초록 ▼

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).

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.

대표청구항 ▼

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

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. 2. The system of claim 1 wherein the second pulse operably heterodynes an emission from the specimen, caused by the first pulse, to the detector. 3. The system of claim 1 wherein the pulse shaper employs spectral phase functions with translational symmetry of pseudorandom binary series. 4. The system of claim 1 further comprising a controller automatically identifying an unknown specimen receiving the pulses based on a database containing information used for discrimination. 5. The system of claim 4 wherein the controller follows a protocol of different pulse sequences and records the corresponding detected outcomes then computes the probability of having identified the specimen based on the database. 6. The system of claim 4 wherein the specimen includes a biological pathogen. 7. The system of claim 4 wherein the specimen includes a harmful chemical molecule in a complex chemical environment. 8. The system of claim 1 further comprising a remote aerospace craft, the laser and shaper being attached to the craft and the craft operably emitting the laser beam pulses, the shaper continuously correcting the dispersion acquired in the beam path by propagation of the pulse during use. 9. The system of claim 1 further comprising multiphoton intrapulse interference created by the shaper acting upon the first pulse. 10. The system of claim 1 further comprising a controller, the detector being connected to the controller, and the controller automatically varying a sampling rate of the detector depending upon its identification results. 11. The system of claim 1 wherein both of the pulses are in the near-infrared to infrared. 12. The system of claim 1 further comprising a beam splitter, mirrors and the telescope used to direct and focus at least one of the pulses. 13. The system of claim 1, wherein the laser includes an optical parametric amplifier to generate the laser beam which includes a broad bandwidth pulse. 14. The system of claim 1 wherein the laser is a Ytterbium fiber laser. 15. The system of claim 1 wherein the controller causes the system to automatically sample air at the specimen multiple times per second. 16. The system of claim 1 wherein the same telescope also collects the sensed Raman characteristic using a confocal arrangement. 17. The system of claim 1 further comprising a second telescope located in a detection path and the first telescope being in an excitation path. 18. The system of claim 1 further comprising a library of pulse shapes accessed by the controller for use by the pulse shaper, the library being field updatable. 19. The system of claim 1 wherein the specimen is an explosive located in a chemically complex background. 20. The system of claim 1 wherein the laser has a pulse intensity of at least 1 micro-Joule. 21. A system comprising: 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, anda 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; andfurther 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. 22. The system of claim 21 further comprising telescope optics mounted to the moveable remote location which is a flying aerospace craft, the laser and shaper being attached to the craft and the craft operably emitting the laser beam pulses, the shaper correcting phase distortions in the laser and the telescope optics and actively correcting group velocity dispersion introduced by the rapidly varying beam path. 23. The system of claim 21 further comprising a controller automatically identifying an unknown specimen receiving the pulses, the controller being located in the moveable remote location. 24. The system of claim 21 wherein the specimen is located in a complex chemical environment. 25. The system of claim 21 wherein at least one of the pulses is infrared. 26. The system of claim 21 wherein the detector is connected to the computer, the computer automatically varies a sampling rate of the detector depending upon its identification results, the detector samples and the computer identifies the results multiple times per second. 27. An environmental monitoring system comprising: 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; anda 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. 28. The system of claim 27 wherein the femtosecond laser operably creates a laser beam pulse of less than 21 femtosecond duration and at least 1 micro-Joule intensity. 29. The system of claim 27 wherein the laser is a fiber laser, and the computer automatically identifies the specimen in an outdoor environment by comparing the detected Raman characteristics against pre-stored data which can be updated in the field. 30. The system of claim 27 further comprising multiphoton intrapulse interference used by the shaper for at least one of pulse characterization and compensation. 31. The system of claim 27 wherein the computer automatically determines if a biological pathogen is present in the specimen. 32. The system of claim 27, wherein the laser includes an optical parametric amplifier to generate the laser beam which includes a broad bandwidth pulse. 33. The system of claim 27 wherein the laser is a Ytterbium fiber laser. 34. The system of claim 27 further comprising a library of pulse shapes accessed by the computer for use by the pulse shaper, the library being field updatable. 35. The system of claim 27 wherein the laser and detector are located in an aerospace craft. 36. The system of claim 27 wherein the computer causes the system to automatically sample air at the specimen at least once per minute. 37. The system of claim 27 wherein the computer causes the system to automatically sample air at the specimen multiple times per second. 38. The system of claim 27 wherein the same telescope also collects the sensed Raman characteristic using a confocal arrangement. 39. The system of claim 27, further comprising a second telescope located in a detection path and the first telescope located in an excitation path. 40. A method of monitoring an area, the method comprising: (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. 41. The method of claim 40, further comprising monitoring the area in repetitive intervals of about one minute or less for a nominal condition. 42. The method of claim 41 further comprising monitoring the area in repetitive intervals of at least 1000 times per minute if suspicious molecules are identified. 43. The method of claim 40 further comprising moving a laser relative to the specimen while the laser is emitting the pulses. 44. The method of claim 40 further comprising controlling nonlinear optical processes induced by the laser pulses in a calculated manner without inversion procedures, and the telescope focusing the shaped pulses at the specimen. 45. The method of claim 40 wherein the computer uses both of the coherent and spontaneous Raman emissions from the specimen to identify the specimen. 46. The method of claim 40 further comprising using the computer to determine if the specimen is an explosive in complex chemical environment. 47. The method of claim 40 further comprising obtaining a detection signal only within a confocal region near a focus of a laser. 48. The method of claim 40 further comprising using the multiphoton intrapulse interference to achieve selective excitation of at least one vibrational frequency of the specimen. 49. A system comprising: 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; ande) a spectrometer detecting both coherent and spontaneous Raman characteristics which are sent to the controller for identification using the library. 50. The system of claim 49 wherein the laser is a Ytterbium fiber laser. 51. The system of claim 49 wherein the laser, shaper, telescope and spectrometer are all remotely located away from and capable of moving relative to an explosive specimen during the laser pulse emissions and Raman detection. 52. The system of claim 49 wherein the detection and identification occurs in repetitive intervals of about one minute or less.