Patents by Inventor Xi-Cheng Zhang
Xi-Cheng Zhang has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7531802Abstract: A method of analyzing a remotely-located object includes the steps of inducing a volume of an ionized ambient gas to emit pulsed terahertz radiation directed toward a targeted object by focusing an optical pump beam in the volume and ionizing another volume of the ambient gas to produce a sensor plasma by focusing an optical probe beam in the other volume of ambient gas. The interaction, in the sensor plasma, of the focused optical probe beam and an incident terahertz wave, which is produced by the targeted object reflecting, scattering, or transmitting the pulsed terahertz radiation, produces a resultant radiation. Detecting an optical component of the resultant radiation emitted by the sensor plasma facilitates detection of a signature of the targeted object imposed onto the incident terahertz radiation.Type: GrantFiled: December 14, 2006Date of Patent: May 12, 2009Assignee: Rensselaer Polytechnic InstituteInventors: Xi-Cheng Zhang, Jianming Dai, Xu Xie
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Publication number: 20090066948Abstract: Compact terahertz spectrometer. The spectrometer includes an optical beam both for generating terahertz radiation for interaction with the sample and for use in a detector. A DC heterodyne detector uses a DC field-induced second harmonic wave at a sensor plasma to serve as a local oscillator. The spectrometer has a bandwidth orders of magnitude larger than conventional THz spectrometers.Type: ApplicationFiled: September 7, 2007Publication date: March 12, 2009Applicant: HYDROELECTRON VENTURES, INC.Inventors: Nicholas Karpowicz, Xi-Cheng Zhang, Keith H. Johnson, Matthew Price-Gallagher
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Publication number: 20080239317Abstract: Methods and apparatus for detecting variations in electromagnetic fields, in particular, terahertz (THz) electromagnetic fields, are provided. The methods and apparatus employ polarization detection devices and controllers to maintain or vary the polarization of modulated signals as desired. The methods and apparatus are provided to characterize electromagnetic fields by directing the electromagnetic field and a probe beam upon an electro-crystal and detecting the modulation of the resulting probe beam. Detection of the modulation of the probe beam is practiced by detecting and comparing the polarization components of the modulated probe beam. Aspects of the invention may be used to analyze or detect explosives, explosive related compounds, and pharmaceuticals, among other substances. A compact apparatus, modular optical devices for use with the apparatus, sample holders, and radiation source mounts are also disclosed.Type: ApplicationFiled: January 11, 2008Publication date: October 2, 2008Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: Brian SCHULKIN, Xi-Cheng ZHANG, Thomas TONGUE, Jingzhou XU, Jian CHEN
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Publication number: 20080203306Abstract: A method of analyzing a remotely-located object includes the step of illuminating at least a portion of a targeted object with electromagnetic radiation to induce a phase transformation in the targeted object, wherein the phase transformation produces an emitter plasma, which emits terahertz radiation. The method also includes the step of ionizing a volume of an ambient gas to produce a sensor plasma by focusing an optical probe beam in the volume and the step of detecting an optical component of resultant radiation produced from an interaction of the focused optical probe beam and the terahertz radiation in the sensor plasma. Detecting an optical component of the resultant radiation emitted by the sensor plasma facilitates detection of a characteristic fingerprint of the targeted object imposed onto the terahertz radiation produced as a result of the induced phase transformation.Type: ApplicationFiled: August 7, 2007Publication date: August 28, 2008Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: Xi-Cheng Zhang, Jianming Dai, Xu Xie
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Publication number: 20080179526Abstract: A method and system for imaging an object includes transmitting distinguishable electromagnetic waves from a plurality of radiators of an antenna array, wherein each of the distinguishable electromagnetic waves is distinguishable from others by a detector. Each of the radiators transmits radiation comprising a different distinguishable electromagnetic wave. The method also includes imaging at least a portion of the antenna array onto a targeted object, wherein each image area of a plurality of image areas on the targeted object corresponds to an image of a respective radiator of the antenna array, and detecting a plurality of resultant electromagnetic waves, wherein the resultant electromagnetic waves are transmitted, scattered, or reflected by respective image areas on the targeted object in response to each of the respective image areas being illuminated by the radiation transmitted by the respective radiator of the source array.Type: ApplicationFiled: April 10, 2007Publication date: July 31, 2008Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: Jingzhou XU, Xi-Cheng Zhang
