Abstract: A system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating. A broad band light source produces light having a short coherence length. A beamsplitter splits the light into a signal beam and a reference beam. A reference mirror is disposed to receive the reference beam. A lens brings the signal beam to focus on the sample. A diffraction grating receives reflections from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that a positive diffraction order from one of the reflections and a negative diffraction order from the other one of the reflections and a negative diffraction order from the other one of the reflections propagate along a common path.

Abstract: 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.

Abstract: A photon-mediated technique for introducing biological materials into cells and/or cellular components. The technique may be used to introduce nucleic acids, such as DNA and RNA, proteins or other biological materials into mammalian cells (as well as into other animal and plant cells), which materials may then flow into the nuclei of the cells. The technique uses picosecond or femtosecond light pulses propagating in the UV, visible and near infrared wavelength regions with powers on the order of 1×1010 W/cm2. In practice, the desired biological materials are coated on the end of the inner core of a single mode fiber or the ring core of a fiber in a fiber array. Each fiber is sized to correspond to one cell, with the core size ranging from 2&mgr; to 10&mgr;, and the cladding ranging from 10&mgr; to 30&mgr;. The laser pulse travels through a fiber core which is coated with the materials and ablates a portion of a targeted cell or cellular component membrane.

Abstract: A system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating. A broad band light source produces light having a short coherence length. A beamsplitter splits the light into a signal beam and a reference beam. A reference mirror is disposed to receive the reference beam. A lens brings the signal beam to focus on the sample. A diffraction grating receives reflections from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that a positive diffraction order from one of the reflections and a negative diffraction order from the other one of the reflections and a negative diffraction order from the other one of the reflections propagate along a common path.

Abstract: An apparatus utilizing non-linear optical signals for use in constructing a three-dimensional tomographic map of an in vivo biological tissue for medical disease detection purposes. In one embodiment, said apparatus comprises a stage for supporting the in vivo biological tissue; a laser for illuminating the in vivo biological tissue with a focused beam of laser light, the light emerging from the in vivo biological tissue comprising fundamental light, harmonic wave light, and fluorescence due to multi-photon excitation; a filter for selectively passing only at least one of the harmonic wave light and the fluorescence; one or more detectors for individually detecting each of the harmonic wave light and the fluorescence selectively passed; and a mechanism for moving the laser relative to the stage in x, y and z directions.

Abstract: 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, <nn>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 =<nn>/<.DELTA.Xj.DELTA.Xj>Y is the data collected at the detectors, and X.sup.

Abstract: A method of detecting cancer or precancerous conditions in a tissue or cell using fluorescence excitation spectroscopy. According to one embodiment of the method, a tissue is tested for cancer or a precancerous condition by exciting the tissue with substantially monochromatic light at 268 nm and then at 289 nm, with the resultant native fluorescence emitted from the tissue following each excitation being measured. A ratio of the fluorescence intensities, e.g., I.sub.289 /I.sub.268, is then calculated. If I.sub.289 /I.sub.268 is greater than 1.5, the tissue is cancerous or precancerous whereas if I.sub.289 /I.sub.268 is less than 1.5, the tissue is not cancerous or precancerous.

Abstract: A method and apparatus for examining a cell smear for the purpose of detecting the presence of cancerous and precancerous cells located therein. In a preferred embodiment, the method comprises illuminating at least a portion of the cell smear with light of a first wavelength, whereby native fluorescence is emitted therefrom. Next, the intensity of native fluorescence emitted from the illuminated area is measured at a second wavelength and at a third wavelength as a function of location within the illuminated area. The first, second and third wavelengths are chosen so that the ratio of fluorescence intensities at the second and third wavelengths is indicative of a carcinomatous condition. Next, the ratio of intensities measured at the second and third wavelengths is determined to obtain a value for each location within the illuminated area. Finally, a map is generated of all the cells present within the illuminated area using the calculated values.

Abstract: Method and apparatus for examining subcutaneous tissues inside organs of the body. The method comprises the steps of (a) providing an optic probe positioning assembly comprising a solid needle and a hollow tube, the solid needle being sheathed inside the hollow tube; (b) subcutaneously inserting the positioning assembly into a tissue sample to be examined; (c) removing the solid needle from the tissue sample, leaving the hollow tube in place in the tissue; (d) then, inserting an optic probe through the hollow tube into proximity with the tissue sample; (e) optically determining the condition of the tissue sample using the optic probe; (f) after the optically determining step, removing the optic probe from the hollow tube; (g) then, inserting a biopsy needle into the hollow tube; (h) then, excising at least a portion of the tissue sample; and (i) then, removing the biopsy needle and the excised tissue sample from the hollow tube.

Abstract: A system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating. A broad band light source produces light having a short coherence length. A beamsplitter splits the light into a signal beam and a reference beam. A reference mirror is disposed to receive the reference beam. A lens brings the signal beam to focus on the sample. A diffraction grating receives a reflection from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that the positive and negative first or second or higher diffraction orders from said reflections received propagate along a normal to said diffraction grating.

