Patent Publication Number: US-9429651-B2

Title: Method of monitoring an area

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of co-pending U.S. application Ser. No. 13/291,668, filed Nov. 8, 2011, which claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/411,261, filed Nov. 8, 2010, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to optical beam steering systems. 
     2. Description of the Related Art 
     Conventional methods for intruder detection include video monitoring, infrared detection and acoustic detection. These methods for intruder detection are human intensive for screening out false alarms. 
     What is needed is a system and method for detecting, classifying, tracking and communicating information for intruders which requires less human intervention for operation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system and method for an intruder network system for detecting, classifying, tracking and communicating information associated with an intruder. 
     In accordance with an aspect of the present invention, a device is provided for detecting a presence of an object. The device includes an optical phased array, a detector, a processing portion and an indicator. The optical phased array can transmit a first optical beam to a first location at a first time and can transmit a second optical beam to a second location at a second time. The detector can detect a first reflected beam based on the first optical beam and can detect a second reflected beam based on the second optical beam. The processing portion can determine the presence of the object based on the first reflected beam and the second reflected beam. The indicator can generate an indicator signal based on the presence of the object. 
     Additional advantages and novel features of the invention are set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of the specification, illustrate at least one exemplary embodiment of the present invention and, taken together with the description, explain the principles of the invention. In the drawings: 
         FIG. 1  is an illustration for an example intruder network system, in accordance with an aspect of the present invention; 
         FIG. 2  illustrates an example node as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 3  is a block diagram for example node as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 4  is an example illustration for the operational modes for the intruder network system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 5  is an example illustration of a graph for the operation of nodes as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 6  is an example illustration of a table for the characteristics and design parameter values for the system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 7  is an example illustration for a beam transmission chart for the system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 8  illustrates intruder detection for the example system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; 
         FIG. 9  illustrates an example system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention; and 
         FIG. 10  illustrates an example method for detecting, classifying, tracking and communicating information associated with an intruder, in accordance with an aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with aspects of the present invention, an intruder network system is presented for detecting, classifying and tracking an intruder via lidar. 
     Lidar is an optical remote sensing technology that can measure the distance to, or other properties of a target or an intruder by illuminating the target with light. Light is often generated using pulses from a laser. Lidar may use ultraviolet, visible or near infrared light in order to receive and process light reflected from surrounding objects and terrain. Light is typically reflected via backscattering. In an example embodiment, an optical phased array may include that which described in U.S. patent application Ser. No. 13/047,379, filed Mar. 14, 2011, titled “System and Method for Using Planar Device to Generate and Steer Light Beam,” to Papadakis et al., the entire disclosure of which is incorporated by reference herein. 
     Furthermore, intruder network system communicates information associated with intruder to other nodes and a control system in order to perform further detection, classification, tracking and communication for the intruder by the other nodes and the control system. 
     Intruder network system provides a lidar sensor network using a flat, optical phase array laser aperture. The network of optical phase array lidars provides automatic collaborative detection, tracking, classifying and acquisition cueing. The network includes a plurality of nodes for performing lidar processing. As a non-limiting example, a node of the system is configured with four optical phased arrays, each with approximately 1 million radiating elements in a 1-cm 2  aperture enabling electronic beam steering. Furthermore, the four arrays are mounted on four sizes of a structural component associated with a node thereby providing a 360 degree field of view. A plurality of nodes provides detection, tracking, classifying and acquisition cueing over a large geographical area. 
     Intruder network system provides a three-dimensional position of objects using a single sensor device. Furthermore, processing by system does not require correlation or estimation algorithms. 
     A plurality of nodes enables collaboration between the node devices for conditions of obstacle blockages and countermeasures such as lidar blinding. 
     Intruder network system may operate in daylight or nighttime conditions, as compared to some conventional systems which only operate in nighttime conditions (e.g. passive infrared). 
     Aspects of the present invention will now be described in detail with reference to  FIGS. 1-10 . 
       FIG. 1  is an illustration for an example intruder network system  100 , in accordance with an aspect of the present invention. 
     Intruder network system  100  includes a node  102 , a node  104  and a node  106  and a control station  108 . 
     Intruder network system  100  performs operations associated with intruder search, detection, classification, tracking and communicating. As a non-limiting example, intruder network system  100  may be used for detecting, classifying and tracking a person trespassing on an entities property and for communicating information associated with a trespassing person. 
     Nodes  102 ,  104  and  106  search for, detect, classify and track intruders and communicate information associated with intruders. Furthermore, nodes  102 ,  104  and  106  search for, detect, classify and track intruders and communicate information optically. 
     Control station  108  communications information bi-directionally with the nodes and presents information received and processed from nodes. 
     Node  102  communicates bi-directionally with node  104  via an optical communication channel  110 . Node  104  communicates bi-directionally with node  106  via an optical communication channel  112 . Node  104  communicates bi-directionally with control station  108  via an optical communication channel  114 . Node  106  communicates bi-directionally with control station  108  via an optical communication channel  116 . 
     In this example, node  102  is not able to communicate directly with node  106  or control station  108  due to an obstruction  118  blocking the line-of-sight between node  106  and control station  108 . Node  102  may communicate with node  106  and/or control station  108  indirectly via communication with node  104 . Nodes  102 ,  104 ,  106  and/or control station  108  may communicate bi-directionally with one another directly and/or indirectly. 
     Intruder network system  100  performs searches for, detects, classifies, tracks and communicates information associated with an intruder  120 . 
     Node  102  transmits a lidar beam  122 . Furthermore, node  102  receives and processes reflections of lidar beam  122 . Node  104  transmits a lidar beam  124 . Furthermore, node  104  receives and processes reflections of lidar beam  124 . Node  106  transmits a lidar beam  126 . Furthermore, node  106  receives and processes reflections of lidar beam  126 . 
     Nodes  102 ,  104  and  106  perform operations associated with intruders by transmitting a plurality of optical beams and receiving and processing reflections of the transmitted optical beams. Furthermore, nodes  102 ,  104  and  106  transmit, receive and process information from the other nodes and control station  108  associated with intruders. 
