A SEMI-ACTIVE LASER SEEKER FOR MINIATURE, LASER-GUIDED MISSILE SYSTEMS

Abstract

The present invention relates to a semi-active laser seeker head for miniature, laser-guided missile systems comprising a housing (20) limiting an inner chamber (23); a lens element (40) that is seated in a gap (26) of the housing (20) reaching the inner chamber (23) so as to receive electromagnetic radiation. The laser seeker head comprises; a body (44) that has a convex surface (42) on which the lens element (40) gets completely seated in a gap (26) on one hand and that extends into the inner chamber (23) on the other hand; and a filter (52) that directly receives the electromagnetic radiation, which is focused by the convex surface (42), from the body (44) that lies before and selectively transfers it to a multi-channel sensor (56) arranged at the rear portion thereof based on a predetermined wavelength threshold.

Claims

1. A semi-active laser seeker head for miniature, laser-guided missile systems comprising a housing (20) limiting an inner chamber (23); a laser-permeable, particularly a transparent lens element (40) that is seated in a gap (26) of the housing (20) reaching the inner chamber (23) so as to receive electromagnetic radiation, characterized in that, it comprises; a body (44) that has a convex surface (42) on which the lens element (40) gets completely seated in a gap (26) on one hand and that extends into the inner chamber (23) on the other hand; and a filter (52) that directly receives the electromagnetic radiation, which is focused by said convex surface (42), from the body (44) that lies before and selectively transfers it to a multi-channel sensor (56) arranged at the rear portion thereof based on a predetermined wavelength threshold.

2. A laser seeker head according to claim 1, characterized in that, convex surface (42) is seated in an airtight manner such that it completes the gap (26) at the middle center of a front wall (21) of the housing (20) so as to a form of a dome.

3. A laser seeker head according to any one of the preceding claims, characterized in that, multi-channel sensor (56) comprises a mounting plate (54) that extends transversely in the inner chamber (23) in which the multi-channel sensor is positioned adjacent to the rear edge of the body (44) together with the filter (52).

4. A laser seeker head according to any one of the preceding claims, characterized in that, lens element (40) is composed of a material having a high refractive index of 1.50 or more, and particularly of ceramic.

5. A laser seeker head according to any one of the preceding claims, characterized in that, it comprises; a signal amplifier (60) that is connected to the multi-channel sensor (56) to provide signal transmission and is configured to amplify the electromagnetic radiation signal obtained by the multi-channel sensor (56).

6. A laser seeker head according to claim 5, characterized in that, it comprises; a gain controller (70) having a multi-channel amplifier (72) that is connected to the signal amplifier (60) so as to provide signal transmission and that is configured to selectively and separately amplify the electromagnetic radiation signal received from each channel of the multi-channel sensor (50).

7. A laser seeker head according to claim 6, characterized in that, it comprises; an adder circuit (84) arranged to determine the total signal value received from each channel by means of connecting with the multi-channel amplifier (72) so as to provide signal transmission, and a central controller (82) that activates a single-channel A/D element (86) to which it is connected, and compares it so as to identify the numerically largest signal in the sensed pulsed signal train (30) as the target source, in case the value of total signal provided from the adder circuit (84) exceeds a threshold value.

8. A laser seeker head according to claim 7, characterized in that, it comprises; a trigger circuit (85) that is provided to conduct electrical signals between the adder circuit (84) and the central controller (82), and that is arranged so as to send a pulse monitoring signal that activates the single-channel ND element (86) to the central controller (82) in case of excess by means of comparing the threshold value with the total signal value received from the adder circuit (84).

9. A laser seeker head according to claim 8, characterized in that, it comprises; a multi-channel A/D element (83) in which the central controller (82) is connected such that it conducts electrical signal, and is configured so as to activate said central controller (82) such that the data received by the multi-channel sensor (56) are individually digitized and transferred to the central controller (82) when a pulse monitoring signal sent by the trigger circuit (85) is received by the central controller (82) and at the moment the quantitively largest pulse is observed.

10. A laser seeker head according to claim 9, characterized in that, the central controller (82) is configured to determine the laser pulse sensed from the digitized data received from the multi-channel A/D element (83) by means of calculating the normalized orientations of the laser pulse with respect to the seeker head axis.

11. A laser seeker head according to claims 8-10, characterized in that, the central controller (82) is configured so as to increase the gain level of the multi-channel amplifier (72) to a predetermined level in case the total signal value provided from the adder circuit (84) remains under the predetermined threshold value.

12. A laser seeker head according to claims 8-11, characterized in that, the central controller (82) is configured so as to adjust the gain level of the multi-channel amplifier (72) to the highest value provided by the multi-channel amplifier (72) in case the total signal value provided from adder circuit (84) remains under the predetermined threshold value.

