Range-Enabled Three-Dimensional Imaging System and Associated Methods

Abstract

Systems and methods for three-dimensional (3-D) imaging enabled by natural range-dependent processes. Multiple lasers are configured to independently flash illuminate a target object to 3 - D image a resultant “scene” onto a focal plane array (FPA). The first laser produces a wavelength non-resonant with an atmospheric absorption line along the illumination path. The second laser produces a wavelength resonant with the atmospheric absorption line, and closely spaced with the non-resonant wavelength. A ratio of the respective intensities recorded at the FPA for the two wavelengths calculates a range to the target object.

1 - 20 . (canceled) 
     
     
         21 . A three-dimensional (3-D) imaging system for determining range to a target and comprising:
 a light source configured to illuminate a non-specular target with a wavelength A characterized by a reflectivity from the non-specular target;   a first active sensor adapted to receive a first backscatter signal associated with the wavelength A;   a second active sensor adapted to receive a second backscatter signal associated with the wavelength 1, the first active sensor adapted to measure a first intensity S1 i  of the first backscatter signal and the second active sensor adapted to measure a second intensity S2 i  of the second backscatter signal; and   a focal plane array adapted to determine a range to the target from a ratio of the first intensity S1 i  and the second intensity S2 i .   
     
     
         22 . The 3-D imaging system according to  claim 21 , where the light source comprises one of a laser and a solar illuminator. 
     
     
         23 . The 3-D imaging system according to  claim 21 , where the ratio of the first intensity S 1,i  and the second intensity S 2,i  is defined as
     S   1,i   /S 2 i = ƒ(R+o) /ƒ( R )= (R+o)     2     /R   2  
   where δ denotes a distance between the first active sensor and the second active sensor; and   where R denotes the range.   
     
     
         24 . The 3-D imaging system according to  claim 21 , where the first backscatter signal and the second backscatter signal are characterized by a change rate of f(R)=R −2 . 
     
     
         25 . A three-dimensional (3-D) imaging system for determining range to a target and comprising:
 a light source configured to illuminate a non-specular target with a wavelength A characterized by a reflectivity from the non-specular target;   a movable active sensor adapted to receive a backscatter signal associated with the wavelength A;   the first active sensor adapted to measure a first intensity S 1,i  of a first backscatter signal at a first position and to measure a second intensity S2 i  of a second backscatter signal at a second position; and   a focal plane array adapted to determine a range to the target from a ratio of the first intensity S1 i  and the second intensity S2 i .   
     
     
         26 . The 3-D imaging system according to  claim 25 , where the light source comprises one of a laser and a solar illuminator and the ratio of the first intensity S 1,i  and the second intensity S 2,i  is defined as
     S   1,i   /S   2,i = ƒ(R+o) /ƒ( R )= (R+o)     2     /R   2  
   where δ denotes a distance between the first active sensor and the second active sensor; and   where R denotes the range.   
     
     
         27 . The 3-D imaging system according to  claim 25 , where the first backscatter signal and the second backscatter signal are characterized by a change rate of ƒ(R)=R −2 . 
     
     
         28 . The 3-D imaging system according to  claim 25  adapted to measure a first intensity S a  associated with the first backscatter signal and measure a second intensity S b  associated with the second backscatter signal; and
 determine, independent of reflectivity, a range to the target from a ratio of the first intensity S a  and the second intensity S b , the ratio of the first intensity S a  and the second intensity S b  is defined as Sα/Sb=e −2R(α(λα)−α(λb)) ;
 where α denotes an atmospheric absorption and scattering attenuation factor for the absorption line; and 
 where R denotes the range; 
 where a respective reflectivity of the first wavelength λ a  and of the second wavelength λ b  are similar. 
 
 
     
     
         29 . The 3-D imaging system according to  claim 28 , where the first wavelength λ a  is in a relatively low atmospheric transmission band and the second wavelength λ b  is in a relatively high atmospheric transmission band, whereby the second wavelength transmission band is greater than the first wavelength transmission band. 
     
     
         30 . The 3-D imaging system according to  claim 28 , where the first wavelength λ a  is in a relatively high atmospheric transmission band and the second wavelength λ b  is in a relatively low atmospheric transmission band, whereby the first wavelength transmission band is greater than the second wavelength transmission band. 
     
     
         31 . The 3-D imaging system according to  claim 29 , where the first wavelength λ a  and the second wavelength λ b  differ by less than 0.015 micrometer (μm). 
     
     
         32 . The 3-D imaging system according to  claim 30 , where the first wavelength λ a  and the second wavelength λ b  differ by less than 0.015 micrometer (μm). 
     
     
         33 . The 3-D imaging system according to  claim 28 , where the first wavelength λ a  and the second wavelength λ b  have a pulse duration less than 10 ms. 
     
     
         34 . A three-dimensional (3-D) imaging system for determining range to a specular target and comprising:
 a light source configured to illuminate a specular target with a wavelength A characterized by a reflectivity from the specular target;   a first active sensor adapted to receive a first regular reflection associated with the wavelength A;   a second active sensor adapted to receive a second regular reflection associated with the wavelength 1, the first active sensor adapted to measure a first intensity S1 i  of the first regular reflection and the second active sensor adapted to measure a second intensity S2 i  of the second regular reflection; and   a focal plane array adapted to determine a range to the target from a ratio of the first intensity S1 i  and the second intensity S2 i .   
     
     
         35 . The 3-D imaging system according to  claim 34  where the ratio of the first intensity S 1,i  and the second intensity S 2,i  is defined as
     S   1,i   /S   2,i = ƒ(R+o) /ƒ( R )= (R+o)     2     /R   2  
 
 1 where δ denotes a distance between the first active sensor and the second active sensor; and 
 where R denotes the range. 
 
     
     
         36 . The 3-D imaging system according to  claim 35 , where the first regular reflection and the second regular reflection are characterized by a change rate of ƒ(R)=R −2 . 
     
     
         37 . The 3-D imaging system according to  claim 35  where the ratio of the first intensity S a  and the second intensity S b  is defined as 
       
         
           
             
               
                 
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         where α denotes an atmospheric absorption and scattering attenuation factor for the absorption line; and 
         where R denotes the range; 
         where a respective reflectivity of the first wavelength λ a  and of the second wavelength λ b  are similar. 
       
     
     
         38 . The 3-D imaging system according to  claim 37 , where the first wavelength λ a  and the second wavelength λ b  differ by less than 0.015 micrometer (μm). 
     
     
         39 . The 3-D imaging system according to  claim 38 , where the first wavelength λ a  and the second wavelength λ b  have a pulse duration less than 10 ms. 
     
     
         40 . The 3-D imaging system according to  claim 25 , where the first regular reflection and the second regular reflection are characterized by a change rate of ƒ(R)=R −2 .