     As an example of typical operation, node  102  transmits lidar beam  122 , node  104  transmits lidar beam  124  and node  106  transmits lidar beam  126 . Node  102  receives and processes reflections of lidar beam  122 . Node  104  receives and processes reflections of lidar beam  124 . Node  106  receives and processes reflections of lidar beam  126 . Node  106  detects intruder  120 . Node  106  classifies intruder  120 . Node  106  tracks intruder  120 . Node  106  communicates information associated with intruder  120  to node  102 ,  104  and control station  108 . If possible, node  102  searches for, classifies, tracks and communicates information for intruder  120 . If possible, node  104  searches for, classifies, tracks and communicates information for intruder  120 . Node  102  and node  104  communicate information associated with intruder  120  to node  106  and control station  108 . Control station  108  receives and processes information associated with intruder  120  and presents received and processed information for viewing. Furthermore, control station  108  may communicate an alarm or an alert associated with received and processed information associated with intruder  120 . 
       FIG. 1  is an illustration for an example intruder network system where nodes transmit optical beams, receive and process reflected beams, search for, detect, classify, track and communicate information associated with an intruder or intruders. 
     In an example embodiment, node  102  receives and converts light energy to electrical energy for storage, provides electrical power via stored electrical energy, determines location information and time information via a GPS receiver, transmits a shaped beam, receives a reflected beam, processes reflected beam, communicates processed information to external nodes, receives information from external nodes and processes information received from external nodes. This will be described in greater detail with reference to  FIG. 2 . 
       FIG. 2  illustrates an example of node  102  as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Node  102  includes an enclosure  202 , an extendable mast  203  and an optical array cube  204 . 
     Enclosure  202  provides support for and containment of electronic devices. As a non-limiting example, enclosure  202  may be configured in a square shape with a side dimension of approximately 60 centimeters. 
     Extendable mast  203  provides height for electronic devices and as a conduit for communication cables between electronic equipment located in the top of extendable mast  203  and electronic equipment located within enclosure  202 . Extendable mast  203  may be configured for a variety of heights. As a non-limiting example, extendable mast  203  may be configured for approximately 100 centimeters. 
     Enclosure  202  includes a battery portion  206 , a processor portion  208 , a GPS receiver  212 , a receiver portion  214 , a transmitter portion  216  and a solar panel portion  218 . In this example embodiment, receiver portion  214  and transmitter portion  216  are distinct elements. In other embodiments, receiver portion  214  and transmitter portion  216  may be combined as a unitary device. Further, in this example embodiment, GPS receiver  212  and processor portion  208  are distinct elements. However, in other embodiments, GPS receiver  212  and processor portion  208  may be combined as a unitary device. Battery portion  206  receives, stores and provides electrical power. Processor portion  208  provides execution of operational codes and storage/retrieval of information for controlling the operation of node  102 . GPS receiver  212  receives and processes information received via radio waves for determining geographic location with respect to the Earth. Furthermore, GPS receiver  212  provides location and time information for synchronization nodes. Receiver portion  214  may be a dual lidar/communication element, wherein it is operable to receive information optically and by RF. Receiver portion  214  may include a plurality of receiver elements, the combination of which provides a combined ability to communicate with other nodes and to receive optical information from a lidar sweep, as will be described in greater detail later. In an example embodiment, receiver portion  214  receives information optically associated with intruder detection, classification and tracking and receives information from external entities. Transmitter portion  216  may be a dual lidar/communication element, wherein it is operable to transmit information optically and by RF. Transmitter portion  216  may include a plurality of transmitter elements, the combination of which provides a combined ability to communicate with other nodes and to transmit optical information from to create a lidar sweep, as will be described in greater detail later. In an example embodiment, transmitter portion  216  transmits information optically for performing intruder detection, classification and tracking and for communicating with external entities. Solar panel portion  218  receives light energy and converts the light energy to electrical energy. 
     Extendable mast  203  includes an optical fiber portion  224  and an electrical cable portion  226 . Optical fiber portion  224  includes a plurality of optical fibers for bi-directional optical communication. Electrical cable portion  226  includes a plurality of electrical cables for bi-directional communication and for providing electrical power. Optical array cube  204  includes a plurality of optical phased arrays with a sampling noted as an optical phased array  220  and a GPS antenna  222 . 
     Optical phased array  220  performs beam shaping for a lidar beam. GPS antenna  222  receives radio waves from external entities. A non-limiting example of an external entity is a GPS satellite. Optical fiber portion  224  provides a conduit for transmitting and receiving optical beams. Electrical cable portion  226  provides a conduit for transmitting and receiving electrical signals and provides a conduit for transmission of electrical power. 
     Optical phased array  220  includes an optical layer portion  228  and an integrated circuit layer portion  230 . Optical layer portion  228  provides transmission, distribution and shaping for an optical beam. Integrated circuit layer portion  230  provides control and configuration of optical layer portion  228 . Optical layer portion  228  includes an array aperture  232  and an optical feed  234 . Array aperture  232  provides steering for an optical beam. Optical feed  234  provides a conduit for an optical beam. 
     Array aperture  232  includes an array of crossed optical waveguides with a sampling noted as an optical waveguide  236 . An optical waveguide is a physical structure for guiding electromagnetic waves in the optical spectrum. The rows and columns associated with the array of crossed optical waveguides are spaced pseudo-randomly in order to minimize cross-coupling while providing adequate array element density and side-lobe control. Optical waveguides are fabricated in an electro-optic (EO) material. As a non-limiting example, the EO material may be polymethyl methacrylate. 
     Optical waveguides are controlled via a steering electrodes portion  237  with a sampling noted as a steering electrode  238 . 
     Steering electrodes control the phase of the light at the associated intersections and as a result perform optical beam steering. For an N×N array of optical waveguides, an associated 2N steering electrodes are provided. The steering electrodes are located on the back side of optical layer portion  228  enabling control by integrated circuit layer portion  230 . 
     Integrated circuit layer portion  230  receives and translates beam steering directions received from processor portion  208  into information for controlling the steering electrodes. As a non-limiting example, information may be conveyed from integrated circuit layer portion  230  to steering electrodes via a voltage. 
     A ground plane (not shown) is configured by placing of an L-shaped electrode on top of optical layer portion  228  and over the steering electrodes. A plurality of intersections is formed at the location where the optical waveguides cross with a sampling noted as an intersection  240 . 
     Optical feed  234  includes a cascade of multimode-interface (MMI) splitters providing distribution of an optical beam. Optical waveguides are fed along their lower edge by edge-coupled optical fibers traversing extendable mast  203  and terminating in enclosure  202 . Optical fibers carry optical power from transmitter portion  216  and to receiver portion  214 . 
