Abstract:
An infrared laser landing marker system provides a capability to mark a boundary line of varying lengths with near infrared lasers, e.g., of the order 8xx nm. This system can be either directly operated or remotely operated via satellite communications and is compatible with currently fielded night vision goggles. Two modules, placed at either end of boundary, self align to each other and then proceed to mark a boundary edge of a landing zone with an infrared laser line.

Description:
GOVERNMENT INTEREST 
       [0001]    The invention described herein may be manufactured, used, sold, imported, and/or licensed by or for the Government of the United States of America. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to illumination systems for military aircraft, and more particularly to infrared laser landing markers. 
       BACKGROUND OF THE INVENTION 
       [0003]    The typical method of marking a temporary boundary or landing zone is through the use of beacons that are arranged around a safe landing area, or by marking the area with hand held, high powered lasers. These methods require personnel to be on the ground and in the vicinity of the landing area in order to place and operate the markers. Requiring ground operators to be present also limits safety, efficiency and jeopardizes the success of the operation. When lasers are used to mark the boundaries of the area, they are often hand operated and rely on the skill and accuracy of the operator. 
       SUMMARY OF THE INVENTION 
       [0004]    An exemplary Infrared Laser Landing Marker is comprised of two modules placed at opposite ends of a landing zone. Each module has the capability of detecting and aligning to the opposing module, and to scan a laser line on the ground out to the opposing module creating a solid line along one edge of a landing zone. These modules can be adjusted to be used on landing zones of varying length. 
         [0005]    In one aspect, an exemplary infrared laser landing marker system comprises placing two opposing infrared laser landing marker modules at opposite ends of a predetermined area to mark a landing zone, each said module being mounted to a platform or a tripod and stationed at each respective end along a boundary edge of said landing zone; said two opposing modules being oriented facing each other with a horizontal tolerance of about 20 degrees, respectively; activating the modules to emit an alignment laser for the opposing module to align to; detecting and aligning with the respective opposing module by each of the modules for alignment; and disabling the respective alignment laser upon completion of said alignment and generating a near infrared line generating laser about half the distance of the landing zone, creating one continuous boundary line spanning the length of the landing zone. 
         [0006]    In another aspect, an infrared laser landing marker module capable of detecting an opposing module beacon for self alignment comprises an alignment laser to function as a point source beacon for the opposing module to detect for self alignment; a quad photo-detecting sensor having four quadrants to detect an alignment laser from said opposing module, the four quadrants of the sensor capable of enabling compare and determine for alignment to said opposing module; a line generating laser for activation upon completion of alignment; a processor and electronics board for computations to determine the needed adjust alignment; and a pan motor and a tilt stepper motor for adjustment of azimuth and elevation of the module. 
         [0007]    Yet, in another aspect, an exemplary infrared laser landing marker operating method comprises placing one infrared laser landing marker module at one end and another module at another end of a landing zone to define the length of a landing strip; disposing the modules to oppose each other within a 20 degree horizontal tolerance; activating the infrared laser landing marker by powering the respective module; selecting a runway distance setting to closely approximate the landing strip length of the landing zone; activating an alignment laser for each module to alignment with respect to the opposing module; and activating a line generator. 
         [0008]    As variously disclosed, greater accuracy in marking a boundary edge of a landing zone can be achieved, including the ability for long term pre-placement and remote operation. The ability of the modules to self-align to each other reduces risk and the time it takes to correctly place the modules. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Additional advantages and features will become apparent as the subject invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0010]      FIG. 1  shows an exemplary module of an infrared laser landing marker (IRLLM); 
           [0011]      FIG. 2   a  shows a top view of an exemplary infrared laser landing marker (IRLLM) system in operation; 
           [0012]      FIG. 2   b  shows a side view of an exemplary infrared laser landing marker (IRLLM) system in operation; and 
           [0013]      FIG. 3  shows an exemplary process flowchart of an infrared laser landing marker (IRLLM) operation. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Apparatus: There are several components that are integrated together in one IRLLM module that include mechanical, electrical and optical parts.  FIG. 1  shows an exemplary module of an infrared laser landing marker (IRLLM)  100  with the major components that make up such an exemplary IRLLM Module. The capability to detect an opposing module is disclosed for the ability of self alignment. To accomplish self alignment, the alignment laser  110  is used to act as a point source beacon for another module to detect. This laser is detected by a quad photo-detecting sensor  120 . The four quadrants (e.g.,  121 - 124 ) of the sensor  120  act as, or enable, comparators to determine alignment to the opposing module. Differences in signal strength across the sensor  120  determine the directions the module must move in order to self align. The calculations to determine how much to adjust alignment is performed by the processor and electronics board  130 . The azimuth and elevation of the module  100  is adjusted by one pan  140  and one tilt stepper  150  motor. This process is repeated until the module  100  is completely aligned. Once alignment is accomplished, the module  100  will deactivate the alignment laser  110  and activate the line generating laser  160 . The battery chamber  170  supplies power to the sensor  120 , motors (e.g.,  140 ,  150 ), electronics and lasers (e.g.,  110 ,  120 ,  130 ) to enable the modules usage in remote locations that are without electricity. User controls (e.g.,  180 ) are located on the back of the module  100  enabling a user to activate and deactivate the module  100  physically or remotely if the module has been pre-placed prior to a landing operation. 
