Method and apparatus for analyzing, identifying or imaging a target
First Claim
1. A method for analyzing, identifying, or imaging a target, said method comprising:
- providing first and second lasers, said first laser having a tunable frequency and configured to produce a first output beam and said second laser having a tunable frequency and configured to produce a second output beam, said first output beam and said second output beam having different frequencies, wherein the frequency of the first output beam is coarsely adjustable by temperature adjustment of the first laser and the frequency of the second output beam is coarsely adjustable by temperature adjustment of the second laser;
producing a first composite output beam from a first portion of said first output beam and a first portion of said second output beam;
producing a second composite output beam from a second portion of said first output beam and a second portion of said second output beam, wherein the second portion of the first output beam is coupled to a frequency control element for controllably finely adjusting the frequency of the second portion of the first output beam to finely adjust a frequency difference between the first composite output beam and the second composite output beam;
generating CW signals in the range of frequencies from 100 GHz to over 2 THz using said second composite output beam;
causing said CW signals to be substantially simultaneously focused on or through said target;
acquiring a spectral information signal from said target; and
generating an electrical signal representative of a characteristic of said target based on said spectral information signal and said first composite output beam.
1 Assignment
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Accused Products
Abstract
An apparatus for analyzing, identifying or imaging an target including first and second laser beams coupled to a pair of photoconductive switches to produce CW signals in one or more bands in a range of frequencies greater than 100 GHz focused on and transmitted through or reflected from the target; and a detector for acquiring spectral information from signals received from the target and using a multi-spectral heterodyne process to generate an electrical signal representative of some characteristics of the target. The lasers are tuned to different frequencies and a frequency shifter in the path of one laser beam allows the terahertz beam to be finely adjusted in one or more selected frequency bands.
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Citations
23 Claims
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1. A method for analyzing, identifying, or imaging a target, said method comprising:
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providing first and second lasers, said first laser having a tunable frequency and configured to produce a first output beam and said second laser having a tunable frequency and configured to produce a second output beam, said first output beam and said second output beam having different frequencies, wherein the frequency of the first output beam is coarsely adjustable by temperature adjustment of the first laser and the frequency of the second output beam is coarsely adjustable by temperature adjustment of the second laser; producing a first composite output beam from a first portion of said first output beam and a first portion of said second output beam; producing a second composite output beam from a second portion of said first output beam and a second portion of said second output beam, wherein the second portion of the first output beam is coupled to a frequency control element for controllably finely adjusting the frequency of the second portion of the first output beam to finely adjust a frequency difference between the first composite output beam and the second composite output beam; generating CW signals in the range of frequencies from 100 GHz to over 2 THz using said second composite output beam; causing said CW signals to be substantially simultaneously focused on or through said target; acquiring a spectral information signal from said target; and generating an electrical signal representative of a characteristic of said target based on said spectral information signal and said first composite output beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for analyzing, identifying, or imaging a target, said apparatus comprising:
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first and second lasers, said first laser having a tunable frequency and configured to produce a first output beam and said second laser having a tunable frequency and configured to produce a second output beam, said first output beam and said second output beam having different frequencies, wherein a first portion of said first output beam and a first portion of said second output beam produce a first composite output beam configured to be swept over a frequency band as the frequency of at least one of the first and second lasers is swept; a frequency shifting element coupled to a reference oscillator and positioned to receive a second portion of said first output beam to controllably shift the frequency of said second portion of said first output beam; a beam combiner coupled to an output the frequency shifting element and to a second portion of the second output beam to produce a second composite beam, wherein the frequency shifting element is configured to controllably finely adjust the frequency of the second portion of the first output beam to finely adjust a frequency difference between the first composite output beam and the second composite output beam; a first photoconductive switch activated by said second composite output beam to produce CW signals in the range of frequencies from 100 GHz to over 2 THz; a radiative element for causing said CW signals to be substantially simultaneously focused on or through said target; and a second photoconductive switch activated by said first composite output beam and positioned with respect to the target so as to acquire a spectral information signal from the target, and to generate, based on said spectral information and said first composite output beam and heterodyne down conversion, an electrical signal representative of a characteristic of said target. - View Dependent Claims (20, 21, 22, 23)
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Specification