     As a non-limiting example, polymethyl methacrylate yields an average waveguide period of 9 μm. Furthermore, as a non-limiting example, for N=1000, the 9 μm spacing yields a total array size of 9×9 mm. Furthermore, as a non-limiting example, the steering electrodes and MMI splitters occupy approximately 5 mm of length for optical layer portion  228  resulting in an area size for array aperture  232  of approximately 15×15 mm. 
     The extendibility of extendable mast  203  enables obstacle clearance and sufficient range to the optical horizon. 
     In operation, solar panel portion  218  receives light energy (e.g. Sun) and converts the light energy to electrical energy. The generated electrical energy is transferred to and stored by battery portion  206 . Battery portion  206  provides electrical power to electrical and electronic devices associated with node  102 . GPS receiver  212  receives and processes positioning and time information by way of GPS satellites, GPS antenna  222  and electrical cable portion  226 . 
     A laser portion  210  provides an optical light beam to optical phased array  220  via laser portion  210  and optical fiber portion  224 . Processor portion  208  determines and communicates beam steering information to optical phased array  220  via electrical cable portion  226 . Integrated circuit layer portion  230  receives and processes steering information and communicates configuration information to steering electrodes portion  237 . Steering electrodes configure beam shape for transmitted beam. 
     Transmitted beam traverses external to node  102 , impinges on external objects and is reflected back to node  102 . Reflected beam is received by optical phased array  220  and communicated to receiver portion  214  via optical fiber portion  224 . Receiver portion  214  communicates received information to processor portion  208 . Processor portion  208  receives and processes information for determining information associated with external objects. Processor portion  208  communicates processed information associated with external objects to external nodes via transmitter portion  216 , optical fiber portion  224  and optical phased array  220 . 
     External nodes receive and process information. External nodes communicate processed information to processor portion  208  by way of optical phased array  220 , optical fiber portion  224  and receiver portion  214 . Processor portion  208  receives and processes information from external nodes. 
       FIG. 3  is a more detailed block diagram for node  102  as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Integrated circuit layer portion  230  receives information from processor portion  208  via a communication channel  302 . Receiver portion  214  receives information from optical layer portion  228  via an optical communication channel  304 . Optical layer portion  228  receives information from transmitter portion  216  via an optical communication channel  306 . Battery portion  206  receives electrical power from solar panel portion  218  via a power conduit  308 . Optical phased array  220  receives electrical power from battery portion  206  via an electrical power conduit  310 . Processor portion  208  receives electrical power from battery portion  206  via an electrical power conduit  312 . GPS antenna  222  receives information from external entities via a communication channel  314 . GPS receiver  212  receives information from GPS antenna  222  via a communication channel  316 . Steering electrodes portion  237  receives information from integrated circuit layer portion  230  via a communication channel  318 . Optical layer portion  228  receives information from steering electrodes portion  237  via a communication channel  320 . Optical layer portion  228  communicates bi-directionally with external entities and performs detection, classification and tracking via an optical communication channel  324 . 
     Further, in some embodiments at least one of processor portion  208 , GPS receiver  212 , receiver portion  214 , transmitter portion  216 , optical phased array  220 , optical layer portion  228 , integrated circuit layer portion  230  and steering electrodes portion  237  may be implemented as a computer having stored therein tangible computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such tangible computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. Non-limiting examples of tangible computer-readable media include physical storage and/or memory media such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a tangible computer-readable medium. Combinations of the above should also be included within the scope of tangible computer-readable media. 
     In operation, solar panel portion  218  receives light energy (e.g. Sun) and converts the light energy to electrical energy. The generated electrical energy is transferred to and stored by battery portion  206  via electrical power conduit  308 . Battery portion  206  provides electrical power to electrical and electronic devices associated with node  102  including processor portion  208  via electrical power conduit  312  and optical phased array  220  via electrical power conduit  310 . 
     GPS receiver  212  receives and processes positioning and time information by way of GPS satellites (not shown), communication channel  316 , GPS antenna  222  and communication channel  314 . Transmitter portion  216  provides an optical light beam to optical layer portion  228  via optical communication channel  306 . Processor portion  208  determines and communicates beam steering information to integrated circuit layer portion  230  via communication channel  302 . Integrated circuit layer portion  230  receives and processes steering information and communicates configuration information to steering electrodes portion  237 . 
     Steering electrodes configure beam shape for transmitted beam. Transmitted beam traverses external to node  102  via optical communication channel  324 , impinges on external objects and is reflected back to node  102 . Reflected beam is received by optical layer portion  228  and is communicated to receiver portion  214  via optical communication channel  304 . Processor portion  208  receives reflected beam information via receiver portion  214 . Processor portion  208  processes received information for determining information associated with external objects. Processor portion  208  communicates processed information associated with external objects to external nodes via transmitter portion  216 , optical communication channel  306  and optical layer portion  228 . 
     External nodes receive and process information. External nodes communicate processed information to processor portion  208  by way of optical layer portion  228 , optical communication channel  304  and receiver portion  214 . Processor portion  208  receives and processes information from external nodes. 
       FIG. 4  is an example illustration for the operational modes  400  for intruder network system  100  as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Operational modes  400  include a search mode  402 , a classification mode  404 , a tracking mode  406 , a communication mode  408  and a third-party acquisition mode  410 . 
     Intruder network system  100  executes a plurality of modes for operation including searching, classifying, tracing, communicating and third-party acquiring. 
     For search mode  402 , a node (e.g. node  102 ,  104  and/or  106  as described with reference to  FIG. 1 ) transmits lidar beams and receives reflected lidar beams in order to detect the presence of a potential intruder. 
     In search mode  402 , lidar beams are swept through the monitoring area in a pseudorandom pattern. The lidar beams are configured in a pseudorandom pattern in order to aid in defeating potential countermeasures. The transmitted lidar beams are reflected by external elements and received by the node. As an example, the node compares previous received reflected lidar beams with recently received lidar beams in order to determine movement associated with an external element (e.g. person, intruder, vehicle, etc.). As a further example, a pattern of reflected lidar beams received similar to previous lidar beams would indicate the absence of a potential intruder and a pattern of reflected lidar beams received dissimilar to previous lidar beams may indicate the presence of a potential intruder. 
