Defense mechanism against directed-energy systems based on laser induced atmospheric optical breakdown

Abstract

A laser defense system may be used to generate a plasma shield for protecting a structure against a directed-energy source. The laser defense system may include a short pulsed laser which generates plasma in a plasma shield region between the structure and the directed-energy source. Because plasma is opaque to electromagnetic radiation, the laser signal emitted by the directed-energy source is absorbed by the plasma shield rather than striking the structure.

What is claimed is: 
     
         1 . A defense system comprising:
 a pulsed laser source; and   an optical control system configured to direct laser signals emitted by the pulsed laser source to generate a plasma shield in a defined plasma shield region located between a target structure and a directed-energy source in order to protect the target structure from energy emitted by the directed-energy source.   
     
     
         2 . The defense system of  claim 1 , wherein the optical control system is configured to, during each pulse of the pulsed laser source, deflect a respective one of the laser signals to a defined sub-portion of the plasma shield region, wherein the plasma shield region is divided into a plurality of sub-portions. 
     
     
         3 . The defense system of  claim 2 , wherein the optical control system is configured to, using a plurality of pulses of the pulsed laser source, generate the plasma shield region by rastering the pulsed laser source in a predefined pattern through the plurality of sub-portions. 
     
     
         4 . The defense system of  claim 3 , wherein the optical control system further comprises a beam steering mechanism configured to deflect the laser signals to raster the pulsed laser source in the predefined pattern. 
     
     
         5 . The defense system of  claim 2 , wherein the optical control system is configured to generate the plasma in multiple sub-portions of the plurality of sub-portions simultaneously by splitting a laser signal emitted during a single pulse of the pulsed laser source into separate laser signals that each focus onto a respective one of the multiple sub-portions. 
     
     
         6 . The defense system of  claim 5 , wherein the optical control system comprises a lenslet configured to split the laser signal emitted during the single pulse into the separate laser signals. 
     
     
         7 . The defense system of  claim 1 , further comprising a lens to focus the laser signals to establish the plasma shield region at a predefined distance from the target structure. 
     
     
         8 . A laser defense system, comprising:
 at least one sensor configured to detect electromagnetic radiation emitted by a directed-energy source;   a laser source; and   an optical control system configured to, in response to detecting the electromagnetic radiation, direct a laser signal emitted by the laser source to generate a plasma in a defined plasma shield region.   
     
     
         9 . The laser defense system of  claim 8 , further comprising a plurality of sensors that includes the at least one sensor, wherein the plurality of sensors are disposed at different locations on a structure targeted by the directed-energy source. 
     
     
         10 . The laser defense system of  claim 8 , wherein the laser source does not emit the laser signal until the electromagnetic radiation is detected using the at least one sensor. 
     
     
         11 . The laser defense system of  claim 8 , wherein the laser source emits the laser signal before the electromagnetic radiation is detected using the at least one sensor. 
     
     
         12 . The laser defense system of  claim 8 , wherein the optical control system is configured to establish the plasma shield region based on a location of the directed-energy source such that the plasma shield region is between the directed-energy source and a structure targeted by the directed-energy source. 
     
     
         13 . The laser defense system of  claim 8 , wherein the laser source is a pulsed laser source and the plasma shield region is divided into a plurality of sub-portions, wherein the optical control system is configured to generate plasma in only one of the sub-portions during each pulse of the laser source. 
     
     
         14 . The laser defense system of  claim 8 , wherein the laser source is a pulsed laser source and the plasma shield region is divided into a plurality of sub-portions, wherein the optical control system is configured to generate plasma in multiple sub-portions of the plurality of sub-portions during each pulse of the laser source. 
     
     
         15 . A method, comprising:
 detecting electromagnetic radiation emitted by a directed-energy source that strikes a structure; and   generating, in response to detecting the electromagnetic radiation, plasma in a plasma shield region disposed between the directed-energy source and the structure.   
     
     
         16 . The method of  claim 15 , further comprising:
 identifying a location of the directed-energy source relative to the structure; and   determining a location of the plasma shield region based on the location of the directed-energy source so that the plasma shield region is disposed between the directed-energy source and the structure.   
     
     
         17 . The method of  claim 15 , wherein generating the plasma in the plasma shield region further comprises:
 rastering a laser source generating the plasma in a predefined pattern to generate the plasma shield region, wherein the predefined pattern divides the plasma shield region into a plurality of sub-portions.   
     
     
         18 . The method of  claim 17 , wherein generating the plasma in the plasma shield region further comprises:
 repeating the predefined pattern using a pulsed laser source before the plasma in any one of the sub-portions completely disappears.   
     
     
         19 . The method of  claim 15 , wherein generating the plasma in the plasma shield region further comprises:
 splitting a laser signal into a plurality of separate laser signals;   focusing each of the separate laser signals onto respective sub-portions of the plasma shield region, wherein the separate laser signals generate plasma in the sub-portions simultaneously.   
     
     
         20 . The method of  claim 19 , wherein splitting the laser signal is performed using a lenslet disposed between a laser source emitting the laser signal and the plasma shield region.