AU595529B2 - Laser rifle sight - Google Patents

Description

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APPLICANT:

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FILING DATE: MONARO RESEARCH LABORATORIES PTY GTD PH 00652 21 MAY 85 kZ-RALIAN MAY 1986 -INT ,OFFC FORM COMMONWEALTH OF AUSTRALIA The Patents Act 1952 COMPLETE SPECIFICATION FOR AN INVENTION ENTITLED: LASER RIFLE SIGHT The following statement is a full description of this invention, including the best method of performing it known to me: f cI

ABSTRACT

This invention relates to a system for laser beam sighting and target identification using hand-.held rifles, fixed or mobile guns or missile launchers, consisting of an annular laser beam generator, laser beam scanner for target identification, image wavelength converter/intensifier, image processing modules and facilities for remote control of the t firing sequence.

The invention has application in police and military operationr with the safety of the rifleman being paramount.

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S S FIELD OF THE INVENTION This invention relates to a sy-tem for laser beam sighting and target identification using a hand-held rifle or fixed or mobile gun or missile launcher, consisting of a laser beam generator, laser beam scanner and a laser power supply all mounted on said rifle or attached to or positioned near to a gun or missile launcher the output of said laser aiming beam being collimated in such a manner that the t central portion of the beam is left unillurninated and blank so that said laser aiming beam propagates in a ring configuration in both the unscanned and scanned beam propagation modes, said rifle, gun and missile launcher sights being aligned so that the fired bullet or projectile, propagates within the dark central area of the ring aiming beam to target, Trget range may be estimated by focussing the rin' output, either manually or electro-optically, onto target.

15 The invention has application in police work, in terrorist counter attacks, in the defence fields as a means of precision imaging a potential target, setting the trajectory of a missile to said target and monitoring the effectiveness of the aimed shot to target. The invention has the capability of operating day or night, in good and bad weather and the operator's aiming and target identification can be viewed and approve or over-ruled at a remote base site.

SUMMARY OF THE PRIOR ART Prior art laser rifle sights have utilized a laser beam whose intensity is maximum at its centre and reducing towards its circurnference. Prior art laser fifle sights have been stand alone I lcll-- i I systems with no means of the rifleman being over-ruled once his target had been sighted because the said rifleman alone, usually under conditions of extreme stress, had the sole responsibility of pulling the trigger once the laser spot was illuminating, for example a dangerous terrorist who would shoot on sight. Prior art laser sighted rifles also siffered from a serious defect in that the aiming beam, generated by a visible laser, for example, a helium neon laser, was emitted with a diameter of about one millimeter and power of one to several milliwatts. Visible beams of this configuration are excessivly scattered by the atmosphere so that a sniper could easily locate the position of the rifleman from the scattered beam light and could, therefore, effectively counter an attack, killing or severely injuring the said rifleman.

Prior art laser sighted rifles also suffered from the 15 fact that the rifleman had to actually see an outline of his target r~before he could actually position the laser spot on it and pull the trigger, In other words, prior art laser rifle sights relied entirely on the human eye to locate the target and determine its outline before the laser rifle aiming beam could be positioned on said target.

The present invention overcomes the defects and problems associated with prior art laser rifle sights. Firstly, the aiming beam is propagated with a ring cross-section of relatively large diameter so that it becomes difficult for the eye of an off angle observer to see any scattered light and hence locate the source of said aiming beam. Secondly, the ring configuration of the aiming i beam lends itself for conical beam scanning and automatic target enhancement. Thirdly, the enhanced target image can be displayed at a remote site so that the lone rifleman does not have to make independent decisions of whether or not to fire the laser sighted rifle, such a decision can be made collectively by a group of officers viewing the exact scene seen by the lone rifleman through his sights on a visual display unit at a remote site. Fourthly, it is a simple matter to align a bright ring of laser light around the most vulnerable or effective portion of a target than it is to align a brightly illuminated spot which could well cover a significant portion of the target at moderate distances. Fifthly, the fact that the invention has the capability of conically scanning the said laser aiming beam means that the actual trajectory of the fired bullet or missile can be recorded together with the accuracy 15 with which the aiming was undertaken so that rapid corrections may be made for the subsequent shot.