Abstract: 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: ##EQU1## 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, <nn> 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 =<nn>/<.DELTA.Xj.DELTA.Xj>Y is the data collected at the detectors, and X.sup.

Abstract: A method and apparatus for imaging objects based upon the polarization or depolarization of light. According to one embodiment, there is provided a method for imaging the surface of a turbid medium, the method comprising the steps of: (a) illuminating the surface of the turbid medium with light, whereby light is backscattered from the illuminated surface of the turbid medium; (b) detecting a pair of complementary polarization components of the backscattered light; and (c) forming an image of the illuminated surface using the pair of complementary polarization components. Preferably, the illuminating light is polarized (e.g., linearly polarized, circularly polarized, elliptically polarized).

Abstract: A method and apparatus for imaging objects based upon the polarization or depolarization of light. According to one embodiment, there is provided a method for imaging the surface of a turbid medium, the method comprising the steps of: (a) illuminating the surface of the turbid medium with light, whereby light is backscattered from the illuminated surface of the turbid medium; (b) detecting a pair of complementary polarization components of the backscattered light; and (c) forming an image of the illuminated surface using the pair of complementary polarization components. Preferably, the illuminating light is polarized (e.g., linearly polarized, circularly polarized, elliptically polarized).

Abstract: A method for detecting the presence of one or more calcifications within a portion of a turbid medium, such as a breast tissue. According to one aspect, the method involves illuminating at least a portion of the turbid medium with light, whereby light emerges from the turbid medium consisting of a ballistic component, a snake-like component and a diffuse component, temporally and/or spatially gating the emergent light to preferentially pass the ballistic and/or snake-like components, using the temporally and/or spatially gated light to form an image of the illuminated portion of the turbid medium, and examining the image for the presence of one or more calcifications. Wavelength difference images may also be used to highlight tumors and calcification regions.

Abstract: A method for detecting cancerous tissue using optical spectroscopy and Fourier analysis. According to a preferred embodiment, a tissue sample is illuminated with light at a wavelength of approximately 300 nm. Next, a fluorescence emission spectrum for the tissue sample is obtained by measuring the resultant fluorescence from the tissue sample over the spectral region from approximately 320 nm to approximately 580 nm. The phase and amplitude for the first three Fourier transform harmonics are then determined. The phase and amplitude determinations for one or more of the three harmonics are then compared to appropriate standards obtained from cancerous and non-cancerous tissue samples. The accuracy of the method can be improved further by comparing the phase and amplitude calculations for at least two harmonics.

Abstract: A method and apparatus for imaging and/or characterizing a tissue based upon the extent to which initially polarized light maintains its polarization after propagating through the tissue.

Abstract: A method for amplifying a signal pulse of laser light. Preferably, the method is used to amplify 1.3 .mu.m and/or 1.55 .mu.m signal pulses emitted from any 1.3 .mu.m or 1.55 .mu.m signal source, the method comprising providing an amplifying medium, the amplifying medium comprising an elongated core and a light-retaining outer structure surrounding the elongated core. The elongated core preferably comprises a plurality of Cr.sup.4+ -doped crystalline particles capable of lasing at 1.3 .mu.m and/or 1.55 .mu.m and preferably having a size of approximately 0.05 .mu.m to 500 .mu.m. The crystalline particles are dispersed within a non-gaseous medium, the non-gaseous medium having an index of refraction that substantially matches that of the crystalline particles.

Abstract: A method and apparatus for evaluating the composition of an oil sample. The method and apparatus are premised on the discovery that spectral differences can be observed in the luminescence, excitation, light scattering and absorption spectra in the near UV, visible and near IR regions for various crude oil components, such as asphaltenes, deasphalted crude oil and organic solid residues. Accordingly, in one preferred embodiment the method comprises illuminating an oil sample with light of a suitable excitation wavelength, measuring the resultant fluorescence therefrom and comparing the resultant fluorescence to appropriate standards derived from known components of crude oil.

Abstract: A method of forming 2 dimensional image of a translucent object in or behind a turbid medium. In one embodiment, the method comprises the steps of illuminating the translucent object through one side of the turbid medium with an ultrafast pulse of light, the light emergent from the opposite side of the turbid medium consisting of a ballistic component, a snake-like component and a diffuse component. The emergent light is then temporally and spatially gated to preferentially pass the ballistic component and the snake-like component. Preferably, the temporal and spatial gating is achieved by positioning the Kerr cell of an optical Kerr gate at the 2F spectral plane of a 4F Kerr-Fourier imaging system. At the appropriate time, that portion of the Kerr cell located at the focal point of the 2F spectral plane is gated open, allowing predominantly ballistic and snake-like components of the transilluminated light to pass therethrough.

Abstract: An optical streak camera includes an optical collimator, an all optical deflector, a detector and a display.