# US 10,871,503 B1 · Methods for depth estimation in laser speckle imaging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,503 B1 - Document ID: US10871503B1 - Status: Granted - Kind: B1 - Application number: 15/953,222 - Filed: 2018-04-13 - Granted: 2020-12-22 - Earliest claimed: 2015-05-26 - Assignees: Verily Life Sciences LLC - Applicants: Verily Life Sciences LLC - Inventors: Andrew Homyk; Jason Donald Thompson - Web page: https://patentgrep.com/patent/US10871503B1 ## CPC - G01P 5/26: by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave - A61B 5/0075: {by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence)} - A61B 5/0261: {using optical means, e.g. infrared light} - G01N 11/02: by measuring flow of the material - G01N 21/53: within a flowing fluid, e.g. smoke - G01S 7/499: using polarisation effects - G01S 17/46: Indirect determination of position data - G01S 17/50: Systems of measurement based on relative movement of target - G01S 17/88: Lidar systems specially adapted for specific applications - A61B 5/02042: {Determining blood loss or bleeding, e.g. during a surgical procedure} - A61B 5/02055: {Simultaneously evaluating both cardiovascular condition and temperature} - A61B 5/489: {Blood vessels} - A61B 5/681: {Wristwatch-type devices} - A61B 5/7239: {using differentiation including higher order derivatives} - G01N 2011/008: {optical properties} - G01N 2201/0612: Laser diodes - G01S 7/4815: {using multiple transmitters} - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract Systems and methods are provided for detecting the depth, flow rate, and other properties of regions of blood flow in biological tissue by illuminating the biological tissue with beams of coherent light and detecting responsively emitted light. This includes detecting lights emitted from the tissue having a plurality of respective different exposure times. The relationship between the intensity of the received light and the exposure times is determined and used to determine the depth, flow velocity, or other properties of regions of flow within the biological tissue. This can include determining a spatial and/or temporal contrast of the received light intensity. Determining the depth of a region of flow can include comparing determined properties of light received from the tissue at two different polarizations. Determining the depth of a region of flow can include comparing determined properties of light received from the tissue at two different locations. ## Claims ### Claim 1 A device comprising: a light source; at least one light sensor; and a controller, wherein the controller comprises a computing device programmed to perform operations comprising: during each of a plurality of time periods, wherein each time period is associated with a respective exposure time of a set of exposure times: emitting, by the light source, a beam of polarized coherent illumination into a biological tissue; detecting, using the at least one light sensor, an intensity of light of a first polarization received from a portion of the biological tissue during an exposure time; detecting, using the at least one light sensor, an intensity of light of a second polarization received from the portion of the biological tissue during the exposure time; determining, for each exposure time in the set of exposure times, a first contrast value and a second contrast value, wherein determining a first contrast value for a given exposure time comprises determining an amount of variation between at least two intensities of light of the first polarization detected during at least two time periods associated with the given exposure time, and wherein determining a second contrast value for the given exposure time comprises determining an amount of variation between at least two intensities of light of the second polarization detected during at least two time periods associated with the given exposure time; and determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values. ### Claim 2 (depends on 1) The device of claim 1, further comprising: an endoscopic probe configured to be inserted into a body cavity, wherein the light source is configured to emit light from the endoscopic probe, and wherein the at least one light sensor is configured to detect light received from the biological tissue via the endoscopic probe. ### Claim 3 (depends on 1) The device of claim 1, wherein the operations further comprise: determining a flow velocity within the region of flow as a function of the determined first contrast values. ### Claim 4 (depends on 3) The device of claim 3, wherein the determined flow velocity is a flow velocity of blood cells in the region of flow. ### Claim 5 (depends on 3) The device of claim 3, wherein determining a flow velocity within the region of flow as a function of the determined first contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; and using the determined exposure time to determine a flow velocity within the region of flow. ### Claim 6 (depends on 1) The device of claim 1, wherein the operations further comprise: during each of the plurality of time periods: detecting, using the at least one light sensor, an intensity of light of the first polarization received from a further portion of the biological tissue during an exposure time; and detecting, using the at least one light sensor, an intensity of light of the second polarization received from the further portion of the biological tissue during an exposure time; determining, for each exposure time in the set of exposure times, a third contrast value and a fourth contrast value, wherein determining a third contrast value for a given exposure time comprises determining an amount of variation between at least two intensities of light of the first polarization received from the further portion of biological tissue detected during at least two time periods associated with the given exposure time, and wherein determining a fourth contrast value for the given exposure time comprises determining an amount of variation between at least two intensities of light of the second polarization received from the further portion of biological tissue detected during at least two time periods associated with the given exposure time; determining a depth of a further region of flow within the biological tissue as a function of the determined third contrast values and the determined fourth contrast values; and using the determined depths of regions of flow within the biological tissue to generate a map of one or more portions of vasculature in the biological tissue. ### Claim 7 (depends on 1) The device of claim 1, wherein determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; determining a ratio between a determined first contrast value corresponding to the determined exposure time and a determined second contrast