     For classification mode  404 , a node, following detection of a potential intruder, performs classification of the potential intruder. In the classification mode  404 , intruder network system  100  transmits lidar beams with a fine pattern in order to get a high resolution representation of an intruder. The signature of the received intruder is then compared to a database of stored signatures in order to find a match for the intruder. For example, the intruder may be classified as an animal, human or vehicle. 
     In classification mode  404 , the node compares the signature of the received reflected lidar beam with signatures of known intruder elements (e.g. person, truck, dog, cat, etc.) for determining a match. Node may use any known method for processing signatures for determining a match. Furthermore, the node may process the shape and/or size of the potential intruder to determine interest in further processing for the potential intruder. 
     For tracking mode  406 , a node, following classification of a potential intruder, tracks the movement of the potential intruder. Based upon previous movements of the potential intruder estimates are generated for future movements of the potential intruder and processed for accuracy following movement of the potential intruder. 
     In tracking mode  406 , the node estimates future movements of the potential intruder based upon previous movements of the potential intruder. Furthermore, actual movements are compared to actual movements for determining accuracy of estimates. Estimates of future movements are refined based upon comparisons of actual versus estimated movements. 
     For communication mode  408 , a node, following completion for estimating future movements of potential intruder, communicates information associated with the potential intruder to other nodes and the control station. 
     In communication mode  408 , non-limiting examples of information communicated to other nodes include velocity vector, acceleration, location, size, shape and estimated future velocity vector, acceleration and location. 
     For third-party acquisition mode  410 , a node, following receipt of information associated with a potential intruder, processes the received information in order to detect, classify and track the potential intruder. 
     In third-party acquisition mode  410 , a node receiving information from another node processes information to determine a configuration for detecting, classifying and tracking a potential intruder. Furthermore, node uses processed information for performing search mode  402 , classification mode  404 , tracking mode  406  and communication mode  408 . 
     A plurality of nodes aids in compensating for blockages associated with terrain or for mitigating potential countermeasures. As an example, a potential intruder may successfully blind a node, but other non-blinded nodes may track the potential intruder. 
     A node may transmit lidar beams and receive reflected lidar beams for detecting, classifying and tracking a potential intruder. The node may additionally transmit lidar beams and receive reflected lidar beams for communicating information associated with potential intruder to other nodes and to the control station with control station communication information associated with potential intruder to other nodes. Further, other nodes may transmit lidar beams and receive reflected beams for detecting, classifying and tracking a potential intruder. Still further, other nodes may transmit lidar beams and receive reflected lidar beams for communicating information associated with intruder to other nodes and to the control station. This will be described in greater detail with additional reference to  FIG. 5 . 
       FIG. 5  is an example illustration of a graph  500  for the operation of nodes as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Graph  500  includes a y-axis  501  with units of meters and an x-axis  502  with units of meters. 
     Node  104  (and node  106 ) transmits a plurality of lidar beams with a sampling noted as a lidar beam  503  and a lidar beam  504 . The beams may be transmitted in any predetermined pattern. In some examples, the lidar beams are transmitted in a pseudo-random pattern. The beam width of lidar beam  503  is noted as a beam width  506 . As a non-limiting example, beam width  506  is 0.01°. 
     Intruder  120  with a location noted as a geographic location  510  and with direction of movement noted as a velocity vector  512  is not detected at a location noted as geographic location  510 , as the distance between intruder  120  and node  104  is too large a distance for detection. 
     At a location for intruder  120  noted as a geographic location  514 , node  104  transmits a plurality of lidar beams with a sampling noted as a lidar beam  513 . Furthermore, transmitted lidar beams may be reflected by objects. Furthermore, a lidar beam  516  is reflected version of lidar beam  513  and noted as a reflected lidar beam  518 . As a non-limiting example, geographic location  514  for detecting intruder  120  may be realized nominally at 0.4 kilometers in an unobstructed view. 
     Node  104  receives reflected lidar beam  518  and other associated reflected lidar beams, processes reflected beams and detects movement associated with intruder  120 . 
     As a result of detecting intruder  120 , node  104  transmits a contiguous pattern of lidar beams in the direction of intruder  120 . Node  104  receives reflections from continuous pattern of lidar beams transmitted in direction of intruder  120  and performs a classification of intruder  120 . As a non-limiting example, node  104  may classify intruder  120  as human, dog, cat, horse and automobile. 
     At a location for intruder  120  noted as a geographic location  520 , node  104  tracks the location and movement of intruder  120  by estimating future information for intruder  120  followed by comparing estimated information with actually received information. 
     At a location for intruder  120  noted as a geographic location  522 , node  104  communicates to information associated with intruder  120  to control station  108  via a lidar beam  524 . Communication may be transmitted by node  104  and received by control station  108  during a periodic communication timeslot. Non-limiting examples of information communicated include node identification, node location, intruder coordinates and track state vector for correlation with the returns associated with other nodes. 
     At a location for intruder  120  noted as a geographic location  526 , control station  108  communicates information associated with intruder  120  to node  106  via a lidar beam  528 . 
     At a location for intruder  120  noted as a geographic location  530 , node  106  receives information associated with intruder  120  from node  104  via a lidar beam  532 . 
     Node  104  continues to periodically communicate updated information associated with intruder  120  to control station  108  and node  106 . Control station  108  continues to periodically communicate update information associated with intruder  120  to node  106 . 
     Node  106  monitors received information associated with intruder  120  and when intruder  120  is located at a geographic location  534  such that node  106  determines intruder  120  is within sufficient range for detection, node  106  transmits a lidar beam  536 . 
     Node  106  continues attempts track intruder  120  until node  106  successfully detects intruder  120  or until node  106  experiences a timeout condition and ceases detection efforts for intruder  120 . The timeout condition may be set at a predetermined time. As a non-limiting example, the timeout value for node  106  ceasing to attempt to detect intruder  120  is 10 minutes. 
     At a location for intruder  120  noted as a geographic location  538 , node  106  transmits a lidar beam  540  that is reflected by intruder  120  as noted by a reflected lidar beam  542 . Node  106  is able to detect, classify and track intruder  120  as a result of receiving reflected lidar beam  542  and successive reflected lidar beams. 
     At a location for intruder  120  noted as a geographic location  544 , node  106  communicates information associated with intruder  120  to control station  108  via a lidar beam  546  and to node  104  via a lidar beam  548 . 
     In an example embodiment a system in accordance with aspects of the present invention may perform intruder detection, classification and tracking during 0.9 of a second and perform communication activities during the remaining 0.1 of a second. The characteristics and design parameter values for such an example system will now be further described with reference to  FIG. 6 . 
