Laser fire control system small boat application

[57] ABSTRACT

A small boat surface to surface weapon control system comprising search radar, TV camera, laser transmitter and a semi-active guided missile is disclosed. The target is initially located by radar scanning devices and the bearing is transferred to a television camera mechanism which is mounted on the same mast as the radar antenna. The television camera and a laser gun will then be pointed in the direction of the target. A blossom on a television screen which coincides with the image of the target indicates that the laser gun is on line with the target. The missile is fired and rides a reflected laser beam to the target.

Claims, 2 Drawing Figures

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PATENTED AUG 21 BW

3.754.249

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FIG. I

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FIG. 2

INVENTOR

STUART D. KEARNEY π

BY

ATTORNEY

3,754,249

LASER FIRE CONTROL SYSTEM SMALL BOAT APPLICATION

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

The invention relates to a fire control system for small boats and more particularly to a fire control system utilizing laser beam guidance means for missiles carrying warheads.

Increased emphasis has been placed recently on both the utilization of small boats and their associated fire power for coastal defense and incipient insurgency actions. Improvements in the fire power of small boats has been dormant since the use of PT boats in World War II. Torpedoes have limited versatility while gun fire has a poor first shot kill probability.

The first control system described in this invention fulfills a small boat requirement by being versatile and light weight while still providing an inherent accuracy for the delivery of a medium size (12-50 lbs.) warhead. This fire power gives a small boat the impact of a 5inch, 38 caliber gun which is employed as first line armament by a 22 hundred ton Naval destroyer.

SUMMARY OF THE INVENTION

The basic elements of the fire control system comprising the invention are the boat’s surface search radar, a TV camera for area display, a laser transmitter, and a semi-active guided missile. The boat’s surface radar seeks out, identifies and ranges a prospective target. A television camera presents the real world image of the target to an operator Who brings the laser beam transmitted from the laser transmitter on target by coinciding the reflected laser beam appearing as a bios- 40 som on the television screen with the real world image of the target. Such a Coincidence indicates that the laser beam is on target. The semi-active guided missile may be launched so as to intercept the path of the reflected laser beam which it will then follow to the tar- 45 get.

OBJECTS OF THE INVENTION

An object of this invention is to provide a small surface vessel with fire power potentially equivalent to a 50 destroyer.

Another object of this invention is to provide destroyer fire power capabilities to small surface vessels while still providing a versatile, light-weight, and accurate weapon control system.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, in graphical form, a target vessel and an attacking vessel using the fire control system of the invention; and

FIG. 2 illustrates a television display on-board the attacking vessel using the weapon control system of the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is illustrated the functional relationship of the elements comprising the invention. A small surface vessel is adapted to carry a greatly increased fire power capability by the installation of missiles on its deck. The control of these missiles, which are capable of carrying medium size warheads, is the responsibility of the invention disclosed. The boat’s surface search radar, which renders range and azimuth or bearing indications on a PPI type radar display, is used to initially detect a potential target, as illustrated by the parabolic antenna 11 and radar beam 12 of FIG. 1.

Upon detection of a potential target, a small television camera 13 may be focused on said target by adjusting the camera to the bearing of the parabolic rotating antenna 11. The television camera may be mounted in proximity with the boat’s radar antenna on the same mast. The camera will present a real world image as determined by light rays 14, on a television screen display within the ship.

Upon the initial detection and identification of the target, a laser transmitter 10 of a solid state type commonly known as an optical maser which is mounted on the same mast as the vessel’s radar antenna and television camera is used to establish a laser path to the target. The television camera 13 and laser transmitter 10 are mounted in proximity to the reflecting antenna of the ship’s radar system as illustrated in FIG. 1.

Referring now to FIG. 2, reference is made to laser beam blossom 19 which is created by the transmitted laser beam 15 reflecting from the target 17, A defense control crew on the small vessel employing the invention, may manipulate laser transmitter 10 so as to cause a coincidence between laser blossom 19 and target 18. Upon coincidence, an operator is assured that the laser transmitter 13 is directing laser beam 15 on target.

Activation of the missile launcher will cause the missile to be projected along a trajectory 16 which will intercept the reflection of laster beam 15. A laser beam detector mounted in the head of the missile is activated upon the missile’s interception of the reflected laser beams. The detector is effective to cause the missile to follow the reflected laser beam to the target.

The laser beam detector mounted in the head of the guided missile may be of the rotation field type or it may be a four element photodiode. The four element photodiode is more ideally suited for laser centering systems. It comprises four elements each consisting of a silicon Schottky photodiode. Mounted together the diodes have an active area diameter of 0.450 inches. Each of the four quadrants of the active area are separated by a spacing of 0.005 inches. Position of a light spot on the photodiode is determined by the current in each clement. By use of this detector and associate servo-mechanisms, the missile rides the beam on a collision course to the target.

Both the television camera and laser transmitter may be manually maintained on target. The television camera and the laser transmitter are stabilized on the boat’s mast to permit the line of sight from boat to target to remain on target.

The laser weapons control system disclosed fulfills the requirement for a light-weight missile fire control system for small boats. It further provides reliability,

3,754,249 easy and minimum maintenance and relatively low cost. These advantages are inherent in the system because its subcomponents are reliable field performance proven equipment.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings.