Danh D Tran

US Patent:

6636111, Oct 21, 2003

Filed:

Jul 26, 2002

Appl. No.:

10/207446

Inventors:

William H. Gross - Sunnyvale CA
Danh T. Tran - Fremont CA

Assignee:

Linear Technology Corporation - Milpitas CA

International Classification:

H03L 500

US Classification:

327589, 327307, 330261, 330269

Abstract:

An electronic circuit to cancel the input bias currents of a differential amplifier over most of the common-mode input voltage range is provided. The circuit includes an arrangement of transistors, current mirror and current sources to track the input bias currents of the differential amplifier even when the common-mode voltage is within at least 0. 2 volts of the supply rail voltage level. The input bias cancellation currents are generated by tracking the input bias currents and injected into the differential amplifier inputs to cancel the input bias currents. The circuit includes a bootstrap loop to track the input bias currents when the common-mode voltage fluctuates.

US Patent:

20040198581, Oct 7, 2004

Filed:

Apr 1, 2004

Appl. No.:

10/814193

Inventors:

Danh Tran - Potomac MD, US

Assignee:

Infrared Fiber Systems, Inc. - Silver Spring MD

International Classification:

C03C003/23
C03C003/247

US Classification:

501/043000, 501/044000

Abstract:

Maximizing the glass forming ability of low metal-phosphate content fluoride-based glasses allows the fabrication of large-size “crystal-free” HEL windows. This involves the addition of glass stabilizer oxides such as SiO, TiO, Al2O. In situ quenching is used to fabricate large-scale HEL windows substantially free of crystals, bubbles and striation.

US Patent:

20090090135, Apr 9, 2009

Filed:

Sep 29, 2008

Appl. No.:

12/240525

Inventors:

Danh C. Tran - Potomac MD, US

Assignee:

INFRARED FOCAL SYSTEMS, INC. - Silver Spring MD

International Classification:

C03B 19/02

US Classification:

65 991

Abstract:

High optical quality glass windows, particularly of low melting and low viscosity glasses and substantially free of defects, particularly adapted for high energy laser applications, are made by stirring the molten glass during cooling without the use of a mechanical stirrer within the glass, by rotating the mold or crucible in which the glass is cooling, using a motion which is not entirely a circular and rotary motion.

US Patent:

43338470, Jun 8, 1982

Filed:

Aug 10, 1979

Appl. No.:

6/065752

Inventors:

Danh C. Tran - Rockville MD
Pedro B. Macedo - Bethesda MD
Joseph H. Simmons - Bethesda MD
Catherine J. Simmons - Bethesda MD
Nicholas Lagakos - Silver Spring MD

International Classification:

G21F 916

US Classification:

252629

Abstract:

This invention relates to the immobilization of toxic, e. g. , radioactive materials, internally in a silicate glass or silica gel matrix for extremely long periods of time. Toxic materials, such as radioactive wastes containing radioactive anions, and in some cases cations, which may be in the form of liquids, or solids dissolved or dispersed in liquids or gases, are internally incorporated into a glass matrix, having hydrous organofunctionalsiloxy groups, e. g. , hydrous aminoalkylsiloxy or carboxyorganosiloxy, bonded to silicon atoms of said glass and/or hydrous polyvalent metals bonded to silicon atoms of said glass through divalent oxygen linkages or otherwise immobilized therein, by a process which involves the ion exchange of said toxic, radioactive anions with hydroxyl groups attached to said organofunctionalsiloxy groups or with hydroxyl groups attached to the hydrous polyvalent metal. Thereafter, the resulting glass now characterized by a distribution of internally bonded or immobilized, toxic, radioactive anions can be packaged in suitable containers, and disposed of as by burial, and/or they can be sintered to collapse the pores thereof prior to disposal or for producing useful radiation sources. The porous glass or a porous silica gel having said silicon-bonded organofunctionalsiloxy groups and/or said hydrous polyvalent metal oxy groups, the pores of said glass or silica gel remaining open and uncollapsed, can be used advantageously as a backfill for an underground radioactive waste burial site and as overpack in the waste disposal container.