       FIG. 6  is an example illustration of a table  600  for the characteristics and design parameter values for the system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Table  600  includes a characteristics table portion  602  and a design parameter table portion  604 . 
     Characteristics table portion  602  provides operational information associated with the system as described with reference to  FIG. 1 . Design parameter table portion  604  provides design parameter values associated with the design and fabrication of the system as described with respect to  FIG. 1 . 
     A row  606  notes a detection range of 400 meters with a 10% reflexivity for a human moving about the pace of a walk. A value for 10% reflexivity represents the target impinged by a lidar beam reflecting 10% of the received lidar beam. A row  608  notes a Free Space Optical (FSO) range of 1 kilometer. A value of 1 kilometer indicates the operational range of the system enclosed in a vacuum. A row  610  notes volume search coverage of 360 degrees with an azimuth of −0.1° to +0.4° in elevation. System may search in 360 degrees and with an azimuth of −0.1° to +0.4° in elevation. A row  612  notes volume search coverage period as less than 1 second for 2% of volume and fifty seconds for the plurality of beam positions. System may search 2% of the search volume in less than 1 second and may search in the aggregate of beam positions in 50 seconds or less. A row  614  notes a transition to track of less than five seconds. System is able to track a potential intruder in less than 5 seconds from first detection of potential intruder. A row  616  notes a track update rate of 1 Hz. System may update tracking information with other nodes and control system at a rate of 1 Hz. 
     A row  618  notes an energy per pulse of 1.6 micro Joule. The amount of energy transmitted in a pulse may be configured for 1.6 micro Joule. A row  620  notes a pulse width of four nanoseconds. The pulse width of a transmitted beam may be configured for four nanoseconds. A row  622  notes a pulse repetition interval of 25 microseconds. System may transmit pulses at a rate of once every 25 microseconds. A row  624  notes a pulse integration of 4 non-coherent pulses. A row  626  notes a target dwell time of 100 microseconds. A row  628  notes a range resolution of 0.6 meters. A row  630  notes a wavelength of 1550 nanometers. System may transmit and receive lidar beams with a wavelength of 1550 nanometers. A row  632  notes a F-number of 3. The F-number of for an optical lens represents the ratio of the focal length to the diameter of its clear aperture. A row  634  notes a beam width of 0.01°. System may transmit a beam with an angular width of 0.01°. A row  636  notes a pass band of elastic channel of 0.1 nanometer. A row  638  notes a quantum efficiency of 0.2. Quantum efficiency represents the percentage of photons received by a photo-reactive surface producing an electron-hole pair. A row  640  notes a receiver electronic bandwidth of twenty MHz. Electronics associated with system for transmitting/receiving an optical signal may have a bandwidth of twenty MHz. A row  642  notes a pre-amplifier current noise density of 2.12 e-12 (A/HZ) 1/2 . A row  644  notes an amplifier noise factor of 1. Amplifier noise factor represents the amount of excess noise added to a signal by an amplifier. A row  646  notes a non-multiplied dark current of 0.2 e nA. A row  648  notes a multiplied dark current of 0.2 e nA. A row  650  notes a detector noise factor of twenty. Detector noise factor represents the amount of excess noise added to a signal by a detector. A row  652  notes a detector current gain of 100. The ratio of the input signal to the output signal may be configured as 100. A row  654  notes a target area associated with a person as 11148 cm 2  (0.7×1.9 m). A row  656  notes a target reflectance of 0.1. Target reflectance indicates the amount of a beam is reflected and in this case indicates 10% of a beam received by a target is reflected. A row  658  notes an array loss of 6 dB. 
     At the powers and pulse widths as noted in design parameter table portion  604 , care needs to be taken in order to avoid damaging the optical components due to the small mode-field area (MFA) of the waveguides. The fibers connecting the lasers to the array faces have a MFA of about 80 μm 2  yielding a fluence of about 2 J/cm 2 . The array itself is a polymeric Electro-Optic (EO) material, with the input power divided equally among the plurality of the waveguides. Furthermore, the cascading splitter network that divides power is also polymeric. Coupling directly into a single polymer waveguide on each surface would result in a fluence of about 40 J/cm 2 , far in excess of the polymer&#39;s approximate 1-J/cm 2  damage threshold. To compensate for this issue, the optical layer is composed of multiple materials, with silica waveguides used for the first two stages of the cascading (Multi-Mode Interference) MMI splitter network (to go from 1 to 100 waveguides per side of the array) and polymer used for the last stage of the cascade (to go from 100 to 1000 waveguides) and the array itself. 
     The patterned silica waveguides are coupled directly to the polymer waveguides via lithography. Waveguides are fabricated of the same substrate material. 
     The communication mode for the system requires much less power than the lidar modes, therefore the lidar nodes dominate the power requirements for the system. Whether a solar array/battery configuration as described with reference to  FIG. 2  or a system supplied by grid electrical power depends upon the efficiency of the lidar transmitters selected. 
     Each array face has its own lidar transmitter and receiver, totaling four per node, so for lidar nodes each array operates in parallel and independently. Furthermore, a 250 mW fiber communications transmitter/receiver may be switched into the arrays, one at a time, according to the time window reserved for FSO communications. 
     Since lidar and communications are at 1550-nm wavelength, ranges may be affected by significant dust and fog. For example, at a fog visibility of 100-m visibility, the preceding node range would be reduced from nearly 400 m to 56 m at 1550-nm wavelength. In weather-based impairment is perceived by system, system may power down optical system and switch to operation using alternative methods. 
     Arrays are connected to independent laser sources and receivers and the four arrays may transmit and receive information in parallel. System seeks to search the volume and update tracking information every second. 
     For each array that scans 90° in azimuth and from −0.1° to +0.4° in elevation per second, 450,000 contiguous beams are transmitted. With 100 microseconds per beam dwell, it takes 45 seconds per volume scan for the various beam positions. In contrast, 10,000 dwells are achieved per second at 100 microseconds dwell intervals. To accomplish the volume update with few beams (10,000 versus 450,000), it is recognized that the cross-beam coverage at 500-m range is 8.7 cm. Therefore, for detection of objects of interest that are, for example, 0.5 m wide and 2 m tall, the system may be configured to transmit every fifth contiguous beam position in azimuth and every tenth beam position in elevation. In this manner, every transmitted azimuth beam position center is separated by approximately 44 cm, and each transmitted elevation beam position is separated by approximately 87 cm. Thus, a human, larger animal, or vehicle is covered by one of the distributed lidar beams. In order to further hedge against a potential intruder slipping through the volume of lidar beams, the system changes pulses every second, so that the plurality of beam position shave been covered in 45 seconds with 10,000 available beams. By using 2% of the 450,000 beam positions, 9000 per second are needed per array to adequately search the volume per second, with the plurality of the beam positions covered every 50 seconds. 
     For detection, a three-dimensional clutter map, storing information associated with a received echo or not received echo at each pulse resolution cell for each of the 450,000 beam positions (only partly updated per second, but fully updated every 50 seconds). A clutter map is used as opposed to Doppler detection in order to enable use of off-the-shelf, low-cost lidar systems. Even for expected detections of 400 m, detections may occur and for higher reflectivity objects out to 1 kilometer. Furthermore, 1500 range resolution cells result per beam position and 450,000 beam positions per array and with four arrays results in a clutter volume of 2.7 gigabytes. The memory of 2% of the memory cells is updated every second, with cells updated each 50 seconds. The detection algorithm determines physical motion by detecting changes in a number of contiguous cells over time. Once it is determined a grouping of cells of comparable range and angle have change, the node is directed to scan a 20×20 beam pattern for every other beam position over a 40×40 beam position area at that location as a priority interrupt from the search pattern. This would cover a 3.5×3.5-m cross-range at 500 m. If a significant portion of beam positions in this pattern receives echoes at about the same ranges, a detection is declared. During each successive second, a track-update beam is scheduled at the center of the detected beam pattern. Updates are entered into a track filter for each track. If a track update return is not received over several seconds, another 20×20 beam acquisition is attempted. Therefore, of the 9000 array dwells identified for each second, a multiple of 400 beams are interrupted for each transition to track. 
     When a detection has been determined and tracking initiate, the node transmits the track state data as well as the estimated cross-sectional area of the intruder to the nearby nodes and to the control system. At the control system, the cross-sectional area is an indication of intruder size and the tracking velocity indicates whether the intruder is potentially a vehicle traveling faster than a human. The information communicated by a node is used by other nodes to cue an acquisition of the intruding object. This further verifies the detection and maintains tracking by other nodes in case the intruder passes out-of-sight or behind obstacles with respect to the initial detection node. Due to Global Positioning System (GPS) uncertainty larger than the lidar beam and range accuracy, a receiving node may provide special monitoring of a beam patter covering the indicated location out to 5 to 10 meters on each side in azimuth depending upon ambiguity calculations for the target and lidar geometry. In this special region, the clutter map detector is set to high detection and corresponding false alarm probabilities in that area based on the acquisition message of a neighboring node. If the cued node makes a detection and transitions to a tracking process, it sends a message to neighboring nodes indicating a detection associated with the tracking state received by the cueing node that transmitted the tracking state. In this way, a basic swarming behavior is performed. 
     Since 10,000 dwells are available and 9,000 are used for detection, acquisition and tracking, 1000 dwells or 0.1 second per second is available for each array in order to communicate tracking and identification data via the FSO channel. Whereas four lidar sources and receivers, one for each array, one communication source for receipt is shared among the four arrays, with an array transmitting data in the direction of other nodes. At 100 Mbps, a total of 10 Mb may be transmitted and/or received at a time. Using a simple error detection and correction code of 12 bits per information bit, 0.8 Mb of data may be communicated per second per node. Using 32 bits per word, then 26,000 words per second may be sent or received from each node in the allocated 0.1-second window each second. 
     The system does not require mechanical gimbals since the optical phased arrays provide electronic beam pointing. At 1 kilometer of communication range between the neighboring nodes, it is sufficient that the transmitter aperture gain be used but significant receive aperture gain is not needed. Due to the short communication distances and low data rages, atmospheric turbulence compensation and advanced automatic gain control features are not needed. 
     A variety of network operational schemes may be devised for directive transmission and reception using combinations of time-division multiplexing (TDM) and wavelength-division multiplexing (WDM). As an example, for network initiation, each node is initially set for omni-directional reception in which the arrays are set to an approximate 0-dB gain (+1-3 dB). The control station transmits interrogation beams at low data rates, with an indication of GPS time, location and a node responsive time window. The control station beam sweeps in a 360° azimuth “interrogation” pattern. As individual nodes receive the interrogation, typically at different time frames, the nodes respond with high gain transmit beams pointing toward the control station within the indicated time window, during which time the monitor arrays are set to omni-directional gain. A number of potential interrogation response WDM channels are available from which each node is randomly assigned for transmission of a response. The control station can receive multiple responses at different WDM channels simultaneously for channel decoding during the response time windows. Alternatively, the nodes could use the same wavelength and, using GPS time synchronization, a TDM structure may be implemented in which each node takes turns communicating with the control station. FSO communications includes appropriate FSO error detection and correction coding and commercially available data encryption. The control station transmits interrogation beams followed by a listening time window for several cycles to ensure nodes have responded. The control station then communicates to each node a table of locations for the reporting nodes associated with the network. Following this, communications between nodes and control system are directional. 
     During each second using GPS time synchronization and position alignment, nodes perform surveillance, tracking, cued acquisition and intruder classification functions for the first 0.9 of a second and provide the remaining 0.1 second for transmission and reception of neighboring node acquisition cue tracking updates. During the 0.1-second window, nodes configure their arrays to receive from their nearest neighbors in anticipation of a potential acquisition cue message. Furthermore, nodes with tracking cue data transmit the associated information to their neighbors via their directive apertures. Furthermore, detections, tracking updates and identification images may be communicated to the control station during the 0.1-second window. The control station may also transmit commands to nodes during the 0.1-second window. 
     System may be applied to vehicle collision avoidance and control, short-range inter-vehicle communication and surveillance and communication inside of buildings. 
     In an example embodiment, successive sweeps of transmitted and reflected beams are used for determining the presence of a moving object. This will be further described with reference to  FIG. 7 . 
       FIG. 7  is an example illustration for a beam transmission chart  700  for the system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Beam transmission chart  700  includes a plurality of dotted first lidar beams with a sampling noted as a dotted first lidar beam  702  and a plurality of dashed second lidar beams with a sampling noted as a dashed second lidar beam  704 . 
