Swapan K Gayen

6665557, Dec 16, 2003

Jun 20, 2000

09/597505

Robert R. Alfano - Bronx NY
Swapan Kumar Gayen - Marlboro NJ
Manuel E. Zevallos - Jackson Heights NY

The Research Foundation of City College of New York - New York NY

A61B 600

600473, 600475

Method and apparatus for imaging objects in turbid media. In one embodiment, the method comprises illuminating at least a portion of the turbid medium with substantially monochromatic light of at least two wavelengths in the 600-1500 nm spectral range. A first of the at least two wavelengths is equal to a resonance wavelength for an optical property of an object in the illuminated portion of the turbid medium but is not equal to a resonance wavelength for the turbid medium. A second of the at least two wavelengths is not equal to a resonance wavelength for either the object or the turbid medium. Light emergent from the turbid medium following each of the foregoing illuminations comprises a ballistic component, a snake component and a diffuse component. A direct shadowgram image may be obtained by preferentially passing from the emergent light, following each illumination. the ballistic and snake components thereof and detecting the preferentially passed light.

7106972, Sep 12, 2006

Apr 4, 2002

10/116194

Robert R. Alfano - Bronx NY, US
Jin Pin Ying - Fresh Meadow Lane NY, US
Swapan K. Gayen - Marlboro NJ, US
Wei Cai - Bronx NY, US

The Research Foundation of the City University of New York - New York NY

H04B 10/00

398158, 398159, 398119

A method of improving a signal-to-noise (S/N) ratio for a light signal transmitted by wireless optical communication through adverse environmental conditions, the light signal including a snake component and a ballistic component for carrying coded information, and a diffusive component that adds to background noise, the method comprising the steps of: encoding information to be transmitted by the light signal, wherein the light signal is one of a serial train of code pulses or a modulated light beam; selecting an appropriate wavelength for the encoded light signal; transmitting the encoded light signal though the adverse environmental conditions; receiving the encoded light signal; sorting the received encoded light signal to preferentially select the information carrying components and reduce the diffusive component; and detecting the sorted encoded light signal with a photo-detector.

7826878, Nov 2, 2010

Dec 7, 2005

11/296831

Robert R. Alfano - Bronx NY, US
Min Xu - Woodside NY, US
Mohammed Alrubaiee - New York NY, US
Swapan Kumar Gayen - Marlboro NJ, US

Research Foundation of City University of New York - New York NY

A61B 5/00

600310, 382128

Disclosed is a system and a method for detecting the presence of one or more objects in a turbid medium, the method including: illuminating at least a portion of the turbid medium with incident light having at least one wavelength which interacts with the one or more objects contained in the turbid medium differently than the incident light interacts with the turbid medium; measuring light that emerges from the turbid medium; and detecting and locating the one or more objects using Independent Component Analysis (ICA) of the emergent light from the turbid medium. The present invention is useful for medical applications, such as for finding and locating, a tumor(s) in body organs, or excised tissues. Moreover, the present invention can be used to locate objects in obscuring medium, such as, mines in shallow coastal water, a plane in fog, military targets under fog, smoke or cloud cover.

49320319, Jun 5, 1990

Sep 26, 1989

7/248749

Robert R. Alfano - Bronx NY
Vladimir Petricevic - New York NY
Swapan Gayen - Bronx NY

H01S 316

372 41

A laser system in which the laser medium is a single crystal of Cr. sub. 3+ :Mg. sub. 2 SiO. sub. 4 is disclosed. In one embodiment, the system comprises a single crystal of chromium doped forsterite and a cavity which includes a pair of 30 cm. radius mirror having high transmission at 543 nm (the pump wavelength) and high reflectivity in the 1150-1350 nm range. Room temperature vibronic pulsed laser action is obtained with this cavity. Laser action has been observed at 1235 nm and a bandwidth of 25 nm. The wavelength range is suitable for transmission through optical fibers and is useful in laser ranging and remote sensing. Because of the ultrawide fluorescence bandwidth and a 15 fluoroescence lifetime the system is suitable for high intensity, tunable, cw, Q switched mode locked operation. In the mode locked operation pulses as short as 10-500 femtosecond may be generated. A number of different embodiments of the invention are described.

61085766, Aug 22, 2000

Feb 10, 1997

8/797163

Robert R. Alfano - Bronx NY
Wei Cai - Bronx NY
Swapan K. Gayen - Marlboro NJ

The Research Foundation of City College of New York - New York NY

A61B 600

600476

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r. sub. s and r. sub. d, at time t, to position r,. LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X. sub. j that we are trying to determine:. LAMBDA. sub. ij =. lambda. sub. j. delta. sub. ij with. lambda. sub. j =/

57216320, Feb 24, 1998

Aug 30, 1995

8/521195

Richard I. Billmers - Bensalem PA
Martin F. Squicciarini - Lansdale PA
Swapan K. Gayen - Marlboro NJ

The United States of America as represented by the Secretary of the Navy - Washington DC

G02F 103

359252

An excited state polarization altering optical filter includes a vapor cell having a population of electrons with a plurality of energy levels that receive light and transmit light according to the received light. A first pulsed dye laser applies a beam of light by way of a circular polarizer to provide a first beam of light having a first polarization to the vapor cell. The first beam of light causes transitions of the electrons from one energy level to another energy level. A second pulsed dye laser applies a second beam of light with a second, differing, linear polarization to the vapor cell. The vapor cell differentially transmits the first and second beams of light in accordance with the differing polarizations. A delay path is provided for delaying the second beam of light before the second beam of light is applied to the vapor cell. The delay path is tuned by adjusting the length.

20140114181, Apr 24, 2014

Oct 22, 2013

14/060221

- New York NY, US
Wei Cai - Bronx NY, US
Swapan K. Gayen - Marlboro NJ, US

A61B 5/00

600425

A time reversal optical tomography (TROT) method for near-infrared (NM) diffuse optical imaging of targets embedded in a highly scattering turbid medium is presented. TROT combines the basic symmetry of time reversal invariance and subspace-based signal processing for retrieval of target location. The efficacy of TROT is tested using simulated data and data obtained from NIR imaging experiments on absorptive, scattering and fluorescent targets embedded in Intralipid-20% suspension in water, as turbid medium, as well as, a realistic cancerous model breast assembled using ex vivo human breast tissues with two embedded tumors. The results demonstrate the potential of TROT for detecting and locating small targets in a turbid medium, such as, breast tumors in early stages of growth.