Ultra-fast laser system
First Claim
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1. A system comprising:
- (a) a laser operable to emit a first laser pulse having a duration equal to or less than 20 femtoseconds;
(b) a programmed controller;
(c) a pulse shaper controlled by the controller to correct phase distortions in a path of the pulse and optimized to cause selective stimulated Raman scattering at a specific molecular bond frequency and not at other undesired frequencies, the pulse shaper being operable to control a phase of the pulse;
(d) a second narrower-bandwidth pulse detuned from the first pulse carrying a probe photon, the second pulse being delayed from the first pulse by less than about 10 picoseconds;
(e) a telescope focusing at least one of the pulses at a specimen; and
(f) a detector operable to detect both coherent and spontaneous Raman characteristics of the specimen caused by at least one of the pulses striking the specimen, the laser and detector being remotely located at least 10 meters away from the specimen during the emission and detection.
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Abstract
A laser system is provided which selectively excites Raman active vibrations in molecules. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and remote sensing.
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Citations
52 Claims
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1. A system comprising:
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(a) a laser operable to emit a first laser pulse having a duration equal to or less than 20 femtoseconds; (b) a programmed controller; (c) a pulse shaper controlled by the controller to correct phase distortions in a path of the pulse and optimized to cause selective stimulated Raman scattering at a specific molecular bond frequency and not at other undesired frequencies, the pulse shaper being operable to control a phase of the pulse; (d) a second narrower-bandwidth pulse detuned from the first pulse carrying a probe photon, the second pulse being delayed from the first pulse by less than about 10 picoseconds; (e) a telescope focusing at least one of the pulses at a specimen; and (f) a detector operable to detect both coherent and spontaneous Raman characteristics of the specimen caused by at least one of the pulses striking the specimen, the laser and detector being remotely located at least 10 meters away from the specimen during the emission and detection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A system comprising:
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a first laser beam pulse equal to or less than 20 femtosecond duration and at least 1 micro-Joule intensity, including at least one of;
(i) a pump photon and (ii) a Stokes photon;a second laser beam pulse having a narrower bandwidth and different color than the first pulse, the first pulse carrying a spectral phase function optimized to selectively excite a molecular bond frequency of an explosive specimen, and the second pulse being delayed in emission from the first pulse and further being operable to heterodyne the emitted signal; a spectrometer detector; the second pulse operably carrying an emission from the explosive specimen, caused by the first pulse, to the detector; a pulse shaper operably varying a shape of at least one of the pulses in response to computer control of the shaper, and a moveable remote location spaced at least 0.5 meter from the explosive specimen, the laser beam pulses being emitted from the moveable remote location, and the spectrometer moving with the moveable remote location during its sensing of the emission; wherein the detector collects both coherent and spontaneous Raman emissions from the specimen; and further comprising a telescope through which at least one of the pulses is transmitted, the specimen being at least 10 meters away from the a laser, the telescope, the shaper and the telescope during pulse emission and spectrometer detection. - View Dependent Claims (22, 23, 24, 25, 26)
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27. An environmental monitoring system comprising:
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a femtosecond laser operable to emit a laser beam of less than about 51 femtosecond pulse duration upon a specimen; a pulse shaper operable to shape the laser beam pulse; a telescope operably focusing the shaped pulse at the specimen; a detector, remotely located at least 10 meters away from the specimen, operably sensing both coherent and spontaneous Ramon active characteristics of the specimen after activation by the laser beam; and a computer automatically varying pulse shaping performance of the pulse shaper for subsequent laser beam emissions, the computer operably identifying Raman active vibration characteristics of the specimen, the computer automatically identifying if the specimen is an explosive from an otherwise chemically complex background in a calculated manner with the assistance of the coherent and spontaneous Raman characteristics and free of inversion procedures. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method of monitoring an area, the method comprising:
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(a) emitting automatically varying shaped laser pulses through a telescope, at a specimen outside of a laboratory, at least one of the laser pulses having a duration equal to or less than 20 femtoseconds and an intensity of at least 0.7 mJ; (b) automatically comparing Raman active data detected at least in part by step (a) with Raman active data of acceptable background molecules; (c) automatically identifying harmful molecules based, at least in part, on the Raman active data comparisons; (d) controlling multiphoton intrapulse interference in the shaped pulses sent through the telescope; (e) automatically controlling and operating the emitting, analyzing, comparing and identifying steps by a computer at a remote location at least 10 meters away from the specimen within three shaped pulse emissions at the specimen, and (f) emitting the pulses and detecting the Raman active data at least 10 meters away from the specimen; and (g) detecting both coherent and spontaneous Raman emissions from the specimen. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48)
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49. A system comprising:
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a) a fiber laser emitting laser pulses each having a duration equal to or less than 20 femtoseconds, and an intensity of at least 1 micro-Joule, in an outside environment; b) a programmed controller, including a library of acceptable background data, unacceptable chemical data, and pulse shaping control data; c) a pulse shaper controlled by the controller to correct phase distortions and cause selective Raman activation, without inversion procedures; d) a telescope focusing the laser pulses on a remote location at least 0.5 meter away; and e) a spectrometer detecting both coherent and spontaneous Raman characteristics which are sent to the controller for identification using the library. - View Dependent Claims (50, 51, 52)
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Specification