value corresponding to the determined exposure time; and using the determined ratio to determine the depth of the region of flow. ### Claim 8 (depends on 1) The device of claim 1, wherein determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; determining a difference between a determined first contrast value corresponding to the determined exposure time and a determined second contrast value corresponding to the determined exposure time; and using the determined difference to determine the depth of the region of flow. ### Claim 9 (depends on 1) The device of claim 1, wherein each time period being associated with a respective exposure time comprises the controller operating the at least one light sensor, during each time period, to detect light during an integration time having a duration corresponding to the exposure time of the time period. ### Claim 10 (depends on 1) The device of claim 1, wherein each time period being associated with a respective exposure time comprises the controller operating the light source, during each time period, to emit a pulse of light having a duration corresponding to the exposure time of the time period. ### Claim 11 A device comprising: a light source; at least one light sensor; and a controller, wherein the controller comprises a computing device programmed to perform operations comprising: during each of a plurality of time periods, wherein each time period is associated with a respective exposure time of a set of exposure times: emitting, by the light source, a beam of coherent illumination into a biological tissue; detecting, using the at least one light sensor, an intensity of light received from a first portion of the biological tissue during an exposure time; detecting, using the at least one light sensor, an intensity of light received from a second portion of the biological tissue during the exposure time; determining, for each exposure time in the set of exposure times, a first contrast value and a second contrast value, wherein determining a first contrast value for a given exposure time comprises determining an amount of variation between at least two intensities of light received from the first portion of biological tissue detected during at least two time periods associated with the given exposure time, and wherein determining a second contrast value for the given exposure time comprises determining an amount of variation between at least two intensities of light received from the second portion of biological tissue detected during at least two time periods associated with the given exposure time; and determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values. ### Claim 12 (depends on 11) The device of claim 11, further comprising: an endoscopic probe configured to be inserted into a body cavity, wherein the light source is configured to emit light from the endoscopic probe, and wherein the at least one light sensor is configured to detect light received from the biological tissue via the endoscopic probe. ### Claim 13 (depends on 11) The device of claim 11, wherein the operations further comprise: determining a flow velocity within the region of flow as a function of the determined first contrast values. ### Claim 14 (depends on 13) The device of claim 13, wherein the determined flow velocity is a flow velocity of blood cells in the region of flow. ### Claim 15 (depends on 13) The device of claim 13, wherein determining a flow velocity within the region of flow as a function of the determined first contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; and using the determined exposure time to determine a flow velocity within the region of flow. ### Claim 16 (depends on 11) The device of claim 11, wherein the operations further comprise: during each of the plurality of time periods: detecting, using the at least one light sensor, an intensity of light received from a third portion of the biological tissue during an exposure time; and detecting, using the at least one light sensor, an intensity of light received from a fourth portion of the biological tissue during an exposure time; determining, for each exposure time in the set of exposure times, a third contrast value and a fourth contrast value, wherein determining a third contrast value for a given exposure time comprises determining an amount of variation between at least two intensities of light received from the third portion of biological tissue detected during at least two time periods associated with the given exposure time, and wherein determining a fourth contrast value for the given exposure time comprises determining an amount of variation between at least two intensities of light of the second polarization received from the fourth portion of biological tissue detected during at least two time periods associated with the given exposure time; determining a depth of a further region of flow within the biological tissue as a function of the determined third contrast values and the determined fourth contrast values; and using the determined depths of regions of flow within the biological tissue to generate a map of one or more portions of vasculature in the biological tissue. ### Claim 17 (depends on 11) The device of claim 11, wherein determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; determining a ratio between a determined first contrast value corresponding to the determined exposure time and a determined second contrast value corresponding to the determined exposure time; and using the determined ratio to determine the depth of the region of flow. ### Claim 18 (depends on 11) The device of claim 11, wherein determining a depth of a region of flow within the biological tissue as a function of the determined first contrast values and the determined second contrast values comprises: detecting a feature in the determined first contrast values; determining an exposure time corresponding to the detected feature; determining a difference between a determined first contrast value corresponding to the determined exposure time and a determined second contrast value corresponding to the determined exposure time; and using the determined difference to determine the depth of the region of flow. ### Claim 19 (depends on 11) The device of claim 11, wherein each time period being associated with a respective exposure time comprises the controller operating the at least one light sensor, during each time period, to detect light during an integration time having a duration corresponding to the exposure time of the time period. ### Claim 20 (depends on 11) The device of claim 11, wherein each time period being associated with a respective exposure time comprises the controller operating the light source, during each time period, to emit a pulse of light having a duration corresponding to the exposure time of the time period.