US5501226A — Short coherence length, doppler velocimetry system

Claim 1

Independent Claim 219 words

Apparatus for measuring a profile of speed of blood, wherein the speed is parallel or antiparallel to the direction of a sample beam, the profile being across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which apparatus comprises: a source of a beam of radiation having a principal wavelength, which beam of radiation is substantially spatially coherent and has a temporal coherence length which is less than 1 picosecond; means for splitting the beam into the sample beam and a reference beam; means for reflecting the reference beam; means for altering an optical path length of the reference beam from the splitting means to a detector means at an alteration velocity; means for directing the sample beam within the biological sample to pass through the blood vessel; wherein the detector means comprises means: (a) for detecting interferences between reflections of the sample beam from matter in the sample including matter situated across the blood vessel and reflections of the reference beam from the reflecting means and (b) for generating an interference signal; analyzer means for analyzing the interference signal to determine the profile of the speed of the blood from an analysis of frequency spectra of time segments of the interference signal, the alteration velocity in the time segments, and the principal wavelength.

Claim 2

Dependent Claim 219 words

Apparatus for measuring a profile of speed of blood, wherein the speed is parallel or antiparallel to the direction of a sample beam, the profile being across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which apparatus comprises: a source of a beam of radiation having a principal wavelength, which beam of radiation is substantially spatially coherent and has a temporal coherence length which is less than 1 picosecond; means for splitting the beam into the sample beam and a reference beam; means for reflecting the reference beam; means for altering an optical path length of the reference beam from the splitting means to a detector means at an alteration velocity; means for directing the sample beam within the biological sample to pass through the blood vessel; wherein the detector means comprises means: (a) for detecting interferences between reflections of the sample beam from matter in the sample including matter situated across the blood vessel and reflections of the reference beam from the reflecting means and (b) for generating an interference signal; analyzer means for analyzing the interference signal to determine the profile of the speed of the blood from an analysis of frequency spectra of time segments of the interference signal, the alteration velocity in the time segments, and the principal wavelength.

Claim 3

Dependent Claim 55 words

The apparatus of claim 1 wherein the analyzer means comprises means for determining, within a time segment, the speed of blood in a portion of the blood vessel from a central frequency of a frequency spectrum of the interference signal in the time segment, the alteration velocity in the time segment, and the principal wavelength.

Claim 4

Dependent Claim 55 words

The apparatus of claim 2 wherein the analyzer means further comprises means for determining, within the time segment, the speed of blood in the portion of the blood vessel from a width of the frequency spectrum of the interference signal in the time segment, the alteration velocity, the principal wavelength, and the temporal coherence length.

Claim 5

Dependent Claim 30 words

The apparatus of claim 3 wherein the analyzer means further comprises means for identifying the time segment which includes means for detecting maxima of an envelope of the interference signal.

Claim 6

Dependent Claim 38 words

The apparatus of claim 4 wherein the means for determining further comprises means for determining the profile of speed of blood from the interference signal generated during a single pass of the sample beam through the blood vessel.

Claim 7

Dependent Claim 37 words

The apparatus of claim 4 wherein means for determining further comprises means for determining the profile of speed of blood from interference signals generated during a multiplicity of passes of the sample beam through the blood vessel.

Claim 8

Dependent Claim 30 words

The apparatus of claim 1 wherein the source of the beam of radiation is a superluminescent light emitting diode, wherein the beam of radiation is focused through a pinhole aperture.

Claim 9

Dependent Claim 32 words

The apparatus of claim 1 wherein the source of the beam of radiation is a superluminescent light emitting diode, wherein the beam of radiation is coupled into a single mode optical fiber.

Claim 10

Dependent Claim 32 words

The apparatus of claim 1 wherein the means for reflecting the reference beam comprises at least one reflective surface and the means for altering comprises means for translating the means for reflecting.

Claim 11

Dependent Claim 26 words

The apparatus of claim 9 which further comprises means for determining the alteration velocity and for applying the alteration velocity as input to the analyzer means.

Claim 12

Dependent Claim 36 words

The apparatus of claim 10 wherein the means for translating outputs a position signal to the means for determining and the means for determining comprises means for differentiating the position signal to determine the alteration velocity.

Claim 13

Dependent Claim 67 words

The apparatus of claim 1 wherein the beam is coupled into an optical fiber and at least one portion of a path of travel within the apparatus of the sample beam and the reflections of the sample beam is comprised of an optical fiber and at least one portion of a path of travel within the apparatus of the reference beam is comprised of an optical fiber.

Claim 14

Dependent Claim 42 words

The apparatus of claim 12 wherein the means for reflecting comprises means for movement in fixed increments and the means for altering comprises one or more acousto-optic modulators attached to the optical fiber in the path of travel of the reference beam.

