2002 |
DE |
102 07 923.4 |
Claims
1. A proximity sensor (11), for initiating the triggering of the
warhead of a defensive shell directed against an approaching
projectile, characterised in that said sensor has a response
characteristic in the form of a hollow cone (beams 18).
2. A proximity sensor according to claim 1 characterised in that it
said sensor has an annularly responsive detector element (12) in an
image focus plane behind a positive cylindrical lens (14).
3. A proximity sensor according to claim 2 characterised in that
the cylindrical lens (14) is a bar with convex entry and exit end
faces (16, 17).
4. A proximity sensor according to claim 2 or claim 3 characterised
in that the cylindrical lens (14) comprises an infrared
radiation-conducting material with a high refractive index in
relation to air.
5. A proximity sensor according to claim 2 characterised in that
the detector element (12) is arranged in a protective housing (20)
behind a window (21).
6. A proximity sensor according to claim 5 characterised in that
the detector element (12) is mounted behind a flattened centre,
surrounded by a convex annular zone (22), of the exit end face
(17).
7. A proximity sensor according to claim 4, characterised in that
said infrared radiation-conducting material is selected from the
group of materials consisting of germanium and silicon.
Description
[0001] The invention concerns a proximity sensor as set forth in
the classifying portion of claim 1.
[0002] Such a proximity sensor is required for an active defence
system in which the object under attack fires against the attacking
projectile, in accordance with U.S. Pat. No. 5,661,254A a defence
shell with a fragmentation warhead or, in accordance with U.S. Pat.
No. 6,244,156B1, a defence shell with a blast warhead. The attacker
may be a projectile which is fired without a drive (shell) or a
projectile fitted with its own drive (missile). The defence is
implemented by damage to or triggering of the firing sensor system
of the attacker or by influencing the attack trajectory thereof.
Such a scenario is diagrammatically illustrated for a case by way
of example in DE 196 01 756 C1. As shown therein it cannot
realistically be assumed that a collision will take place between
the attacker and the defence shell. Therefore the warhead of the
defence shell must be fired immediately prior to its flying past,
because that then affords the optimum combat situation relative to
the attacker, for the fragmentation or blast action of the defence
shell.
[0003] Radar fuses are used for distance triggering in relation to
aerial targets. Their lobe-shaped sensitivity characteristic
however does not afford clear and reproducible firing information,
in the illustrated passing situation. A particular disadvantage
with radar fuses is that they also and even preferably lead to
target contact in a direction coaxially ahead, and thus in a
proximity situation, which is extremely disadvantageous in terms of
the distance involved and for the radially oriented action of the
defence warhead.
[0004] In consideration of those factors the object of the present
invention is to provide a proximity sensor for operatively
optimised triggering of the warhead of a defence shell.
[0005] According to the invention that object is attained by the
essential features recited in claim 1. In accordance therewith the
reception characteristic of the proximity sensor according to the
invention describes the wall of a hollow cone which is coaxial with
respect to the system axis of the defence shell and which opens
ahead in the direction of flight, towards the approaching attacker.
The proximity sensor responds, that is to say results in initiation
of the defence warhead, when the attacker to be defended against
passes the wall of the hollow cone. By virtue of the cone geometry,
that event is correspondingly further in front of the defence
shell, the greater the respective radial distance from the axis of
the system and thus from the trajectory of the defence shell. As a
result the effect of the warhead (a fragmentation cone which is
propagated radially therearound or a corresponding pressure wave)
has a correspondingly longer time to be propagated inter alia in a
direction towards the approaching attacker, the further away it is
when fuse triggering takes place. In contrast an approximately
coaxial proximity situation is not detected by the sensor because
that takes place in the insensitive interior of the hollow cone. As
long as the attacker to be defended against is approaching in the
interior of the hollow cone configuration of the sensor
characteristic therefore, the sensor does not yet respond, as is
desired, because the effect of the defence warhead is not oriented
axially ahead but radially with respect to the defence trajectory;
therefore, fuse triggering is delayed until a lateral flypast
situation is impending.
[0006] Preferably the proximity sensor is operated
optoelectronically in the infrared range, for detecting heated tips
and edges of the attacker; more specifically by means of a cylinder
of thermooptically conducting material, the mutually opposite end
faces of which are convex. In regard to radiation geometry, this
provides that each beam which is incident through the entry end
face into that cylinder lens inclinedly at a given angle relative
to the axis of the system is refracted towards the axis of the
system and thus towards the edge region of the exit end face which
is also convex and shortly after issuing there passes through a
focal point. A detector with an annular active zone is arranged at
that focal point distance behind the rearward convex end face.