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Patent number: 7368280Abstract: A method for detecting specific associations between a tethered molecule and an untethered target molecule. The method comprises (1) selecting a tethered molecule; (2) alternately impinging THz radiation onto the tethered molecule and onto a sample including the tethered and untethered target molecules; (3) detecting the radiation impinged on the tethered molecule to form a reference signal and the radiation impinged on the sample to form a sample signal; and (4) comparing the reference signal with the sample signal to generate a specimen signal indicative of an association between the selected tethered and target molecules. The method will detect whether a selected tethered molecule and the desired target exhibit any affinity or, in cases where the affinity is known, will detect the presence of the target molecule in a sample. Also provided is an apparatus for detecting specific associations between a tethered molecule and an untethered target molecule.Type: GrantFiled: May 22, 2003Date of Patent: May 6, 2008Assignee: Rensselaer Polytechnic InstituteInventors: Xi-Cheng Zhang, Samuel Peter Mickan, Abdellah Menikh
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Publication number: 20080048122Abstract: A method for generating amplified terahertz radiation includes inducing a first volume of a gas to produce a seed plasma and emit pulsed seed terahertz radiation by focusing an optical seed beam in the first volume. The seed terahertz radiation is then amplified by focusing an optical gain beam to produce a gain plasma in a second volume overlapping with the pulsed seed terahertz radiation remote from the seed plasma. The method may be implemented in a system for detecting and analyzing a remotely-located object such as an explosive material, a biological agent, and a chemical agent.Type: ApplicationFiled: May 31, 2007Publication date: February 28, 2008Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: Xi-Cheng ZHANG, Jianming DAI, Xu XIE
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Publication number: 20070263682Abstract: A method for generating terahertz radiation includes inducing a background plasma in a volume of a gas by focusing a first optical beam in the volume, and generating pulsed terahertz radiation with enhanced generation efficiency by focusing a second time-delayed optical beam in the background plasma. The method may be implemented in a system for detecting and analyzing a remotely-located object.Type: ApplicationFiled: May 31, 2007Publication date: November 15, 2007Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: Xi-Cheng ZHANG, Jianming DAI, Xu XIE
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Patent number: 7242010Abstract: A broad bandwidth detector to measure intensity information of terahertz (THz) frequency pulses. The detector includes: coupling optics coupled to a coherent optical source; a GaSe substrate aligned such that the probe beam path intersects a first surface at a phase-matching angle; a polarization detector aligned in the probe beam path; and calculation means coupled to the polarization detector. The coupling optics direct the probe optical beam along a beam path that is substantially collinear with the pulse beam path of the THz frequency pulses. The polarization of the probe optical beam is varied based on interactions between the probe optical beam and the THz frequency pulses within the GaSe substrate. The polarization detector detects the varied polarization of the probe optical beam. The calculation means determine the intensity information of the THz frequency pulses based on the detected probe polarization of the probe optical beam.Type: GrantFiled: March 22, 2005Date of Patent: July 10, 2007Assignee: Rensselaer Polytechnic InstituteInventors: Kai Liu, Xi-Cheng Zhang, Jingzhou Xu
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Patent number: 7239775Abstract: An optical delay line for use with an optical source including input/output optics optically coupled to the optical source and a curved mirror with a reflective surface that is centered about an evolute curve of the delay line to retro-reflect light traveling along a delay line beam path tangent to the edge of the evolute curve. The input/output optics direct light from the optical source along the delay line beam path and direct delayed light from the delay line beam path out of the optical delay line along an output beam path. The input/output optics and/or the curved mirror rotate about the evolute curve at a selected angular speed. The reflective surface has a curvature based on a parametric curve that is calculated from the evolute curve such that the delay of the delay line varies according to a predetermined function as the input/output optics and/or the curved mirror rotate.Type: GrantFiled: March 8, 2005Date of Patent: July 3, 2007Assignee: Rensselaer Polytechnic InstituteInventors: Jingzhou Xu, Xi-Cheng Zhang