In particular, on the one hand the invention can provide 'Is' t a lone rifleman with a safe and accurate laser rifle aiming system, whilst on the other hand the invention can transfer the responsibility to a team of observers and overall controllers at a remote site who 4 can view the target or targets as seen by one or several of the said riflemen and determine the best course of action regarding a particular rifleman.

BACKGROUND OF THE INVENTION The inventors have considerable experience in the laser and related electro-optics business and have been associated with the

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t #4 4 4 44 4* S44 444 0 development of the laser over many years. Regarding the laser rifle sight of this invention the real problem of a police special squad rifleman with a laser sighted rifle exposing himself to counter attack by a sniper due to the scattered laser beam signature, provided investigations of means to reduce this signature and to laser art optical detection techniques which would both enhance the target identification and increase the difficulty of detecting the source laser beams by snipers. Another goal was to display the scene viewed by the lone rifleman at a remote site where the decision to fire and the effectiveness of a particular shot or group of shots could more effectively be determined. It was also believed that it was a simpler task to aim a rifle with the key area of the target within a ring of light rather than a target illuminated by a spot of light whose maximum intensity is at the centre of said 15 laser spot.

Prior art laser rifle sights have utilized helium-neon-laser beams whose visible wavelength is 632.8 nanometers. Visible wavelengths, although they aid the naked eye aiming process, are extremely dangerous from the viewpoint of snipers being able to follow the scattered beam path back to the rifleman and eliminating him.

The use of infra-red laser aiming beams of prior art systems were severely restricted, firstly due to the fact that the naked eye is not able to detect wavelengths beyond about 700 nanometers This meant that if the compact, efficient solid state semiconductor laser was to be used, then even neglecting the complication of the collimating optics, the laser beam had to be viewed with infra-red 44 4 4 t *4 9 4 4 4 1 *i i -ri viewers which in prior art format was cumbersome to say the least.

On the other hand, the use of infra-red emitting neodymium doped yttrium aluminium garnet crystals posed safety problems, particularly those associated with the eyes of the riflemen themselves. The matter is eased with the use of yttrium doped laser crystals emitting at 1,500 nanometers which, in turn, aggravates the infra-red detection problems because of the dramatic fall in optical detector quantum efficiencies beyond 1,000 nanometers. The present invention provides a superior aiming graticule for laser sighted rifles due to the ring nature of the aiming beam. To simplify the aiming graticule further, more than a single ring graticule can be used even with a central spot. The multiple ring aiming beam system is inherently simple to generate when we operate the ring output beam in a conically scanned mode. Such a conically scanned aiming beam can provide a high S 15 resolution image of the target using circularly symmetrical optical detector arrays, for example in the form of image converter/intensifiers and charge coupled detectors which can transform the detected scanned infra-red images into high quality visual images which can r~ot only be viewed and assessed by the lone rifleman, but by a group of task directors at a remote site, relieving the lone rifleman of the 4,41ultimate decision to fire his rifle. The techniques used for scanning laser beams are normally difficult to implement in practice and power hungry. One scanning technique of interest is that of scanning arrays of laser diodes deposited on silicon chips. There are many ways of scanning such phased-locked lavr diode arrays. However, the one of interest here is to switch such arrays so that their r 06

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output form concentric rings of light in a pattern corresponding to what is referred to as Fresnel zones. It is well known that Fresnel zones can act as lenses to focus light beams and the focal length depends on the characteristics of the Fresnel zone pattern. In this invention, a dynamic Fresnel zone pattern emission profile on a phased array of solid state lasers deposited on a silicon chip t provides a very effective beam scanning mechanism and one which can have the laser beam propagating, with a blank central portion, as a series of concentric rings of decreasing widths to the circumference of said beam. Conical scanning of the laser beam allows the target to be imaged electro-optically with high resolution and displayed not only in the rifle sight as a visible image via an infra-red to visible converter, but also distributed via metallic, optical fibre or even atmospheric transmission to a central, remotely sited command post where the rifleman can be relieved of his responsibility for firing the rifle, in fact all he then has to do is aim and hold his rifle steady on target. Scanning the laser aiming beam also reduces the atmospheric backscatter whilst allowing for high target definition.

