Short coherence length, doppler velocimetry system
First Claim
1. 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 first 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 which comprises at least one reflective surface;
means for altering an optical path length of the reference beam from the splitting means to a detector means at an alteration velocity, wherein the means for altering comprises means for translating the at least one reflective surface;
an interferometer means which includes a long coherence length radiation source having a second principal wavelength and the at least one reflective surface, the interferometer means producing an interferometer output;
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;
(b) for generating an interference signal; and
(c) for detecting the interferometer output and for transmitting an output interferometer signal to analyzer means;
wherein the analyzer means comprises means, in response to the output interferometer signal, for determining the alteration velocity from a central frequency of a frequency spectrum of the output interferometer signal and the second principal wavelength; and
the analyzer means further comprises 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 first principal wavelength.
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Accused Products
Abstract
Apparatus for measuring the speed of blood in blood vessels in biological samples, for example, in retinal blood vessels, which apparatus includes: (a) a source of a beam of radiation having a principal wavelength, which radiation is substantially spatially coherent and has a temporal coherence length which is less than 1 picosecond; (b) a beam splitter for splitting the beam into a sample beam and reference beam; (c) optical apparatus for directing the sample beam to an area within the biological sample; (d) a reflector for reflecting the reference beam; (e) a detector for detecting an interference between the sample beam reflected from the area and the reflected reference beam and for generating an interference signal; (f) apparatus for altering an optical path length of the reference beam from the beam splitter to the detector at an alteration velocity; and (g) an analyzer for analyzing the interference signal to determine the speed of the blood in the area from a shift of a central frequency of a frequency spectrum of the interference signal from a frequency determined from the alteration velocity and the principal wavelength.
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Citations
13 Claims
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1. 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:
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a source of a beam of radiation having a first 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 which comprises at least one reflective surface; means for altering an optical path length of the reference beam from the splitting means to a detector means at an alteration velocity, wherein the means for altering comprises means for translating the at least one reflective surface; an interferometer means which includes a long coherence length radiation source having a second principal wavelength and the at least one reflective surface, the interferometer means producing an interferometer output; 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;
(b) for generating an interference signal; and
(c) for detecting the interferometer output and for transmitting an output interferometer signal to analyzer means;wherein the analyzer means comprises means, in response to the output interferometer signal, for determining the alteration velocity from a central frequency of a frequency spectrum of the output interferometer signal and the second principal wavelength; and the analyzer means further comprises 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 first principal wavelength. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification