Terahertz frequency domain spectrometer with a single photoconductive element for terahertz signal generation and detection
First Claim
1. An apparatus for analyzing, identifying or imaging a target, the apparatus comprising:
- a laser system operable to generate first and second laser beams having respective different frequencies, and to combine the first and second laser beams in an optical path;
a photoconductive element provided in the optical path exposed to the combined first and second laser beams to emit electromagnetic radiation having a difference frequency dependent on a difference between said respective different frequencies of the first and second laser beams such that the electromagnetic radiation at the difference frequency is incident on the target which produces a return electromagnetic radiation that is co-incident on the photoconductive element with the combined first and second laser beams and detected by the photoconductive element to produce a detection signal such that a single photoconductive element produces (i) the difference frequency that is incident on the target as well as (ii) the detection signal responsive to the return electromagnetic radiation; and
a processor for processing the detection signal to identify at least one characteristic of the target.
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Accused Products
Abstract
There is described an apparatus for analyzing, identifying or imaging a target. The apparatus comprises a laser system which generates first and second laser beams having respective different frequencies, and directs the first and second laser beams along an optical path to a photoconductive material. An antenna structure is formed on the photoconductive material, the antenna structure comprises a first antenna for emitting electromagnetic radiation having a frequency dependent on the difference between said respective different frequencies of the first and second laser beams and a second antenna for generating a detection signal. A processor processes the detection signal to analyze, identify or image the target. The laser system is arranged such that the first and second laser beams overlap in a region of a surface of the photoconductive material having at least part of the first and second antennas formed thereon.
66 Citations
24 Claims
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1. An apparatus for analyzing, identifying or imaging a target, the apparatus comprising:
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a laser system operable to generate first and second laser beams having respective different frequencies, and to combine the first and second laser beams in an optical path; a photoconductive element provided in the optical path exposed to the combined first and second laser beams to emit electromagnetic radiation having a difference frequency dependent on a difference between said respective different frequencies of the first and second laser beams such that the electromagnetic radiation at the difference frequency is incident on the target which produces a return electromagnetic radiation that is co-incident on the photoconductive element with the combined first and second laser beams and detected by the photoconductive element to produce a detection signal such that a single photoconductive element produces (i) the difference frequency that is incident on the target as well as (ii) the detection signal responsive to the return electromagnetic radiation; and a processor for processing the detection signal to identify at least one characteristic of the target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for analyzing, identifying or imaging a target, the method comprising:
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generating first and second laser beams having respective different frequencies; combining the first and second laser beams in an optical path; directing the combined first and second laser beams along the optical path to a photoconductive element such that the photoconductive element emits electromagnetic radiation having a difference frequency corresponding to a difference between said respective different frequencies of the first and second laser beams, and the electromagnetic radiation at the difference frequency is incident on the target which produces a return electromagnetic radiation that is co-incident on the photoconductive element with the combined first and second laser beams and detected by the photoconductive element to produce a detection signal such that a single photoconductive element produces (i) the difference frequency that is incident on the target as well as (ii) the detection signal responsive to the return electromagnetic radiation; and processing the detection signal to identify at least one characteristic of the target. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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Specification