     Dotted first lidar beam  702  indicates the transmission of a lidar beam and the reception of an associated echo if an echo occurs. The plurality of dotted first lidar beams represents a pattern of lidar beams transmitted in on second. The plurality of dashed second lidar beams represents a pattern of lidar beams transmitted in the second following the transmission of the dotted first lidar beams. For example, a dotted first lidar beam  706  follows the transmission of dotted first lidar beam  702 . Furthermore, a dotted first lidar beam  708  represents the last beam of the plurality of dotted first lidar beams transmitted. Furthermore, dashed second lidar beam  704  follows transmission of dotted first lidar beam  708 . 
     The distance between the dotted first lidar beams and the associated dashed second lidar beams is noted as a distance  710 . As a non-limiting example distance  710  may be configured for 15.2 cm. The distance between successive dotted first lidar beams is noted as a distance  712 . As a non-limiting example, distance  712  may be configured as 43.2 cm. The distance in height between one row of dotted first lidar beams and a following row of dotted first lidar beams is noted as a distance  714 . As a non-limiting example, distance  714  may be configured as 86.4 cm. The diameter of a dotted first lidar beam is noted as a diameter  716 . As a non-limiting example, diameter  716  may be configured as 7.9 cm. 
     The transmitted and reflected beams are used for detecting moving objects as noted by intruder  120  and a vehicle  718 . Comparisons between the sweeps of transmitted and reflected beams are performed for determining the movement of an object. For example, a plurality of beams reflected in one sweep of beams and a similar shaped reflection in a succession of following sweeps but in a different location may indicated the presence and movement of an object. 
     In an example embodiment a system in accordance with the present invention detects an intruder due to movement and change in distance between the intruder and node between sweeps of transmitted lidar beams. This will be further described with reference to  FIG. 8 . 
       FIG. 8  illustrates intruder detection for the example system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Four sweeps of lidar beam transmissions are presented with a first sweep of beam transmissions noted as a beam transmissions portion  802 , a second sweep of beam transmissions noted as a beam transmissions portion  804 , a third sweep of beam transmissions noted as a beam transmissions portion  806  and a beam transmissions noted as a beam transmission portion  808 . 
     Beam transmissions portion  802  is transmitted first, followed by beam transmissions portion  804 , followed by beam transmissions portion  806  and beam transmission portion  808 . 
     The distance between a rock  810  and node  104  is noted as a distance  812 . The location of rock  810  as observed by node  104  and the distance observed between rock  812  and node  104  does not change between sweeps of transmitted lidar beams. Therefore, node  104  does not detect rock  810  as an intruder. 
     The distance between a tree  814  and node  104  is noted as a distance  816 . The location of tree  814  may change between sweeps of transmitted lidar beams due to wind; however, the distance does not change between sweeps of transmitted lidar beams. Therefore, node  104  does not detect tree  814  as an intruder. 
     The location of intruder  120  is observed as changed by node  104  between sweeps of transmitted lidar beams. Furthermore, the distance between intruder  120  and node  104  as noted by a distance  818  is observed as different between the sweeps of transmitted lidar beams. For example, the location of intruder  120  as observed by beam transmissions portion  802  is observed as different from the location of intruder as observed by beam transmissions portion  804 . Furthermore, the distance between intruder  120  and node  104  is observed as being different between beam transmissions portion  802  and beam transmissions portion  804 . As a result of detecting a different location and movement in the direction of node  104 , intruder  120  is noted as an intruder. 
     Following detection as an intruder, node  104  performs classification and tracking for intruder  120 . Furthermore, node  104  communicates information associated with intruder  120  to other nodes and the control station. Furthermore, other nodes and control station may perform detection, classification, tracking and communication for intruder  120 . 
     In an example embodiment, a system in accordance with aspects of the present invention transmits lidar beams, lidar beams are reflected from external entities, reflected beams are detected and received to perform intruder detection, classification and tracking. Information associated with intruder detection, classification and tracking may be presented for viewing and communicated externally to other nodes and the control system. This will be further described with reference to  FIG. 9 . 
       FIG. 9  illustrates an example system as described with reference to  FIG. 1 , in accordance with an aspect of the present invention. 
     Intruder network system  100  includes processor portion  208 , an indicator portion  902 , an optical phased array portion  904  and a detector portion  906 . In this example, processor portion  208 , indicator portion  902 , optical phased array portion  904  and detector portion  906  are distinct elements. In some embodiments, at least two of processor portion  208 , indicator portion  902 , optical phased array portion  904  and detector portion  906  may be combined as a unitary device. 
     Further, in some embodiments at least one of processor portion  208 , indicator portion  902 , optical phased array portion  904  and detector portion  906  may be implemented as a computer having stored therein tangible computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. 
     Indicator portion  902  presents information associated with intruders. For example, indicator portion  902  may present location, size, movement and classification for an intruder. Optical phased array portion  904  performs beam shaping for a lidar beam. Detector portion  906  receives optical information transmitted by optical phased array portion  904  and reflected by external entities and receives optical information communicated from other nodes and the control station. Detector portion  906  converts optical communicated information to electrical communicated information. 
     Processor portion  208  includes receiver portion  214 , transmitter portion  216 , a detector portion  908 , a classifier portion  910 , a tracker portion  912  and a communication portion  914 . 
     Detector portion  908  performs detection of intruders. For example, detector portion  908  may detect the presence of an animal, human or a vehicle. Classifier portion  910  performs classification of intruders. For example, an intruder may be classified by classifier portion  910  as animal, human or vehicle. Tracker portion  912  tracks the location and movement of an intruder. For example, tracking portion may track that an intruder is 100 meters from a node and is traveling toward the node at 20 kilometers per hour. Communication portion  914  communicates information associated with detector portion  908 , classifier portion  910  and tracker portion  912  to external entities. 
     Detector portion  906  receives optical information via optical communication channel  324 . Receiver portion  214  receives information from detector portion  906  via a communication channel  918 . Detector portion  908  receives information from receiver portion  214  via a communication channel  920 . Classifier portion  910  receives information from receiver portion  214  via communication channel  920 . Tracker portion  912  receives information from receiver portion  214  via communication channel  920 . Indicator portion  902  receives information from detector portion  908  via a communication channel  922 . Indicator portion  902  receives information from classifier portion  910  via a communication channel  924 . 