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Publication number: 20070145276Abstract: A method of analyzing a remotely-located object includes the steps of inducing a volume of an ionized ambient gas to emit pulsed terahertz radiation directed toward a targeted object by focusing an optical pump beam in the volume and ionizing another volume of the ambient gas to produce a sensor plasma by focusing an optical probe beam in the other volume of ambient gas. The interaction, in the sensor plasma, of the focused optical probe beam and an incident terahertz wave, which is produced by the targeted object reflecting, scattering, or transmitting the pulsed terahertz radiation, produces a resultant radiation. Detecting an optical component of the resultant radiation emitted by the sensor plasma facilitates detection of a signature of the targeted object imposed onto the incident terahertz radiation.Type: ApplicationFiled: December 14, 2006Publication date: June 28, 2007Applicant: RENSSELAER POLYTECHNIC INSTITUTEInventors: XI-Cheng ZHANG, Jianming DAI, Xu XIE
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Patent number: 7230245Abstract: A device for use with a source of radiation to provide a THz emission image representing a sample. The device comprises a substrate, a metallic probe having a tip adjacent to the substrate surface and a source of AC bias coupled between the probe tip and substrate. Radiation generated by the source of radiation is incident on the substrate surface in the vicinity of the probe tip and generates THz emission based at least on the AC bias coupled between the probe tip and substrate. A method for providing a THz emission image representing a sample is also provided.Type: GrantFiled: May 4, 2005Date of Patent: June 12, 2007Assignee: Rensselaer Polytechnic InstituteInventors: Xi-Cheng Zhang, Tao Yuan, Jingzhou Xu, Haewook Han
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Publication number: 20070009207Abstract: An optical delay line for use with an optical source including input/output optics optically coupled to the optical source and a curved mirror with a reflective surface that is centered about an evolute curve of the delay line to retro-reflect light traveling along a delay line beam path tangent to the edge of the evolute curve. The input/output optics direct light from the optical source along the delay line beam path and direct delayed light from the delay line beam path out of the optical delay line along an output beam path. The input/output optics and/or the curved mirror rotate about the evolute curve at a selected angular speed. The reflective surface has a curvature based on a parametric curve that is calculated from the evolute curve such that the delay of the delay line varies according to a predetermined function as the input/output optics and/or the curved mirror rotate.Type: ApplicationFiled: March 8, 2005Publication date: January 11, 2007Inventors: Jingzhou Xu, Xi-Cheng Zhang
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Patent number: 7129491Abstract: A method of obtaining a series of images of a three-dimensional object. The method includes the steps of transmitting pulsed terahertz (THz) radiation through the entire object from a plurality of angles, optically detecting changes in the transmitted THz radiation using pulsed laser radiation, and constructing a plurality of imaged slices of the three-dimensional object using the detected changes in the transmitted THz radiation. The THz radiation is transmitted through the object as a two-dimensional array of parallel rays. The optical detection is an array of detectors such as a CCD sensor.Type: GrantFiled: May 12, 2004Date of Patent: October 31, 2006Assignee: Rensselaer Polytechnic InstituteInventors: Bradley Ferguson, Shaohong Wang, Xi-Cheng Zhang
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Patent number: 7119339Abstract: A method of obtaining a series of images of a three-dimensional object by transmitting pulsed terahertz (THz) radiation through the entire object from a plurality of angles, optically detecting changes in the transmitted THz radiation using pulsed laser radiation, and constructing a plurality of imaged slices of the three-dimensional object using the detected changes in the transmitted THz radiation. The THz radiation is transmitted through the object as a scanning spot. The object is placed within the Rayleigh range of the focused THz beam and a focusing system is used to transfer the imaging plane from adjacent the object to a desired distance away from the object. A related system is also disclosed.Type: GrantFiled: May 12, 2004Date of Patent: October 10, 2006Assignee: Rensselaer Polytechnic InstituteInventors: Bradley Stuart Ferguson, Shaohong Wang, Xi-Cheng Zhang
