Pulsed terahertz frequency domain spectrometer with single mode-locked laser and dispersive phase modulator
First Claim
Patent Images
1. An apparatus for analyzing, identifying or imaging a target, comprising:
- a source of pulse signals in the range of frequencies from 100 GHz to over 2 THz including a first photoconductive switch activated by a pulsed optical beam from a laser resulting in a frequency spectrum f, 2f, 3f, . . . etc. where f is the order of 100 MHz;
a radiator for causing said signals to be substantially simultaneously focused on or through said target; and
a detector for acquiring spectral information reflected from said target and coupled to a second pulsed optical beam derived from said laser for generating an electrical signal representative of some characteristic of the target.
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Abstract
An apparatus for analyzing, identifying or imaging an target including a source of pulsed signals in the range of frequencies from 100 GHz to over 2 THz focused on or transmitted through the target; and a detector for acquiring spectral information from signals reflected from the target and using a multi-spectral heterodyning process to generate an electrical signal representative of some characteristics of the target. The source of pulse signals and the detector are photoconductive switches activated by a pulsed laser beam from a single mode-locked laser.
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Citations
28 Claims
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1. An apparatus for analyzing, identifying or imaging a target, comprising:
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a source of pulse signals in the range of frequencies from 100 GHz to over 2 THz including a first photoconductive switch activated by a pulsed optical beam from a laser resulting in a frequency spectrum f, 2f, 3f, . . . etc. where f is the order of 100 MHz; a radiator for causing said signals to be substantially simultaneously focused on or through said target; and a detector for acquiring spectral information reflected from said target and coupled to a second pulsed optical beam derived from said laser for generating an electrical signal representative of some characteristic of the target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 24)
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10. An apparatus for analyzing, identifying or imaging a target, comprising:
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a source of pulse signals in the range of frequencies of from 100 GHz to 3 THz; a radiator for causing said signals to be substantially simultaneously focused or through said target; a detector including a photoconductive switch activated by a pulsed laser beam with the frequency spectrum f+Δ
f, 2(f+Δ
f), 3(f+Δ
f), . . . etc. where f is the order of 100 MHz and Δ
f is of the order of 2.5 KHz, for acquiring spectral information reflected from or transmitted through said target for generating an electrical signal representative of some characteristics of the target; and
means coupled to said detector for processing said electrical signal. - View Dependent Claims (11, 12, 25)
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13. A portable apparatus for analyzing, identifying or imaging a target, comprising:
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a housing capable of being supported by a user; a source of pulse signals in said housing including a single mode-locked laser, said signals having simultaneous respective frequencies of f, 2f, 3f, . . . etc. where f is the order of 100 MHz and said signals being in the range of frequencies from 100 GHz to over 2 THz; a radiator coupled to said source of pulsed signals for causing said signals to be focused on said target; a detector in said housing for acquiring spectral information reflected from or transmitted through said target and generating an electrical signal representative of some characteristics of the target; and a processor in said housing coupled to said detector for processing said electrical signal. - View Dependent Claims (26)
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14. A transceiver comprising:
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a mode-locked laser for generating a pulsed laser beam; a beam splitter for splitting said beam into first and second optical beams; a photoconductive switch activated by said first optical beam resulting in a frequency spectrum f, 2f, 3f, . . . etc. where f is the order of 100 MHz; and a detector including a photoconductive switch activated by said second optical beam with the frequency spectrum f+Δ
f, 2(f+Δ
f), 3(f+Δ
f), . . . etc. where Δ
f is of the order of 2.5 KHz, for acquiring spectral information reflected from or transmitted through said target and coupled to source for generating an electrical signal representative of some characteristics of the target. - View Dependent Claims (27)
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15. A method of identifying or imaging a target comprising:
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providing a single mode-locked laser for generating a pulsed laser beam; simultaneously transmitting a predetermined spectral pattern of pulse signals derived from said pulsed laser beam to a target, said signals having respective frequencies of f, 2f, 3f, . . . etc. where f is the order of 100 MHz and said signals being in the range of frequencies from 100 GHz to over 2 THz; detecting the return signals in said frequency range after transmission through or reflection from said target by utilizing a detector tuned to said spectral pattern derived from said pulsed laser beam shifted by a sequence of non-identical small amounts from said spectral pattern; and analyzing said spectral information to identify said target or a compositional characteristic thereof. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 28)
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Specification