         [0015]    System: As variously shown in  FIGS. 2   a  and  2   b , the IRLLM (Infrared Laser Landing Marker) is a self aligning, covert marker for temporary and ad-hoc landing zones. One IRLLM module is comprised of electrical, optical and mechanical components as described in  FIG. 1 ; there are two such modules  200   a  and  200   b  per one IRLLM system  200 . Each module is mounted to a tripod ( 280   a  and  280   b ), but can be mounted to other stable platforms as well. 
         [0016]      FIG. 2   a  shows atop view of an exemplary infrared laser landing marker (IRLLM) system  200  in operation. On a predetermined area for landing, one IRLLM module ( 200   a  or  200   b ) is stationed at each end along a boundary edge of a landing zone. The two modules ( 200   a  &amp;  200   b ) must be oriented facing each other with a horizontal tolerance (Ta and Tb) of 20 degrees, respectively. When activated, each module ( 200   a  or  200   b ) emits an alignment laser ( 211   a  or  211   b ) for the opposing module to align to. 
         [0017]      FIG. 2   b  shows a side view of such an exemplary IRLLM system in operation. Once said alignment is complete, the respective alignment lasers  211   a  and  211   b  are disabled and each module ( 200   a  and  200   b ) will generate a near infrared line generating laser ( 261   a  and  261   b ) about half the distance of the landing zone, creating one continuous boundary line  261  (a composite of  261   a  and  261   b ) spanning the length of the landing zone (e.g.,  230 ). This line spanning the landing zone (e.g., landing strip  230 ) is visible only to detectors sensitive to wavelengths in the range of about 800-899 nm, such as night vision goggles. 
         [0018]    Method:  FIG. 3  shows an exemplary infrared laser landing marker (IRLLM) flowchart. Referring to  FIG. 3 , such a method  300  uses an Infrared Laser Landing Marker, e.g.,  100 ,  200   a  or  200   b  as described with respect to  FIGS. 1 and 2 . Starting with step  310 , an operator can place the system  200  with one module  200   a  at one end and another module  200   b  at another end of a landing zone to define the length of a landing strip  230 . They are disposed facing each other within a 20 degree horizontal tolerance (Ta, Tb). Once placed, in step  320 , the user activates the system  200  by toggling the power ON of the respective module ( 200   a  and  200   b ), either physically on the system or remotely via communications. After powering on the system, in step  330 , runway distance is selected, e.g., to the setting closest to the actual landing strip length  230  of the landing zone. In step  340 , pressing the alignment switch will activate the alignment laser (e.g.,  110  of  FIG. 1 ) for each module (e.g.,  200   a  or  200   b  of  FIG. 2 ) to self-align to one another as depicted in step  350 . 
         [0019]    After the alignment of step  350  is accomplished, the line generator is activated. The activation of line generator as depicted in step  360  scans a near infrared laser line, e.g., along one boundary edge of a designated landing zone (e.g.,  230 ). As shown in branch  341  leading to the reset portion of step  370 , the user has the option to reset the system if alignment fails or if he wants to realign the system. For example, further shown leading out of step  370  is a yes branch  371  leading back to step  340  for pressing the alignment switch. Once an operation (e.g., of the line generator activation branch of  361 ) is completed, the user will toggle the power off as shown in step  380  to deactivate the IRLLM system. 
         [0020]    It is obvious that many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as described.