In fact a combination of a ring aiming beam and a scanning target beam provide a very effective combination in that the target is well outlined overall whilst the ring defines the exact area of target that the bullet will hit.

The use of infra-red laser beams overcomes the detrimental effects of visible beam scattering indicating the source to a sniper which is then able to eliminate the rifleman. To locate t[e source of an infra-red laser aiming beam via atmospheric scattering one has 07 LIe -ii i i r 1 I 1 tootr 4400 ot 14 1 I Ir I II t 'r *o 4 B I *1 0 40 0 1 0* to use indirect techniques based on infra-red viewers which severely limits the response of any sniper under stressful operations.

The format of the invention incorporating remote site control of one or more riflemen implies that the sophisticated but bulky image processing, recording and visual display units are arl remotely sited, only the compact, portable laser beam generator and sensitive optical detectors are actually mounted onto and possibly inside the rifle itself, converting it into a highly sophisticated firearm.

10 The use of semiconductor laser arrays on silicon chips is a recent development compared to the semiconductor laser diode itself which appeared in the early 1960's, Initial models of laser diode arrays suffered by having too few diodes, less than 100, in the array to make phase-locking a realistic proposition. However, computer simulation studies indicated as the number of laser diodes in arrays increases to many thousands, the output beam quality improves and single lobe and more complex operational excitation patterns become more realistic. Ideally, the laser diode arrays for this invention should be between one and two centimetres in diameter and operated at relatively low power levels per diode so that the total output power is a few tens of milliwatts to a few hundreds of milliwatts in a laser aiming beam which does not illuminate the human eye with more power than allowed by international safety standards, that is a few milliwatts per cross-sectional area of 7 millimeters diameter, Even if one were to kill an opponent with a bullet from a laser sighted rifle, it is still considered to be

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Itl.l tl t I SI I It *i I o* *9 unethical to 'lind him first with a laser beam.

Where it is necessary to determine the range of the target the rifleman can either adjust the beam so that it converges on target into a single spot or in the more sophisticated, scanning beam system form of the invention allow this process to be accomplished automatically via the electro-optic scanning, detection and signal processing facilities that are available.

Under adverse weather conditions, the scattering of the beam will be enhanced but this will not help the sniper problem to any significant degree because the scattered ring beam will also be scattered en route to said sniper so the amount of scattered light said sniper can detect is significantly reduced. However, laser radar techniques have been developed which allow target image enhancement through gating the amount of light the rifleman accepts from the target. Such gating of the target reflectance are accomplished electro-optically and by accepting into his detection system, ay reflections and optical scatter noise within 10 meters of said target, all other scatter noise is automatically eliminated.

Naturally, the overall operating range of the laser aimed rifle is diminished in adverse weather conditions, nevertheless, electro-optic gating of the optical noise enhances target imaging.

When the target is moving relative to the rifleman he sees it moving against a static background which could cause problems if the darkened centre portion of the aiming beam traversed a bright light or the contrast between said moving target and the static background was low. Under those circumstances, it is possible to I i~ if i remove the image of the background and just leave the image of the said moving target via the electro-optic image processing facilities of the said invention. In this way the moving target can be allowed to enter the aiming ring and the rifle set to fire automatically when said target is symmetrically positioned within said aiming light ring.

It should also be pointed out that in the scanning hollow beam format, the scanned beam could be generated by an array of incoherent light emitting semiconductor light sources, whilst the aiming ring beam can be generated via a semiconductor laser diode 11 array, that is the said aiming beam is coherent whilht the scanning beam is incoherent. In this case, the aiming beam need only be switched on when the target has been located and adequately imaged in the laser rifle sight.