     Indicator portion  902  receives information from tracker portion  912  via a communication channel  926 . Communication portion  914  receives information from detector portion  908  via communication channel  922 . Communication portion  914  receives information from classifier portion  910  via communication channel  924 . Communication portion  914  receives information from tracker portion  912  via communication channel  926 . Transmitter portion  216  receives information from communication portion  914  via a communication channel  928 . Optical phased array portion  904  receives information from transmitter portion  216  via a communication channel  930 . Optical phased array portion  904  transmits information via optical communication channel  324 . 
     In operation, processor portion  208  via way of transmitter portion  216  and optical phased array portion  904  transmit lidar beams via optical communication channel  324 . Transmitted beams are received by external entities and reflected back to detector portion  906  via optical communication channel  324 . Detector portion  906  converts received lidar beams to electrical information and communicates information to receiver portion  214 . 
     Receiver portion  214  provides received information to detector portion  908 , classifier portion  910  and tracker portion  912 . Detector portion  908  receives information from receiver portion  214  and performs detection of intruder or intruders. Classifier portion  910  receives information from receiver portion  214  and performs classification of an intruder or intruders. Tracker portion  912  receives information from receiver portion  214  and performs tracking of intruder or intruders. 
     Indicator portion  902  receives information from detector portion  908 , classifier portion  910  and tracker portion  912  and presents information based upon the results received from detector portion  908 , classifier portion  910  and tracker portion  912 . For example, if detector portion  908  indicates detection of an intruder, indicator portion  902  may indicated the presence of an intruder and if classifier portion  910  determines an intruder is a vehicle, then indicator portion  902  indicates the respective intruder as a vehicle, and if tracker portion  912  determines velocity of the intruder is 20 kilometers per hour, then indicator portion  902  indicates the velocity of the intruder is 20 kilometers per hour. 
     Communication portion  914  receives information from detector portion  908 , classifier portion  910  and tracker portion  912  and communicates information based upon the results received from detector portion  908 , classifier portion  910  and tracker portion  912 . Furthermore, communication portion  914  communicates information to external entities via transmitter portion  216 , optical phased array portion  904  and optical communication channel  324 . For example, if detector portion  908  indicates detection of an intruder, communication portion  914  may communicate the presence of an intruder and if classifier portion  910  determines an intruder is a vehicle, then communication portion  914  communicates the respective intruder as a vehicle, and if tracker portion  912  determines velocity of the intruder is 20 kilometers per hour, then communication portion  914  communicates the velocity of the intruder is 20 kilometers per hour. 
       FIG. 10  illustrates an example method  1000  for detecting, classifying, tracking and communicating information associated with an intruder, in accordance with an aspect of the present invention. 
     Method  1000  starts (S 1002 ) with a node (e.g. node  102 ) detecting geographic location via GPS (S 1004 ). For example, as described with reference to  FIG. 3 , processor portion  208  receives location information via communication channel  314 , GPS antenna  222  and GPS receiver  212 . As a non-limiting example, a node determines the time of day is 8:30 A.M. Eastern Standard Time (EST). 
     Returning to  FIG. 10 , the node then transmits lidar beams (S 1006 ). For example, as described with reference to  FIG. 3  and  FIG. 7 , processor portion  208  transmits sweeps of beams via transmitter portion  216 , optical layer portion  228  and optical communication channel  324 . As a non-limiting example, a node transmits a plurality of sweeps of lidar beams in 360° about the location of the node. 
     Returning to  FIG. 10 , the node then receives reflected lidar beams (S 1008 ). For example, as described with reference to  FIG. 5 , a reflected version of lidar beam  513  is reflected as reflected lidar beam  518 . As a non-limiting example, lidar beams are transmitted and reflected by an intruder moving towards the node. 
     Returning to  FIG. 10 , the node then processes reflected lidar beams (S 1010 ). For example, as described with reference to  FIG. 6 , the node creates and processes information associated with a three-dimensional clutter map. As a non-limiting example, a node transmits a first sweep of lidar beams, stores the reflected lidar beam information in first three-dimensional clutter map, transmits a second sweep of lidar beams, stores the reflected beam information in a second three-dimensional clutter map, then compares the two clutter maps to determine if an intruder has been detected. 
     Returning to  FIG. 10 , the node then detects intruder (S 1012 ). For example, after comparing the three-dimensional clutter maps, the node determines it has detected an intruder. As a non-limiting example, the reflected and processed lidar beams indicated an intruder has been detected. 
     Then the node classifies the detected intruder (S 1014 ). For example, the node compares signature information received for intruder and compares signature to know signatures for determining the class associated with the intruder. For example, the node may classify the intruder as an animal, human or vehicle. 
     Then the node tracks the intruder (S 1016 ). For example, the node processes received information for intruder to determine information associated with intruder. Non-limiting examples of information determined include velocity, location and size. As a non-limiting example, node determines intruder is a vehicle traveling at 20 kilometers per hours in the direction of the node. 
     Then the node communicates information associated with the intruder to other nodes and the control system (S 1018 ). For example, as described with reference to  FIG. 5 , the node initially detecting intruder communicates information associated with intruder to other nodes and to the control system. As a non-limiting example, node communicates the location of the intruder to the other nodes and the control system and communicates the intruder is a vehicle traveling toward the node at 20 kilometers per hour. 
     Returning to  FIG. 10 , then the other nodes and the control system detect, classify, track and communication information associated with intruder (S 1020 ). For example, as described with reference to  FIG. 5 , the other nodes and the control system perform processing associated with the intruder. As a non-limiting example, the control system detects, classifies and tracks intruder and communicates information associated with intruder to other nodes. 
     Returning to  FIG. 10 , execution of method  1000  terminates (S 1022 ). 
     An intruder network system has been presented for detecting, classifying and tracking an intruder via lidar. System includes a plurality of nodes transmitting lidar, receiving reflected lidar and processing reflected lidar. Furthermore, a node may communicate information associated with a potential intruder to other nodes via lidar. During the detection portion, lidar beams are transmitted in a sparse pattern enabling searching for an intruder over a particular volume of interest. During classifying and tracking portions, lidar beams are transmitted in a tight pattern over a small volume of interest where detection for an intruder was recognized. A node may communication information to other nodes via lidar by focusing and transmitting beams in the direction of other neighboring nodes. 
     The foregoing description of various exemplary embodiments of the invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above. The example embodiments, as described above, were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others of ordinary skill in the art to practice the invention in various embodiments and with various modifications as are suited to the particular use contemplated. The scope of the invention is defined by the following claims.