Associated with a given spacing from the edge of the exit end face,
corresponding to the diameter of the annular detector zone, is a
given angle of incidence into the entry end face. That angle of
incidence is correspondingly more greatly inclined with respect to
the longitudinal axis of the system, for a given detector radius,
and the sensor characteristic therefore has a correspondingly
larger cone angle, the greater the refractive index of the material
of the cylinder in relation to air. As is known, that index is
about 1.5 in the case of optical glass, about 3.5 in the case of
silicon and about 4.0 in the case of germanium. The detector
therefore reacts to a hot spot passing into the sensor beam path
which is in the shape of a hollow cone, with its cone spread angle
being determined by the geometry and the material of the
cylindrical lens.
[0007] Further features and advantages of the structure according
to the invention and additional developments will be apparent from
the further claims and from the description hereinafter of a
preferred embodiment of the proximity sensor according to the
invention, which is diagrammatically shown in the drawing in highly
abstracted form, being limited to what is essential, and not being
true to scale. The single FIGURE of the drawing is a view in axial
longitudinal section through the beam path through positive lens of
cylindrical shape, behind which the actual detector element is
arranged in the image focus plane.
[0008] The thermooptical proximity sensor 11 diagrammatically shown
in the drawing substantially comprises an annular detector element
12 which is mounted coaxially with respect to the axis 13 of the
system behind a long cylindrical lens 14 of silicon or germanium.
That cylindrical lens 14 can be considered as being cut out of a
thick positive (that is to say convex at both sides) lens shape 15
in coaxial relationship with the axis 13 of the system. In the
cylindrical lens 14 therefore disposed axially opposite to a convex
entry end face 16 is an exit end face 17 which is also convex (but
which does not necessarily involve the same curvature).
[0009] A parallel beam 18 which enters the convex entry end face 16
at a given inclination with respect to the axis 13 of the system is
refracted by virtue of the beam-geometric aspects as
diagrammatically illustrated towards the axis 13 of the system in
the denser material and is concentrated onto a small exit region
near the edge, which is dependent on the angle of incidence, in the
exit end face 17 which is also convex. The focus is on the other
side of the exit end face 17. Arranged at that focus is the
detector element 12 disposed in a protective housing 19 behind a
thermal window 20. As the detector element 12 is intended to detect
only the edge region corresponding to a given angle of incidence,
it is either in the form of an annular disc of suitable diameter
and ring width; or a disc-shaped detector is covered over centrally
so that only that ring zone is caused to respond. In this respect
it is to be borne in mind that this plane-parallel disc of the
window 20, due to the refractive action, on the way to the focus,
results in further displacement of the beam path, as is known from
geometrical optics as a refraction phenomenon when passing through
a parallelepiped.
[0010] In order to be able to maintain the small distance for the
focus behind the cylindrical lens 14 for positioning of the
detector element 12, its convex exit end face 17 is ground flat in
the centre transversely with respect to the axis 13 of the system
in order here to fix the protective housing 19 with its window 20.
The ground face is preferably matted or lacquered so that only the
above-mentioned annular region of the detector element 12 can be
subjected to the radiation effect. All that remains of the convex
exit end face 17 therefore for the beam to pass therethrough is
only a narrow concentric ring zone 22, along which the exit region
19 is displaced around the axis 13 of the system when the entry
beam 18, while maintaining its inclination, is rotated about the
axis 13 of the system, as is diagrammatically shown in the drawing
for two entry angles which are emphasised in isolation. The
sensitivity characteristic in the form of the wall of a hollow cone
(represented by the beams 18), by way of the annular zone 22 at the
exit end, therefore results in imaging of the individual incident
rays on the annular detector element 12 which is disposed in the
image focus plane of the beam path. That annular imaging effect
involves an angle of incidence of the beams 18 with respect to the
axis 13 of the system, which is correspondingly steeper, the
greater the refractive index of the material constituting the
cylindrical lens 14. Preferably therefore germanium or at any event
silicon is used for that purpose.
[0011] As can be seen from the beam diagram and the detector
element 12 which is responsive in an annular configuration, that
proximity sensor 11 is insensitive ahead in the direction of its
axis 13; it responds only when a heat-radiating object (here in
particular the attacker which is to be defended against) passes
into the inclined beam path in the shape of a hollow cone.
[0012] In accordance with the invention therefore there is provided
a proximity sensor 11 for the radially operative warhead of a
defence shell which is fired against an attacking projectile from
the object to be protected in order to interfere with or even
destroy the functionality of the attacker. That proximity sensor 11
does not yet respond to the attacker which is to be defended
against by the shell appearing ahead in the direction of flight
thereof; rather, the proximity sensor is to respond only when the
attacker to be defended against is detected ahead inclinedly at an
operatively optimal distance. Such a response characteristic in the
form of the wall of a hollow cone is afforded if an annular
detector element 12 is arranged in the image focus plane behind a
positive cylindrical lens 14.
* * * * *