13. A laser seeker head according to any one of the preceding claims, characterized in that, the multi-channel sensor (56) comprises four identical quadrant structures divided symmetrically to one another.

14. A miniature missile (10) comprising a laser seeker head according to any one of the preceding claims.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0018] FIG. 1 illustrates the schematic view of the scattering of the laser shooting from the target and other environmental elements provided from a source for a laser seeker head owned by a miniature missile.

[0019] FIG. 2 illustrates the outer view and the cross-sectional view of a representational embodiment of the inventive laser seeker for the inventive miniature guided missile in assembled state.

[0020] FIG. 3 illustrates the perspective view of the embodiment shown in FIG. 2 in a disassembled state.

[0021] FIG. 4 illustrates the schematic view of a representational embodiment of the operating system of the laser seeker head.

[0022] FIG. 5 illustrates the graphical view of the pulsed signal train arriving at the laser seeker head from the laser source.

DETAILED DESCRIPTION OF THE INVENTION

[0023] In the detailed description provided herein, the inventive innovation is described only to provide a better understanding of the subject matter by examples and references and without constituting any limiting effect.

[0024] FIG. 1 representationally illustrates a 40 mm miniature missile (10) aimed at a target (4). The laser seeker head is a subsystem that notifies the location of the target (4) to the laser-guided miniature missile (10) by means of sensing the reflected radiation from the target (4) marked by a laser designator (1) as a successive great number of pulsed signal trains (30). The laser designator (1) senses more than one reverse reflection in most shooting scenarios. Said reverse reflections consist of scatterings at the moment of the beam exit from the laser designator (1), natural or artificial external obstacles (2) to which part of the laser touched in the line of marking, water vapor forming atmospheric obstacles (3), scatterings caused by smoke and density, and the rebound of the laser (L) flooding from the edges of the marked target (4) from the further rear obstacles (5).

[0025] FIG. 2 illustrates both the outer view and the cross-sectional view of the inventive semi-active laser seeker head used in the miniature missile (10). The laser seeker head comprises a housing (20) having a cylindrical form with a dome-shaped end surrounding an empty inner chamber (23) so as to form an end portion of the miniature missile (10). A flat rare edge (24) of the housing (20) is formed a mouth that may be accessed externally to the cavity created by the inner chamber (23) when the housing (20) is disassembled. There are mounting recesses (25) in the structure of holes distanced from one another on the rear edge (24). The mounting recesses (25) assist that the housing (20) is mounted on the body of the miniature missile (10). A front wall (21) of the housing (20) opposite the rear edge (24) has the structure of a dome in which a circular gap (26) with a cut-off end accessible to the inner chamber (23) is situated. A lens element (40) is produced from a ceramic material having a solid and high refractive light-permeable index as one piece. The front end of the lens element (40) comprises a convex surface (42). The convex surface (42) circumferentially and completely engages the gap (26) in an airtight manner. The rear part of the convex surface (42) forms a cylindrically continuing body (44). A laser pulsed signal train (30) moves from within the body (44) by highly refracting from the gap (26) by means of convex surface (42). A sensing assembly (50) is provided in the inner chamber (23) at the rear part of the body (44). In sensing assembly (50), a circular filter (52) has been fixed transversely in the inner chamber by means of a mounting plate (54) so as to fall on the image focused by the convex surface (42) behind the body (44). A signal amplifier (60), a gain controller (70), and an electronic control unit (80), each one of them has a structure of an integrated and coaxial board, extend transversely in an adjacent order in the inner chamber (23) along the circumferential edges, distantly separated from each other by means of one each mounting pin (61, 71, 81). Thus, a very compact controlling system is fitted into the housing (20) of the inner chamber (23) at the front part of the 40 mm miniature missile.

[0026] FIG. 3 illustrates the perspective view of components in a disassembled state in the inner chamber (23). There is a multi-channel sensor (56) having a quadrant divided into four segments in a plus shape behind the circular filter (52), on the side of the mounting plate (54) facing the filter (52). The filter (52) is seated coaxially such that it directly and completely covers the circular multi-channel sensor (56).

[0027] Thus, filter (52) seats on the flat and circular rear face of the body (44) from one front face, and on the multi-channel sensor (56) from its rear face. The pins of the multi-channel sensor (56) of the sensing assembly (50) are located on the rear face of the mounting plate (54). Pins run through the corresponding slots (63), which have a hole structure from one end to the other and reach the signal amplifier (60) that has a circular, coaxial plate structure. The signal amplifier (60) is connected with the multi-channel sensor (56) so as to provide analog signal transmission. The signal amplifier (60) includes an amplifier circuit (62) on its rear face and is seated from the rear at a distance from a gain controller (70) having a circular coaxial board structure. The gain controller (70) carries a multi-channel amplifier (72) thereon. An electronic control unit (80) with the structure of an integrated board having a central processor is leaned on the gain controller (70) from the rear at a distance.