A problem exists if the hunted target directs a light beam of the same wavelength as the aiming laser beam back'towards the rifleman to saturate his detector system including his naked eye, However, although the detector will be momentarily blinded, the logarithmic amplifier techniques used to minimise such problems protect the detector circuits. On the other hand, the mere fact that a torrorist could direct such a beam back towards the rifleman implies that he is already within the aiming ring and can easily be deactivated by svid rifleman before any chance exists of said terrorist responding in such a sophisticated manner.

When using the system during daylight hours, the target will be clearly visible in an unfiltered, or doubly filtered laser rifle sight, one pass band for the scene, one pass band for the aiming ring of light. However, if the background light is too bright in the unfiltered laser rifle sight then it becomes difficult if not impossible to see the aiming ring. In general the ring of laser light allows for precision filtering of the light in the laser rifle sight so that even under bright sunlight, it is possible to see the aiming beam particularly if the narrow band laser light is modulated relative to the static sunlight of the background optical noise. In other words, if the laser sighted rifle has to be used under bright sunlight conditions for the sake of precision firing: then this can be done. Similarly, the invention with the optical flood lighting of the target, can also be used on a pitch black night. The most appropriate period to use the less sophisticated version of the invention is when there is just sufficient ambient 15 light to outline the target but not too much to swanmp the sighting r I of the laser aiming ring on said target.

One of the major safety requirements for laser sighted rifles is the minimisation of the atmospheric scattering of the aiming beam because such scattered light can allow a sniper to locate the source of the laser beam and hence the rifleman.

One of us (John Leonard Hughes) has had extensive experience in the study of laser beam scattering by the atmosphere. The early pulsed laser radar systems used ruby as the laser medium which emitted a pulse of extremely intense red light at a wavelength of 694.3 nanometers. During the 1960s and early 1970's, ruby laser transmitters were first used by one of us (John Leonard Hughes) on the Lark Hill ii I proof range on Salisbury Plains in Southern England and the Rayleigh scattering off the atmosphere was highly visible during twilight and night operations as viewed from source to target over several kilometers. In fact this backscatter caused major problems with the saturation of the highly sensitive optical detector electronics until the advent of logarithmic amplifiers in said detectors. When more sophisticated laser radar systems were developed for satellite 4$tt and lunar ranging during the late 1960's, the backscattered light ftl from ruby laser pulses being transmitted through the atmosphere were actually used to centre the transmitted laser pulses on the satellites during the tracking operation.

It was not until the late 1970's that this laser radar experience gathered well away from public places was enhanced by 1k t i observation of the scattering properties of high power, continuous 15 wave argon ion lasers propagating overhead along the densely populated Oxford Street in central London as part of the festival season. Looking towards the source of these powerfui continuous wave argon lasers, from halfway down Oxford Street made it difficult to locate which window they emerged from in buildings down one end of the stret despite the fact that the forward scattering was more intense than the backscatter observed when looking down the other way and observing the beams as they propagated away from the observer. However, there is no doubt that the forward scattered light allowed one to approximately locate their source very quickly bearing in mind that these laser Leams were propagating about meters above street level, ~i -u t 4

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4 #4 In the case of the laser beam aimed rifle the situation is different in that the target being illuninated is very close to the beam and despite the fact that such beams are up to 20,000 times weaker than those used in central London for display purposes, they can be problematical particularly if the weather conditions slightly enhance the scattering.

To reduce atmospheric scattering as determined by the naked eye, one has to reduce the intensity of the laser aiming beam without reducing the total light that can illuminate the target. In this invention, this is achieved by propagating the laser light in a ring configuration so that beam intensity is considerably reduced.

Tests utdertaken on behalf of the applicants at The Australian National University in Canberra, showed that no detectable scattering could be generated over a 200 meter long test range using the invention.

