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Browse by: INVENTOR PATENT HOLDER PATENT NUMBER DATE
 
 
Inventor:
Nelson; Keith A.
Address:
Newton, MA
No. of patents:
23
Patents:












Patent Number Title Of Patent Date Issued
7601977 Phase-matched terahertz emitter October 13, 2009
Methods and apparatus are disclosed for directing optical radiation to make multiple passes across an extended region of an electro-optic material, where during each pass the electro-optic material converts a portion of the optical radiation into terahertz radiation, and where the op
7495816 Diffraction-based pulse shaping with a 2D optical modulator February 24, 2009
Disclosed is a method including: (i) dispersing frequency components of an input EM waveform along a first direction with each frequency component spatially extended along a second direction different from the first direction; (ii) setting an amplitude for an output portion of each of th
7387027 Characterization of materials with optically shaped acoustic waveforms June 17, 2008
A method for characterizing one or more properties of a sample using acoustic waveforms is disclosed, and comprises directing a sequence of at least three optical pulses to the sample to generate an acoustic response in the sample at a frequency corresponding to the pulse sequence, varyi
7348569 Acceleration of charged particles using spatially and temporally shaped electromagnetic radiatio March 25, 2008
A method and apparatus for accelerating charged particles are disclosed, wherein the method comprises using at least a transverse component of a temporally and spatially shaped electromagnetic field to accelerate one or more charged particles.
6795198 Method and device for measuring thin films and semiconductor substrates using reflection mode ge September 21, 2004
The invention provides both a method and apparatus that measures a property of a structure that includes at least one layer. The apparatus features a laser (e.g., a microchip laser, described below) that generates an optical pulse, and a diffractive mask that receives the optical pulse a
6717717 Dynamic wavelength shifting method April 6, 2004
Methods and systems are disclosed that dynamically shift the wavelength of an electromagnetic (EM) beam by interacting the beam with a polariton wave having a selected polariton wave frequency.
6479822 System and Method for terahertz frequency measurements November 12, 2002
A spectroscopic method for characterizing a sample including: positioning the sample adjacent to a non-centrosymmetric material; directing at least one temporal pulse of coherent EM radiation into the non-centrosymmetric material to generate a polariton therein and cause EM radiation fro
6356349 Polariton wave imaging March 12, 2002
A method for characterizing a polariton wave within a material includes: generating the polariton wave; and imaging the polariton wave with optical radiation to produce a spatially-resolved image of portions of the optical radiation affected by the polariton wave. The method can be used
6349128 Method and device using x-rays to measure thickness and composition of thin films February 19, 2002
A method and apparatus for measuring a property (e.g., thickness or composition) of at least one film in a sample (e.g., a multilayer film stack contained in a microelectronic device) is disclosed. The method features the steps of generating a coherent x-ray pulse, delivering the coh
6348967 Method and device for measuring the thickness of opaque and transparent films February 19, 2002
A method for determining the thickness of a thin sample is described. The method includes the step of exciting time-dependent acoustic waveguide modes in the sample with an excitation radiation field. The acoustic waveguide modes are detected by diffracting probe radiation off a ripple
6204926 Methods and system for optically correlating ultrashort optical waveforms March 20, 2001
The invention features methods and systems for optical correlation of ultrashort optical waveforms, e.g., pulses. The optical waveform passes through a diffractive optic, e.g., a mask or grating, to generate multiple sub-beams corresponding to different diffractive orders. At least two o
6081330 Method and device for measuring the thickness of opaque and transparent films June 27, 2000
A method for determining the thickness of a thin sample is described. The method includes the step of exciting time-dependent acoustic waveguide modes in the sample with an excitation radiation field. The acoustic waveguide modes are detected by diffracting probe radiation off a ripple
6075640 Signal processing by optically manipulating polaritons June 13, 2000
The invention features methods and systems for processing signals by optically manipulating polaritons. In one embodiment, the signal processing method includes: converting a plurality of spatially separated input signals into polaritons that propagate in a signal processing material
6069703 Method and device for simultaneously measuring the thickness of multiple thin metal films in a m May 30, 2000
An apparatus for measuring a property of a structure comprising at least one layer, the appratus including a light source that produces an optical pulse having a duration of less than 10 ps; a diffractive element that receives the optical pulse and diffracts it to generate at least two
5999308 Methods and systems for introducing electromagnetic radiation into photonic crystals December 7, 1999
A method for introducing desired electromagnetic radiation into a photonic crystal having a photonic bandgap and at least one defect, wherein the desired electromagnetic radiation has a frequency within the photonic bandgap. The method includes the steps of: delivering source electro
5982482 Determining the presence of defects in thin film structures November 9, 1999
The invention features a method for detecting a subsurface defect in a thin film structure. The method includes: optically generating an acoustic wave in a first spatial region of the film; optically measuring a time-dependent reflection of the acoustic wave from subsurface features in
5812261 Method and device for measuring the thickness of opaque and transparent films September 22, 1998
A method for determining the thickness of a thin sample is described. The method includes the step of exciting time-dependent acoustic waveguide modes in the sample with an excitation radiation field. The acoustic waveguide modes are detected by diffracting probe radiation off a ripple
5734470 Device and method for time-resolved optical measurements March 31, 1998
An optical modulating system which allows modulation of a single light beam with a spatially filtering mask to form a spatially periodic, time-dependent excitation field. Once generated, the field can be used to induce a transient grating in a sample. The optical modulating system is
5719650 High-fidelity spatial light modulator February 17, 1998
A light modulator is described which generates an output optical field from an input optical field. The light modulator features first and second polarization-rotating elements which are directly attached to one another. Each element contains an array of pixels including liquid crystals
5682262 Method and device for generating spatially and temporally shaped optical waveforms October 28, 1997
A method and device for shaping both the temporal and spatial profiles of an input optical pulse to generate an output optical waveform are described. The method includes the step of dispersing the spectral frequencies of the input pulse. These frequencies are then focused with a cyl
5672830 Measuring anisotropic mechanical properties of thin films September 30, 1997
Anisotropic mechanical properties of thin films are measured by exciting time-dependent waveguide acoustic modes in the thin film sample with a pair of excitation pulses from an excitation laser. The waveguide acoustic modes are then optically detected by diffracting a probe laser beam o
5633711 Measurement of material properties with optically induced phonons May 27, 1997
Samples such as thin polymeric films are analyzed using optically induced phonons by excitation of the sample using radiation preferably absorbed by the sample and probe radiation, preferably not absorbed by the sample, that is diffracted from the surface of the sample. The pulse width o
5546811 Optical measurements of stress in thin film materials August 20, 1996
A method for determining the residual stress in an unsupported region of a thin film. The method includes the steps of (a) optically exciting the film with a spatially and temporally varying optical excitation field to launch counter-propagating acoustic modes along at least one wavevect










 
 
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