[0028] FIG. 4 illustrates an operation scheme of the seeker head. The seeker head has two A/D (the expression of Analog to Digital is referred to as A/D) converters. One of said converters is a fast single-channel A/D element (86) that digitizes the total signal (Ts) obtained from all of the channels of the multi-channel sensor (56) having four quadrants, and the other one is a multi-channel A/D element that separately digitizes the signals receiving from the 4 channels. Fast A/D may digitize separate laser pulses received at a frequency of 1 ρs. The slow multi-channel A/D element separately digitizes the outputs of all channels within 100 ρs, and data to be utilized in order to calculate the angular location of the target (4) in accordance with the miniature missile (10) axis is obtained by means of using said data.

[0029] The central controller (82) owned by the electronic control unit (80) on the munition records the intensities of laser pulsed signal trains (30) at a frequency of 1 ρs received from the fast single-channel A/D element (86) and the time difference between them. It assumes that the target (4) always has the highest reflection signal intensity. Laser designators (1) send laser pulses at fixed intervals and the frequency of the pulses sent by said laser designators (1) never exceeds 20 Hz. This means that there is a huge time difference between the pulsed signal trains composed of reflection and scattering. FIG. 5 illustrates the schematic view of the said situation. The lateral and ascending angular positions of the signal having the highest intensity in said pulsed signal trains (30) are calculated by the central controller (82) in accordance with the direction of the miniature missile (10) by means of using the data obtained from the multi-channel A/D element (83). Thus, it is ensured that the seeker head produces information that directs the munition to the correct target (4).

[0030] The working principle of the laser seeker head is as follows; Laser pulses exiting from the laser designator (1) and reflecting from the target (4) reach the seeker lens element (40). Additionally, they are optically filtered by the filter (52) in which they reached from the body (44) by focusing on the convex surface (42) over the lens element (40) together with the second laser pulses originates due to the reasons such as scattering and reflection, and they are sensed by means of the multi-channel sensor (56) having four equal segments which have first, second, third and fourth channels (A, B, C, D), respectively. The signals exit from the 4 segments (A, B, C, D) of the multi-channel sensor (56) pass through the front amplifier circuit (62) acting as a preamplifier, and multi-channel amplifier (72) that is variably gainful, respectively, then reach an adder circuit (84) for 4 channels. Herein, 4 channel (A, B, C, D) signals are turned into TS total signal. TS is sent to a trigger circuit (85). The trigger circuit (85) generates a laser pulse observation signal and transmits it to the central controller (82) in case the TS signal is higher than a certain threshold level. The central controller (82) is configured so as to examine the magnitude of the laser pulses sensed over the fast single-channel A/D element (86). Laser pulse signal train (30) decides the quantitatively largest signal inside is the target (4) and operates multi-channel A/D element (83) in order to individually digitize the segment data of multi-channel sensor (56) at the moment of the large pulse is observed. The electronic control unit (80) finds the normalized orientations of the sensed laser pulse with respect to the seeker head axis, that is, to miniature missile (10) extension axis by means of using the received data.

[0031] In case there is no sensed signal, the front signal amplifier (60) gets activated. Again, in case there is no sensed signal, the gain level is increased by means of utilizing the central controller (82) which is a variable gain amplifier, and also a multi-channel amplifier (72) until the signal is sensed. It remains in a standby state at the highest gain level until the signal is sensed if still no signal is sensed. They are utilized through the signal amplifier (60), which is the pre-amplifier, and the central controller (82), which is a variable gain amplifier.

TABLE-US-00001 REFERENCE NUMERALS 1 Laser Designator 2 External Obstacle 3 Atmospheric Obstacle 4 Target 5 Rear Obstacle 10 Miniature Missile 20 Housing 21 Front Wall 23 Inner Chamber 24 Rear Edge 25 Mounting Recess 26 Gap 30 Pulsed Signal Train 40 Lens Element 42 Convex Surface 44 Body 50 Sensing Assembly 52 Filter 54 Mounting Plate 56 Multi-Channel Sensor 60 Signal Amplifier 61 Connecting Pin 62 Amplifier Circuit 63 Slot 70 Gain Controller 71 Connecting Pin 72 Multi-Channel Amplifier 80 Electronic Control Unit 81 Connecting Pin 82 Central Controller 83 Multi-Channel A/D Element 84 Adder Circuit 85 Trigger Circuit 86 Single-Channel A/D Element A First Channel B Second Channel C Third Channel D Fourth Channel L Laser Mark