OBJECTS OF THE INVENTION It is an object of the invention to provide a laser rifle aiming beam in the form of a ring of laser light allowing for the precision positioning of said target within said ring of laser light, 2C the bullet fired from said laser rifle propagating so as to strike any target which has been positioned within said ring of laser light.

Another object of the invention is to propagate the aiming laser light ring with adequate ring diameter to minimise the amount of atmospheric forward scattered, side scattered and back scattered 'ight from said laser ring which can be sensed by a sniper to direct his aim back to the rifleman using said laser ring beam aiming device 13 of the invention.

It is also an object of the invention to have a means of adjusting the convergence of said laser aiming ring beam so that the distance of a target can be estimated either manually or automatically.

Yet aniuther object of the invention is to provide means of scanning said laser aiming beam, for example, in a connical format allowing for image enhancement, image identification, 'lock-ons and automatic firing.

Another object of the invention is to allow the image of

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a target as observed through the laser rifle sight to be displayed at a remote site either alone or in combination with other laser rifle detector images gathered off the target from diffent locations so that a control team can take over the responsibility of firing the said laser sighted rifles relieving the rifleman of the responsibility in such a stressed operational responsibility, the remote sit recording facilities, record'ing all of the action and decision making processes.

S' BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be obtained from the following considerations taken in conjunction with the figures *which are not meant to limit the scope of the invention in any way.

Figure 1 shows the invention mounted inside the body of a rifle.

Figure 2 shows a multi-mirror arrangement used to generate the ring laser aiming beam after it has been focussed by a lens through a field stop.

h 14. 1- Figure 3 shows a multi-lens arrangement with a blocked central portion used to generate the ring structure of the aiming beam. Although such a strucure introduces severe diffraction ring structures into the transmitted beam the human eye sees an excellent ring of light as the laser beam illuminates the target.

Figure 4 shows the invention in a more sophisticated electro-optic format with the laser beam being made co-axially with the detector system, said laser beam b'ing preferably generated in a doughnut TEM 01 mode or in a ring pattern from a lase.

diode array arld said detector system being in the form of an image intensifier unit when the aiming beam has a visible wavelength and in the form of an image wavelength converter for the infra-red to the visible and an imaga intensifier all combined into a single unit when the aiming beam is invisible to the naked eye.

15 Figure 5 shows the invention with several laser sighted rifles at different locations, the target image from each being displayed on respective television monitors in a remote site control t 1 room with the overall control of firing from any one or all of the said laser rifles coming from said remote site control room thus relieving individual riflemen of the critical decision making processes under extremely stressful conditions.

Figure 6 shows a two task format of a laser transmitting array with the main aiming beam coming from a given section of the array whilst the scanning portion comes from the outer portion of said array.

Figure 7 shows both the aiming and scanning beams being

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generated in a single laser array.

Figure 8 shows the laser beam generator, emitting a 'doughnut" TEM 01 beam which is then split into an aiming and scanning beam via appropriate optical elements prior to transmission.

Figure 9 shows the invention used as a bullet trajectory recorder, recording all the aiming processes, the firing sequence tf and the position that the fired bullet hits or misses the said fil target or portion thereof.

Figures 10 and 11 show the invention used in a format which records the target profile then 1Fires the rifle automatically when the same target appears within the aiming ring of laser light, said device also being able to distinguish a moving target from its static background.

DETAILED DESCRIPTION OF THE DRAIWINGS In Figure 1, numeral 1 indicates the hollowed butt of the laser sighted rifle, numeral 2 the laser beam generator emitting a I doughnut TEMo 1 mode laser aiming beam, numeral 3 the power supply lead to the power supply indicated by numeral 4. Numeral 5 indicates the rechargeable battery pack to drive 4, both 4 and 5 being located in a chamber indicated by numeral 6 in the butt 1 of the rifle.

Numeral 7 indicates a panel with an on/off switch and the jack for inserting the recharging lead for 5. Numeral 8 indicates the rifle barrel whilst numeral 9 indicates the rifle sight of prior art.

