Patents – Steven Chu

Chu Page · Resources with Additional Information · Interviews, Speeches, and Presentations


US 4,742,224 CHARGED PARTICLE ENERGY FILTER – Chu, Steven; et. al.; May 3, 1988
An ion energy filter of the type useful in connection with secondary ion mass spectrometry is disclosed. The filter is composed of a stack of 20 thin metal plates, each plate being insulated from the others and having a centrally located hole with a unique radius. A metallic hemisphere is mounted on a base plate, and the 20 thin metal plates are attached to the base plate such that the plate with the smallest central hole is adjacent to the base plate and the radii of the holes in subsequent plates increase with increasing distance from the base plate. The relative potential of each plate is determined by a series string of 20 resistors with each plate being connected to a different junction in the series string. The radii of the centrally located holes are selected such that the voltage on each plate is inversely proportional to the radius of its centrally located hole.

US 5,079,169 METHOD FOR OPTICALLY MANIPULATING POLYMER FILAMENTS – Chu, Steven; Kron, Stephen J.; January 7, 1992
Method and apparatus for manipulating a microscopic particle by single-beam gradient optical trapping, using an optical beam whose trapping force is substantially independent of position within a view field. The apparatus may be used to extend a polymer filament, and to fix the extended filament at a selected stretching force. When applied to nucleic acid filament, the method may be employed for genomic DNA mapping of filaments up to several megabasepairs in size. The method may also be used for studying the interaction of enzymes or ribosomes with extended DNA in real time.

US 5,274,231 METHOD AND APPARATUS FOR MANIPULATING ATOMS, IONS OR MOLECULES AND FOR MEASURING PHYSICAL QUANTITIES USING STIMULATED RAMAN TRANSITIONS – Chu, Steven; Kasevich, Mark A.; December 28, 1993
Quantum objects, such as atoms, ions, and molecules, are controllably moved by stimulating selected non-radiative energy levels within a quantum structure in accordance with the principles of stimulated Raman transitions. The movement is effected by timed excitation of individual quantum objects with preselected quantities ("pulses") of electromagnetic energy of at least two different frequencies which together are in resonance with a natural resonance (i.e., a stimulated Raman transition) of preferably metastable energy levels within the quantum object to cause a controlled change in momentum of the quantum object. Specific embodiments employ amplitude modulated collinear beams or multiple beams along different beam paths or collinear beams which are phase coherent but from independent laser sources. In alternative embodiments, single-pulse excitation or multiple-pulse sequence excitation with stimulated Raman transitions produce a controlled change in momentum of individual quantum objects according to the invention. A controlled distribution of velocities of an ensemble of quantum objects may be effected in accordance with the invention. The velocities of the quantum objects are changed and selected using the Doppler effect in both excitation and measurement.

US 5,274,232 METHOD AND APPARATUS FOR MANIPULATING ATOMS, IONS OR MOLECULES AND FOR MEASURING PHYSICAL QUANTITIES USING STIMULATED RAMAN TRANSITIONS – Chu, Steven; Kasevich, Mark A.; December 28, 1993
According to the invention, quantum objects, such as atoms, ions, and molecules, are controllably moved by stimulating selected non-radiative energy levels within a quantum structure in accordance with the principles of stimulated Raman transitions. The movement is effected by timed excitation of individual quantum objects with preselected quantities ("pulses") of electromagnetic energy of at least two different frequencies which together are in resonance with a natural resonance (i.e., a stimulated Raman transition) of preferably metastable energy levels within the quantum object to cause a controlled change in momentum of the quantum object. In alternative embodiments, single-pulse excitation or multiple-pulse sequence excitation with stimulated Raman transitions produce a controlled change in momentum of individual quantum objects according to the invention. A controlled distribution of velocities of an ensemble of quantum objects may be effected in accordance with the invention. The velocities of the quantum objects are changed and selected using the Doppler effect in both excitation and measurement. The invention may be used to measure forces such as gravity.

US 5,338,930 FREQUENCY STANDARD USING AN ATOMIC FOUNTAIN OF OPTICALLY TRAPPED ATOMS – Chu, Steven; et.al.; August 16, 1994
Beams of laser light trap and cool cesium atoms in a small vapor cell and put the atoms in a particular quantum mechanical state. The lasers are then configured so as to launch the atoms upward by shifting the frequencies of the vertically propagating lasers. The atoms pass through a microwave waveguide during both their ascent and descent. The microwave field is applied briefly each time the atoms are in the center of the waveguide so that the microwaves excite the cesium "clock" transition. Once the atoms have fallen back to where they started, the laser fields are turned on in a particular sequence. The fraction of the atoms that make a quantum mechanical transition is measured by observing the laser light scattered by the atoms. That signal indicates how close the microwave frequency is to the atomic transition. The laser cooling reduces the relative motion of the atoms so that the atoms can be observed longer. The resulting atomic resonance measured is much narrower.

