Phase-resolved optical coherence tomography and optical doppler tomography for imaging fluid flow in tissue with fast scanning speed and high velocity sensitivity

A method for phase-resolved optical tomography comprising:

• providing a source of at least partially coherent radiation through an interferometer, said at least partially coherent radiation characterized by a phase;
• phase modulating said radiation in said interferometer at a modulation frequency;
• scanning said sample with said source of at least partially coherent radiation through said interferometer in a sequence of pixel line scans, said sample having a fluid flow therein;
• changing said phase of said at least partially coherent radiation in response to said fluid flow at each pixel of each pixel line scan;
• detecting interference fringes of said radiation backscattered from said sample into said interferometer;
• processing said detected interference fringes to determine ODT phase signals of said detected backscattered interference fringes at each pixel of said pixel line scans to generate a corresponding rate of change of said phase at each pixel in a data window through the use of a Hilbert transformation at each pixel, and
• generating a tomographic image of the fluid flow in said sample from said rate of change of said phase at each pixel.

A method for phase-resolved optical tomography comprising:

• providing a source of at least partially coherent radiation through an interferometer with a reference arm, a sample arm and a detection arm, said at least partially coherent radiation characterized by a phase;
• phase modulating said radiation in said interferometer at a modulation frequency;
• scanning said sample with said source of at least partially coherent radiation through said interferometer in a sequence of pixel line scans, said sample having a fluid flow therein so that said phase of said at least partially coherent radiation is changed in response to said fluid flow at each pixel of each pixel line scan;
• providing circularly polarized reflected radiation from said reference arm;
• providing linearly polarized reflected radiation from said sample arm;
• combining said circularly polarized reflected radiation from said reference arm and said linearly polarized reflected radiation from said sample arm in a coupler;
• and
• splitting radiation from said coupler into two polarized beams in said detection arm with a polarizing beam splitter with an axis of polarization set at 45° to said linearly polarized reflected radiation from said sample arm,
• detecting interference fringes of said radiation backscattered from said sample into said interferometer in said two polarized beams in two corresponding detectors to generate two corresponding signals comprising in turn the real and imaginary parts of {tilde over (Γ)}ODT(t) so that said phase is directly measured;
• and
• generating a tomographic image of the fluid flow in said sample from said phase at each pixel.

An apparatus for phase-resolved optical tomography capable of simultaneously imaging fluid flow and morphology in sample with fast scanning speed and high velocity sensitivity comprising:

• an interferometer;
• a source of at least partially coherent radiation through coupled to said interferometer, said at least partially coherent radiation characterized by a phase;
• phase modulator coupled to said source to modulate said radiation in said interferometer at a modulation frequency;
• a scanner for scanning said sample with said source of at least partially coherent radiation through said interferometer in a sequence of pixel line scans, said sample having a fluid flow therein so that said phase of said at least partially coherent radiation is changed in response to said fluid flow at each pixel of each pixel line scan;
• a detector to detect interference fringes of said radiation backscattered from said sample into said interferometer;
• a processor to determine said corresponding phase at each pixel of said pixel line scans from said ODT phase signals of said detected backscattered interference fringes and to compare said phase between corresponding pixels in two line scans to generate a difference between said phase at said two corresponding pixels in two line scans whereby speckle is substantially reduced;
• and
• a display to generate a tomographic image of the fluid flow in said sample from said difference at each pixel.

An apparatus for phase-resolved optical tomography of a sample comprising:

• an interferometer
• a source of at least partially coherent radiation coupled to said interferometer, said at least partially coherent radiation characterized by a phase;
• a modulator for phase modulating said radiation in said interferometer at a modulation frequency;
• a scanner for scanning said sample with said source of at least partially coherent radiation through said interferometer in a sequence of pixel line scans, said sample having a fluid flow therein in which said phase of said at least partially coherent radiation is changed in response to said fluid flow at each pixel of each pixel line scan;
• a detector for detecting interference fringes of said radiation backscattered from said sample into said interferometer;
• a processor for processing said detected interference fringes to determine ODT phase signals of said detected backscattered interference fringes at each pixel of said pixel line scans to generate a corresponding rate of change of said phase at each pixel in a data window through the use of a Hilbert transformation at each pixel, and
• a display for generating a tomographic image of the fluid flow in said sample from said rate of change of said phase at each pixel.

An apparatus for phase-resolved optical tomography in a sample comprising:

• an interferometer with a reference arm, a sample arm and a detection arm;
• a source of at least partially coherent radiation coupled to said interferometer, said at least partially coherent radiation characterized by a phase;
• a modulator for phase modulating said radiation in said interferometer at a modulation frequency;
• a scanner for scanning said sample with said source of at least partially coherent radiation through said interferometer in a sequence of pixel line scans, said sample having a fluid flow therein so that said phase of said at least partially coherent radiation is changed in response to said fluid flow at each pixel of each pixel line scan;
• a circular polarizer for circularly polarizing reflected radiation from said reference arm;
• a linear polarizer for linearly polarized reflected radiation from said sample arm;
• a coupler for combining said circularly polarized reflected radiation from said reference arm and said linearly polarized reflected radiation from said sample arm;
• and
• a beam splitter for splitting radiation from said coupler into two polarized beams in said detection arm with a polarizing beam splitter with an axis of polarization set at 45° to said linearly polarized reflected radiation from said sample arm,
• two corresponding detectors for detecting interference fringes of said radiation backscattered from said sample into said interferometer in said two polarized beams to generate two corresponding signals comprising in turn the real and imaginary parts of {tilde over (Γ)}ODT(t) so that said phase is directly measured;
• and
• a display for generating a tomographic image of the fluid flow in said sample from said phase at each pixel.

A method for optical tomography comprising:

• providing a source of at least partially coherent radiation through an interferometer, said at least partially coherent radiation characterized by a phase;
• providing a rapid-scanning optical delay line and an electro-optic modulator coupled to said rapid-scanning optical delay line;
• phase modulating said radiation in said interferometer by means of said rapid-scanning optical delay line and electro-optic modulator in combination at a modulation frequency with a stable phase modulation;
• scanning said sample with said source of at least partially coherent radiation through said interferometer;
• detecting interference fringes of said radiation backscattered from said sample into said interferometer.

An apparatus for optical tomography comprising:

• an interferometer;
• a source of at least partially coherent radiation coupled to said interferometer, said at least partially coherent radiation characterized by a phase;
• a rapid-scanning optical delay line;
• an electro-optic modulator coupled to said rapid-scanning optical delay line to modulate said radiation in said interferometer at a modulation frequency with a stable phase modulation;
• a scanner for scanning said sample with said source of at least partially coherent radiation through said interferometer;
• and
• a detector to detect interference fringes of said radiation backscattered from said sample into said interferometer.