Numeral 10 indicates the doughnut profiled laser aiming beam of the present invention.

In Figure 2 numeral 11 indicates a laser beam generator 16 operating in the TEMOO mode with a continuous intensity gaussian profile across the said beam. Numeral 12 indicates a lens used to focus beam 11 through a field stop indicated by numeral 13 before said beam diverges on to the secondary, convex mirror indicated by numeral 14 which diverges a doughnut shaped laser beam onto the concave ring mirror indicated by numeral 15 which collimates the transmitted ring beam whose outer surface is indicated by numeral o~er 17 and its inner surface by numeral 16. Numeral 18 indicates a distant cross-over point which can be varied by adjusting the relativepositions of 14 and Figure 3 shows the gaussian intensity profiled laser beam 11 being diverged by the lens indicated by numeral 19 as the beam indicated by numeral 20 which in turn is collimated by lens indicated by numeral 22 which has its central portion blocked as indicated by numeral 21. The doughnut output aiming beam has its outer surface indicated by numerals 16 and numeral 17 indicates its inner surface.

Again the variable cross-over point is indicated by numeral 18.

g Figure 4 shows the invention incorporating an image wavelength converter/intensifier indicated by numeral 23 mounted on rifle barrel 8. The laser beam generator indicated by numeral 24 has its output beam superimposed on beam paths 11 via the partial beam reflectors indicated by numerals 25 and 26 respectively. The eye of the rifleman indicated by numeral 2' can then see the image of the target (not shown) via 23 irrespective of whether beam generator 24 emits a visible, infra-red or ultra-violet laser beam. The whole laser sight is enclosed in the module indicated by numeral 28.

17 I: Figure 5 shows the target indicated by numeral 29 sighted simultaneously by three riflemen indicated by numerals 20, 31 and 32 respectively. Image information from electro-optical device 23 (Figure 4) is transmitted along co-axial or optical fibre cables 33, 34 and 35 respectively to the image processing module indicated by numeral 36 which is located at a remote site control room where a control team view the target 29 on three monitors indicated by numeral 37. In this manner, the overall operation is fully controlled from said remote monitors 37 relieving the individual riflemen of the critical decision making process in such a stressful environment.

Figure 6 shows the laser beam generator of the invention in the form of a switchable, phased-array of laser diodes deposited on a silicon chip indicated by numeral 38. Numeral 39 indicates the surface of the scannable output beam of said phased-array diode laser array which is either linearly or conically scanned to obtain a hir" definition image of the target and its background and to provide image processing capabilities so as to separate a moving target from its static background. Numeral 40 indicates the high intensity emission areas from said diode laser array which allows F for the generation of the ring aiming beam to pin-point the target. Numeral 41 indicates the input to 38 from a micro-computer controlled power supply (not shown) which switch the laser diode in the said phased-locked diode laser array so as to produce the necessary outp-t patterns covered by 39 and Figure 7 shows a phased-locked diode array indicated by 18 numeral 42 where all the said diodes emit equal amount of laser light when switched via 41, but with the scanning pattern of beam 39 being such that the scanning motion indicated by numeral 43 actually produces the ring aiming beam 40 by said beam 39 spending more time in that particular area of the beam output on target.

Figure 8 shows the laser beam generator 11 emitting a doughnut aiming beam 40 which rings the target (not shown). However, a portion of the said doughnut beam emitted by 11 is split off via I a beamsplitter indicated by numeral 44 which can have a hole in its central portion. Said-split off doughnut beam is eventually superimposed on static beam 40 in the form of a conically scannable beam indicated by numeral 46 which is scanned via a hollow, cylinarical scanner indicated by numeral 45 driven via the outside cylindrical electrode indicated by numeral 47 and the central rod electrode indicated by numeral 48 which is passed through the aperture in a V beam splitter 44 so as not to interfere with the doughnut beam inputed into said scanner.

