Abstract:
The laser aiming system for projecting a X-shaped aiming beam along an aiming axis, has a first and second laser modules which are adapted to project a first and second planar fanned beams along a first and second axes of projection respectively. The first and second axes of projection extend parallel with, and spaced-apart from each other and from the aiming axis. The first and second planar fanned beams are skewed about the first and second axes of projection respectively, intersecting each other on the aiming axis and forming a X-shaped aiming beam having different supplementary angles.

Description:
This is a continuation-in-part application of application Ser. No. 11/797,667, filed May 7, 2007, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention pertains to projections of laser aiming beams, and more particularly it pertains to the projection of a X-shaped aiming laser beam toward a target. 
     BACKGROUND OF THE INVENTION 
     In order to characterize the present invention over the prior art, reference is made to systems found in the prior art for projecting a laser beam toward a target. Three examples are briefly described below. 
     U.S. Pat. No. 5,118,186 issued to J. Schrätzenstaller et al. on Jun. 2, 1992. This document discloses a sighting system for weapons wherein a single spot is projected toward a target. 
     US Patent Application 2003/0180692 filed by J. A. Skala et al. on Mar. 22, 2002. This document discloses an aim point tracking system, wherein the aiming mark projected is a crosshair made of two laser lines, extending horizontally and vertically respectively. 
     US Patent Application 2005/0278964 filed by S. Minica et al. on Jun. 17, 2004. This document discloses a laser targeting system mounted on an arrow point and projecting on a target, a dot where the arrow will hit once released. 
     Although the aiming systems of the prior art deserve undeniable merits, there is a need for an aiming system capable of projecting aiming beams generating a X-shaped mark on a target as opposed to a spot or a crosshair. 
     A spot mark is difficult to maintain in position on a colourful target, on a moving target, on a target partly hidden by camouflage material or on an object having numerous visual details thereon. Similarly, a crosshair is sometime difficult to adjust and to see on an object having a rounded shape such as a cylinder or a sphere or on an object having horizontal or vertical features, such as a building, a briefcase or other boxlike package. 
     It is believed that a need exists for an laser-projected aiming mark having the shape of a X. Even if such a X-shaped mark is only partly seen on a target, one can easily determine where the center of the mark is located, which make is much easier to adjust the mark to the target. 
     In the present context, a X-shaped mark is made of two lines intersecting each other and making different supplementary angles there between the lines. Preferably, neither line is perfectly horizontal or perfectly vertical. 
     In another aspect of aiming devices, the laser aiming systems of the prior art are aligned to an expected hit spot of a shot fired from a known distance. If that distance changes, the laser mark is no longer reliable. Therefore, there is a need for a laser aiming system that is relatively true regardless of the distance between the shooter and the target. 
     SUMMARY OF THE INVENTION 
     In the present invention, however, there is provided a method and a system for projecting a X-shaped aiming mark on a target. The X-shaped mark is made of two lines which intersect each other with different supplementary angles. Each line is the projection of a planar fanned laser beam. 
     More particularly, in a first aspect of the present invention, there is provided a laser aiming system for projecting a X-shaped aiming beam along an aiming axis. The laser aiming system has a first and second laser modules which are adapted to project a first and second planar fanned beams along a first and second axes of projection respectively. The first and second axes of projection extend parallel with, and spaced-apart from each other and from the aiming axis. The first and second planar fanned beams are skewed about the first and second axes of projection respectively, intersecting each other on the aiming axis and forming a X-shaped aiming beam having different supplementary angles. 
     The laser aiming system is applicable to firearms, to disrupters used to destroy suspicious packages, to weapons of war, to toys such as laser tag guns, paint-ball guns and to other projectile launchers. The aiming system is easy to calibrate and is true over great distances. 
     In another aspect of the present invention, there is provided a method for calibrating a laser aiming system to an aiming axis, wherein the laser aiming system has two collimated laser modules projecting a first and second planar fanned beams, for generating a X-shaped aiming beam. This method comprises the steps of aligning axes of projection of the laser modules parallel with each other and with the aiming axis; and skewing the planar fanned beams about their respective axes of projection, and forming an intersection of the planar fanned beams on the aiming axis, wherein the intersection is made of lines intersecting at different angles. 
     In yet a further aspect of the method mentioned above, an additional step is provided when each of the fanned beams has an inherent drift therein. This additional step is described as orienting the drifts below the aiming axis. The X-shaped aiming mark is then projected slightly below the aiming axis of the barrel on which the laser aiming system is mounted. The aiming mark is projected below the aiming axis for accounting for a natural drop in the trajectory of the projectile to be launched, and for providing a truer projection of the aiming mark. 
     This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate a preferred embodiment of a laser system for generating a X-shaped laser projection toward a target. 
         FIG. 1  illustrates a system for projecting a X-shaped mark on a target; 
         FIG. 2  illustrates a system for generating a three-arm projection on a target; 
         FIG. 3  illustrates a five-arm mark which can be generated in a similar manner as the mark illustrated in  FIG. 2 ; 
         FIG. 4  illustrates an inherent drift of a projected line in a planar fanned laser beam; 
         FIG. 5  illustrates a preferred positioning of two planar fanned beams each having an inherent drift of their projected lines; 
         FIG. 6  illustrates an emitted and a projected X-shaped mark made by two planar fanned beams having inherent drift in their projected lines. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will be described in details herein one specific embodiment of the present invention, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated and described. 