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Publication number: 20060214114Abstract: A broad bandwidth detector to measure intensity information of terahertz (THz) frequency pulses. The detector includes: coupling optics coupled to a coherent optical source; a GaSe substrate aligned such that the probe beam path intersects a first surface at a phase-matching angle; a polarization detector aligned in the probe beam path; and calculation means coupled to the polarization detector. The coupling optics direct the probe optical beam along a beam path that is substantially collinear with the pulse beam path of the THz frequency pulses. The polarization of the probe optical beam is varied based on interactions between the probe optical beam and the THz frequency pulses within the GaSe substrate. The polarization detector detects the varied polarization of the probe optical beam. The calculation means determine the intensity information of the THz frequency pulses based on the detected probe polarization of the probe optical beam.Type: ApplicationFiled: March 22, 2005Publication date: September 28, 2006Inventors: Kai Liu, Xi-Cheng Zhang, Jingzhou Xu
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Patent number: 7091506Abstract: An apparatus and a method for the generation of high-energy terahertz radiation. The apparatus and method function by impinging optical radiation on the surface of a semiconductor substrate, creating a photo-generated dipole emitting terahertz radiation. Because it is desirable to orient the dipole perpendicular to the radiation direction to maximize the power of the terahertz radiation, the surface of the semiconductor is modified to achieve this desirable result. More specifically, three embodiments of the surface modification are disclosed: (1) a grating is created in the top surface of a GaAs semiconductor substrate, (2) an InAs film is formed on a Teflon base to create a grating structure on the semiconductor substrate, and (3) a grating is disposed in the surface of the semiconductor substrate such that the optical radiation engages the substrate at Brewster's angle.Type: GrantFiled: April 21, 2004Date of Patent: August 15, 2006Inventors: Xi-Cheng Zhang, Jingzhou Xu, Kai Liu
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Patent number: 7087902Abstract: Systems and methods for reconstructing a plurality of images of an object. An exemplary system includes a radiation source adapted to emit radiation at a plurality of frequencies; a lens with frequency-dependent focal length, such as a Fresnel lens, adapted to receive radiation modified by the object and to project onto a fixed image plane a frequency-dependent image of a slice of the object perpendicular to the radiation path; a sensor for capturing the frequency-dependent image of the object; and apparatus for facilitating creation and capture of a plurality of frequency-dependent images of the object at the plurality of frequencies. A system for reconstructing a tomographic image of the object further includes apparatus for assembling the plurality of frequency-dependent images to reconstruct the tomographic image. Methods and systems are described for use in the visible, audible, and THz frequency ranges and with broadband or narrowband radiation sources.Type: GrantFiled: April 17, 2003Date of Patent: August 8, 2006Assignee: Rensselaer Polytechnic InstituteInventors: Shaohong Wang, Xi-Cheng Zhang
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Publication number: 20060045807Abstract: A method for detecting specific associations between a tethered molecule and an untethered target molecule. The method comprises (1) selecting a tethered molecule; (2) alternately impinging THz radiation onto the tethered molecule and onto a sample including the tethered and untethered target molecules; (3) detecting the radiation impinged on the tethered molecule to form a reference signal and the radiation impinged on the sample to form a sample signal; and (4) comparing the reference signal with the sample signal to generate a specimen signal indicative of an association between the selected tethered and target molecules. The method will detect whether a selected tethered molecule and the desired target exhibit any affinity or, in cases where the affinity is known, will detect the presence of the target molecule in a sample. Also provided is an apparatus for detecting specific associations between a tethered molecule and an untethered target molecule.Type: ApplicationFiled: May 22, 2003Publication date: March 2, 2006Inventors: Xi-Cheng Zhang, Samuel Mickan, Abdellah Menikh
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Publication number: 20060022141Abstract: A device for use with a source of radiation to provide a THz emission image representing a sample. The device comprises a substrate, a metallic probe having a tip adjacent to the substrate surface and a source of AC bias coupled between the probe tip and substrate. Radiation generated by the source of radiation is incident on the substrate surface in the vicinity of the probe tip and generates THz emission based at least on the AC bias coupled between the probe tip and substrate. A method for providing a THz emission image representing a sample is also provided.Type: ApplicationFiled: May 4, 2005Publication date: February 2, 2006Inventors: Xi-Cheng Zhang, Tao Yuan, Jingzhou Xu, Haewook Han