In Figure 9 we show the portion of a bullet's trajectory within a scanned ring aiming beam 46. Numeral 49 indicates the said bullet fired towards a target (not shown) along its trajectory indicated by numeral 50. As the bullet 49 travels to target along beam 46 oscillates as 43 engulfing said bullet en route and causing a reflected signal to be detected at the rifle sight. In this way, the scannable beams can be used to determine the exact position that the bullet will hit the target.

Figure 10 shows the form of the invention where a stored k image of the target indicated by numeral 51 is displayed whilst the real target indicated by numeral 52 moves towards it. In Figure 11, both the stored image of the target 51 and the real image 52 are superimposed and the rifle fired. This format of the invention is particularly useful under conditions of intense activity where the rifleman has not time to steady his rifle and his aiming ring passes along very briefly across his target.

The invention has application for the aiming of large guns where the trajectory of the shell may differ greatly from the line of sight projection of the aiming ring. The invention can also be used with anti-aircraft guns and missile launchers.

Modifications may be made to the invention as uescribed herein without departing from the spirit and scope of the invention.

To this extent it is pointed out that the invention is to be given a broad connotation and is not to be restricted to the embodiments specifically described.

Claims (8)

1. A system for laser beam sighting and target identification using a hand-held rifle Gor h-ad- .hld fljgi gun or missile launcher, consisting of a laser beam generator and a laser power supply all mounted on said rifle or attached to the said gun or the said missile launcher the laser beam generator emitting an aiming beam in such a manner that the central portion of the aiming beam is left unilliuminated so that said aiming beam propagates in a ring configuration, said rifle, gun or missile launcher sights being aligned so that a fired bullet or projectile, propagates within the dark central portion of the ring aiming beam to a target.

2. A system as claimed in claim 1 where the aiming beam has a doughnut intensity profile which is generated as a TEMoi mode within the said laser beam generator.

3. A system as claimed in claim 1 where the aiming beam is first generated as a laser beam of continuous intensity cross-section but then converted Into a ring of laser light by a telescope consisting of a small central convex mirror and a larger concave annular mirror set in a Cassigrain configuration.

4. A system as claimed in claim 1 where the laser aiming beam is first generated with a continous intensity cross-section then converted into a ring of laser light via a lens telescope with the central region of the output lenses blocked to laser beam transmission, A system as described in ciariin 1 where the mean diameter of the aiming ring of laser light is such as to minimise detectable scattering of said aiming beam by the atmosphere, "j thus making it more difficult to locate said laser beam generator via said scattered light.

6. A system as claimed in claim 1 where the laser beam is split into two parts, one projecting the aiming ring onto target whilst the other portion of said beam is used to scan said target to provide a high resolution image which can be processed and recorded at a site remote from the rifle man via a co-axial cable, fiber optic or atmospheric communication iin0. 21 J- 4 5

7. A system as claimed in claim 6 where the high resolution image can be displayed at a remote site control centre alongside similar images of the sighted as viewed from different locations, the overall command of the firing sequence can e issued from said remote site,

8. A system as claimed in claim 6 with alaser aiming beam and target scanniing beam generated in a switchable phased array of laser diodes said output being composed of an intense annular aiming beam surrounded by a conically scanned target imaging beam. S 9. A system as claimed in claim 1 where the laser beam is generated in the format of a Fresnal zone plate by a switchable, phased locked, scannable array of laser diodes, the scan pattern of the output beam of said array being itensified in time into an annular aim'ng beam and a conically scanned target imaging beam, said system allowing for both bullet trajectory monitoring and image identification. A system as described in claim 1 where a portion of the aiming beam is split off, passed through a conical scanner then superimposed on said aiming beam to provide a I conically scanned image enhancement beam.

11. A system as claimed in claim 1 substantially as hereinbefore described and illustrated with respect to the drawings. S MO3NARO RESEARCH LABORATORIES PTY LTD DATED THIS TENTH DAY OF JANUARY 1990 -4