US Patent:

50551205, Oct 8, 1991

Filed:

Mar 20, 1990

Appl. No.:

7/498453

Inventors:

Danh C. Tran - Bethesda MD
Reza Mossadegh - Silver Spring MD
Nicholas Garito - Fairfax VA
Mohamad Farid - Silver Spring MD

Assignee:

Infrared Fiber Systems, Inc. - Silver Spring MD

International Classification:

C03B 37027
C03B 37012

US Classification:

65 311

Abstract:

Improved fluoride glass optical fibers are produced by a process introducing several improvements in the production of fluoride glass preforms and the drawing of fibers therefrom. Reduced bubble formation and crystallization are obtained by vertically spinning a fluoride glass melt within a glass cladding tube at a high rotational speed, or alternatively, pouring a flouride glass core melt into a cladding tube while slowly raising the mold from an inclined position to a vertical position, or alternatively, introducing a core tube inside a cladding tube. The production of fibers is enhanced if at least one production phase, i. e. , preform formation or fiber drawing, is conducted in an atmosphere containing reactive gases that scavenge molecules that could otherwise react with, hydrolyze and oxidize the fluoride glass. The disclosure also describes several devices uniquely useful in the process of the present invention. In another aspect of the present invention, fluoride glass fibers may be clad with a fluoropolymer which is coated with a polymerizable resin.

US Patent:

58091998, Sep 15, 1998

Filed:

Sep 20, 1996

Appl. No.:

8/717099

Inventors:

Danh Tran - Bethesda MD

Assignee:

Infrared Fiber Systems, Inc. - Silver Spring MD

International Classification:

G02B 600

US Classification:

385141

Abstract:

A biocompatible optical fiber tip derived from fluorophosphate glasses whose composition includes P--O compounds, AlF. sub. 3, alkali-earth fluorides, and/or alkali fluorides, and lanthanides fluoride is used with a medical laser to transmit power for surgical applications.

US Patent:

43127746, Jan 26, 1982

Filed:

Apr 30, 1979

Appl. No.:

6/034567

Inventors:

Pedro B. Macedo - Bethesda MD
Catherine J. Simmons - Bethesda MD
Danh C. Tran - Rockville MD
Nicholas Lagakos - Silver Spring MD
Joseph Simmons - Bethesda MD

International Classification:

G21F 916

US Classification:

252629

Abstract:

This invention relates to the immobilization of toxic materials, e. g. , radioactive materials, in glass for extremely long periods of time. Toxic materials, such as radioactive wastes, which may be in the form of liquids, or solids dissolved or dispersed in liquids or gases, are deposited in a glass container which is heated to evaporate off non-radioactive volatile materials, if present; to decompose salts, such as nitrates, if any, and to drive off volatile non-radioactive decomposition products, and then to collapse the walls of said container on said radwaste and seal the container and immobilize the contained radwaste, and then burying the resulting product underground or at sea. In another embodiment, the glass container also contains glass particles, e. g. , spheres or granules, on which the radwaste solids are deposited.

US Patent:

50455079, Sep 3, 1991

Filed:

Jan 22, 1990

Appl. No.:

7/468300

Inventors:

Danh Tran - Bethesda MD

Assignee:

Infrared Fiber Systems, Inc. - Silver Spring MD

International Classification:

C03C 332

US Classification:

501 40

Abstract:

A process for producing high quality optical glass from fluoride glasses comprising preparing a melt of the glass and then cooling the melt in-situ inside the melt crucible. The in-situ quenching technique can be improved by narrowing the temperature range between the liquidus temperature and the glass transition temperature of the glass. The stability of the fluoride glass can be increased and the liquidus temperature of the glass can be lowered by doping the glass with a chloride dopant. Thorium tetrafluoride can be added to the chloride-doped glass in order to increase the chemical stability of the glass.