Claim 15

Dependent Claim 19 words

The apparatus of claim 13 wherein the means for altering further comprises means for translating the means for reflecting.

Claim 16

Dependent Claim 42 words

The apparatus of claim 12 wherein the means for reflecting comprises means for movement in fixed increments and the means for altering comprises one or more piezo-electric transducers attached to the optical fiber in the path of travel of the reference beam.

Claim 17

Dependent Claim 19 words

The apparatus of claim 15 wherein the means for altering further comprises means for translating the means for reflecting.

Claim 18

Dependent Claim 24 words

The apparatus of claim 1 wherein the length of the time segments is proportional to the temporal coherence length divided by the alteration velocity.

Claim 19

Dependent Claim 219 words

Method for measuring a profile of absolute value of velocity of blood across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which method comprises the steps of: generating a sample beam having a principal wavelength from a short coherence length Michelson interferometer having a reference beam whose reference beam path is varied at an alteration velocity; aiming the sample beam at a wall of the blood vessel; scanning the sample beam over the blood vessel in a first direction by varying the reference beam path at the alteration velocity and detecting an interference signal produced by an interference between reflections of the sample beam and the reference beam; determining a first position of a first wall and a first position of a second wall from the interference signal; determining components of velocity of the blood parallel or antiparallel to a direction of the sample beam from the interference signal by analyzing frequency spectra of time segments of the interference signal; scanning the sample beam in a second direction to determine a second position of the second wall; determining an angle of the first direction with respect to a direction of the blood vessel from the positions; and determining the absolute velocity profile of the blood from the components of velocity and the angle.

Claim 20

Dependent Claim 219 words

Method for measuring a profile of absolute value of velocity of blood across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which method comprises the steps of: generating a sample beam having a principal wavelength from a short coherence length Michelson interferometer having a reference beam whose reference beam path is varied at an alteration velocity; aiming the sample beam at a wall of the blood vessel; scanning the sample beam over the blood vessel in a first direction by varying the reference beam path at the alteration velocity and detecting an interference signal produced by an interference between reflections of the sample beam and the reference beam; determining a first position of a first wall and a first position of a second wall from the interference signal; determining components of velocity of the blood parallel or antiparallel to a direction of the sample beam from the interference signal by analyzing frequency spectra of time segments of the interference signal; scanning the sample beam in a second direction to determine a second position of the second wall; determining an angle of the first direction with respect to a direction of the blood vessel from the positions; and determining the absolute velocity profile of the blood from the components of velocity and the angle.

Claim 21

Dependent Claim 226 words

Method for measuring a profile of absolute value of velocity of blood across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which method comprises the steps of: generating a sample beam having a principal wavelength from a short coherence length Michelson interferometer having a reference beam whose reference beam path is varied at an alteration velocity; aiming the sample beam at a wall of the blood vessel; scanning the sample beam over the blood vessel in a first direction by varying the reference beam path at the alteration velocity and detecting an interference signal produced by an interference between reflections of the sample beam and the reference beam; determining a first position of a first wall from the interference signal; determining components of velocity of the blood parallel or antiparallel to a direction of the sample beam and a first position of a maximum of velocity from the interference signal by analyzing frequency spectra of time segments of the interference signal; scanning the sample beam in a second direction to determine a second position of a maximum of velocity; determining an angle of the first direction with respect to a direction of the blood vessel from the first position and the second position; and determining the absolute velocity profile of the blood from the components of velocity and the angle.

Claim 22

Dependent Claim 226 words

Method for measuring a profile of absolute value of velocity of blood across a blood vessel in a biological sample, in particular, in a retinal blood vessel, which method comprises the steps of: generating a sample beam having a principal wavelength from a short coherence length Michelson interferometer having a reference beam whose reference beam path is varied at an alteration velocity; aiming the sample beam at a wall of the blood vessel; scanning the sample beam over the blood vessel in a first direction by varying the reference beam path at the alteration velocity and detecting an interference signal produced by an interference between reflections of the sample beam and the reference beam; determining a first position of a first wall from the interference signal; determining components of velocity of the blood parallel or antiparallel to a direction of the sample beam and a first position of a maximum of velocity from the interference signal by analyzing frequency spectra of time segments of the interference signal; scanning the sample beam in a second direction to determine a second position of a maximum of velocity; determining an angle of the first direction with respect to a direction of the blood vessel from the first position and the second position; and determining the absolute velocity profile of the blood from the components of velocity and the angle.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-03-26	1999-09-25	2000-03-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-03-26	2003-09-25	2004-03-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-03-26	2007-09-25	2008-03-26	$7700.00	Window Closed / Lapsed

Short coherence length, doppler velocimetry system

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