US 5,512,745 OPTICAL TRAP SYSTEM AND METHOD – Chu, Steven; et.al.; April 30, 1996
By providing a focal region of light onto a particle, a laser-based light source can provide enough radiation pressure to position the particle at any desired location in space. In one application, the particle can be a micrometer-sized bead, called a handle, attached to a sample. When the sample under examination, such as an actin filament, interacts with other molecules, such as myosin, the forces generated may displace the sample, and thus the handle, out of its original position. To correct for the off-target position (or in other words, to increase the stiffness of the handle), a feedback loop that utilizes a quadrant photodiode detector and a focal region location means such as an acousto-optic modulator or galvanometer mirror is incorporated in the optical trap system. Use of two other light sources for brightfield illumination and epifluorescence allows the simultaneous viewing of the sample in real time. In other embodiments, the optical trap system can trap and manipulate particles.

US 5,528,028 FREQUENCY STANDARD USING AN ATOMIC STREAM OF OPTICALLY COOLED ATOMS – Chu, Steven; et. al.; June 18, 1996
Beams of laser light trap and cool cesium atoms in a small vapor cell and put the atoms in a particular quantum mechanical state. The lasers are then configured so as to launch the atoms upward by shifting the frequencies of the vertically propagating lasers. The atoms pass through a microwave waveguide during both their ascent and descent. The microwave field is applied briefly each time the atoms are in the center of the waveguide so that the microwaves excite the cesium "clock" transition. Once the atoms have fallen back to where they started, the laser fields are turned on in a particular sequence. The fraction of the atoms that make a quantum mechanical transition is measured by observing the laser light scattered by the atoms. That signal indicates how close the microwave frequency is to the atomic transition. The laser cooling reduces the relative motion of the atoms so that the atoms can be observed longer. The resulting atomic resonance measured is much narrower.

US 6,684,645 COOLING BY RESONATOR-INDUCED COHERENT SCATTERING OF RADIATION – Chu, Steven; Vuletic, Vladan; February 3. 2004
The invention relates to a method and apparatus for cooling multilevel entities such as atoms, ions or molecules as well as entities with no apparent internal structure. Cooling is achieved by coherent scattering, where the frequency of the emitted radiation exceeds the frequency of the illumination radiation. Such coherent scattering is achieved by placing the entities in a resonator containing in which the cavity length and mirror coating are selected to support a resonant radiation. The entities are illuminated with an illumination radiation whose energy is lower than that of the resonant radiation supported by the resonator by a certain detuning energy selected such that coherent scattering of resonant radiation from the entities at a higher frequency than that of the illumination radiation is promoted by the resonator. As a result of the coherent scattering energy is carried away from the entities and they are cooled.

US 7,013,739 SYSTEM AND METHOD FOR CONFINING AN OBJECT TO A REGION OF FLUID FLOW HAVING A STAGNATION POINT – Chu, Steven; et.al.; March 21, 2006
A device for confining an object to a region proximate to a fluid flow stagnation point includes one or more inlets for carrying the fluid into the region, one or more outlets for carrying the fluid out of the region, and a controller, in fluidic communication with the inlets and outlets, for adjusting the motion of the fluid to produce a stagnation point in the region, thereby confining the object to the region. Applications include, for example, prolonged observation of the object, manipulation of the object, etc. The device optionally may employ a feedback control mechanism, a sensing apparatus (e.g., for imaging), and a storage medium for storing, and a computer for analyzing and manipulating, data acquired from observing the object. The invention further provides methods of using such a device and system in a number of fields, including biology, chemistry, physics, material science, and medical science.

US 8,123,898 METHODS OF BONDING OPTICAL STRUCTURES, BONDING AND SILYLATION OF OPTICAL STRUCTURES, BONDED OPTICAL STRUCTURES, AND SILYLATED BONDED OPTICAL STRUCTURES – Chu, Steven; Sivasankar, Sanjeevi;  August 16, 1994
Methods of bonding optical structures, bonded optical structures, silylated bonded optical structures, and the like, are disclosed.


Top



Some links on this page may take you to non-federal websites. Their policies may differ from this site.