     The system  10  according to the preferred embodiment for projecting an aiming X-shaped mark on a target is illustrated in  FIG. 1 . The system comprises two laser modules  12 ,  14  mounted on a saddle-like holder  16 . The saddle-like holder  16  is mounted astride on the barrel  18  of a disrupter unit, for example. Although a barrel of a disrupter unit is mentioned herein, the aiming system  10  can also be mounted to the telescope mount or other sight rail mount of a firearm, on a weapon of war, or on a toy gun. 
     Both laser modules  12 ,  14  have collimated light beams projecting planar fanned beams  20 ,  22  respectively. Both laser modules  12 ,  14  have axes of projection  24 ,  26  respectively that are set parallel with each other and parallel with the central axis  28  of the barrel  18  on which they are mounted. Both laser modules  12 ,  14  project lines  30 ,  32  respectively, which extend perpendicular to their respective axes of projection  24 ,  26 . 
     A preferred method for aligning the fanned beams  20 ,  22  to the barrel axis  28  consists of skewing the laser modules  12 ,  14  and the fanned beams  20 ,  22  so that the fanned beams  20 ,  22  intersect each other and the barrel axis  28  along a common line segment  42  passing through intersection point  40 . The X-shaped projection generated by the system carries as far as the power of the laser modules allows it to, and the center  40  thereof remains remarkably true to the axis  28  of the barrel  18  over great distances between the barrel  18  and the target on which the barrel is aimed. 
     The alignment of the fanned beams  20 ,  22  is made by inserting a laser module (not shown) inside the bore of the barrel  18  for example and by skewing the fanned beams  20 ,  22  until they intersect the line generated by the laser-line generator along the axis  28  of the barrel. 
     The barrel axis  28  is also referred to herein as the aiming axis  28 , for convenience. 
     The saddle-like holder  16  is made of spaced apart plates  50  having holes therein to receive both laser modules there through with their axes of projection  24 ,  26  extending in a parallel alignment with each other. The saddle-like holder  16  has stand members  52  capable of holding both laser modules  12 ,  14  to the barrel  18  with the axes of projection  24 ,  26  of the laser modules extending in a parallel alignment with the axis  28  of the barrel  18 . 
     Once calibrated, the laser module assembly can be taken off the barrel  18  and reinstalled as required without calibration. The laser module assembly,  12 ,  14 ,  16  is preferably detachably mounted to the barrel  18  with a strap, a clamp or other fasteners selected by the designer. 
     Although only two laser modules  12 ,  14  have been explained herein above, it will be understood that three or more laser modules can be installed on or near a barrel in a same way as described herein to generate an aiming mark in the shape of a multi-arm projection or mark such as the three-arm projection  30  shown in  FIG. 2 , and the five-arm mark  32  shown in  FIG. 3 , for examples. At least one X-shaped mark can be found in each of these alternative aiming projection  30  and mark  32  and therefore, they should be considered as having been generated using the method according to the present invention. 
     Also, it will be appreciated that a single laser module can be used to generate two fanned beams from a same light source. 
     Referring back to  FIG. 2 , it will be appreciated that the three laser modules  34 ,  36 , and  38  do not have to be a same radial distance from the aiming axis  28 , and they do not have to be at a same position along the aiming axis  28 . When the axes of projection of the laser modules  34 ,  36 , and  38  are parallel with the aiming axis  28 , the method described herein is only limited by the power and collimating accuracy of the laser modules. 
     Although the fanned beams illustrated herein are symmetrical to the axes of projection of the respective laser modules, different collimators can also be used to limit the width of the beams to obtain a X-shaped mark that has symmetrical proportions relative to the aiming axis  28 . The planar fanned laser beams can also be collimated to generate a X-shaped mark that is made of dashed lines, lines of dots, lines of X&#39;s, crosses or O&#39;s or lines made with other graphic symbols. 
     The above description has been written for high quality laser modules, the beams of which do not deviate from their projected paths. In reality, however, a designer cannot always find high quality lasers, and must be contented with laser beams that have a slight inherent drift in their projections. In that perspective, there is illustrated in  FIGS. 2-4 , a method to calibrate two fanned beams each having an inherent drift of their projected lines. The method presented herein take advantage of an inherent drift in a laser beam to enhance the precision of the preferred aiming system. 
       FIG. 4  illustrates a planar laser beam A emitted from an average quality laser module  60  and seen when looking toward its source. Over a large distance, this beam drifts to one side and the projected line ‘A’ is no longer true to the axis of projection of the laser module  60 . When both laser beams A and B in the preferred aiming system have such a drift, the laser modules  60 ,  62 , as illustrated in  FIG. 5 , are placed over a barrel  64  at a same distance above the barrel, and are set such that the direction of the drift is facing away from the axis  66  of the barrel  64 . 
     The laser beams A and B are adjusted as described earlier, to intersect each other and on the axis  66  of the barrel  64  on which the laser modules  60 ,  62  are mounted, as shown in  FIG. 6 . As a result, the X-shaped projection A, B leaves the barrel in a true alignment with the axis of the barrel  66 , and drift down toward the target to a new position  68  which is slightly lower than the axis  66  of the barrel  64 . The amount C of drift of the X-shaped projection A′,B′ corresponds to some extent to an inherent drop of a projectile over its course. Therefore, it will be appreciated that the X-shaped projection A′, B′ on a target is more realistic and more precise than one with no drift at all. 
     If one desires to obtain an aiming mark that takes into account the inherent drop in the trajectory of a projectile, a laser beam drift may be set in the laser modules to obtain the above-mentioned advantageous effect to a desired degree. 
     While one preferred embodiment of the present invention and a preferred method have been illustrated and described herein above, it will be appreciated by those skilled in the art that various modifications, alternate constructions and equivalents may be employed. Therefore, the above description and the illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.