Active illumination and time-of-flight camera system to evaluate facial blood flow, eye movements and physiological parameters
A measurement system comprising one or more semiconductor diodes configured to penetrate tissue comprising skin. The detection system comprising a camera, which may also include a direct or indirect time-of-flight sensor. The detection system synchronized to the pulsing of the semiconductor diodes, and the camera further coupled to a processor. The detection system non-invasively measuring blood within the skin, measuring hemoglobin absorption between 700 to 1300 nm, and the processor deriving physiological parameters and comparing properties between different spatial locations and variation over time. The semiconductor diodes may comprise vertical cavity surface emitting lasers, and the detection system may comprise single photon avalanche photodiodes. The measurement system may be used to observe eye parameters and differential blood flow. The system may be used with photo-bio-modulation therapy, or it may be used in advanced driver monitoring systems for multiple functions including head pose, eye tracking, facial authentication, and smart restraint control systems.
1. A measurement system comprising:
one or more semiconductor diodes to operate in a pulsed mode and to generate a pulsed light having one or more optical wavelengths that includes at least one near-infrared wavelength, wherein at least a portion of the pulsed light generated by the one or more semiconductor diodes is configured to penetrate tissue comprising skin;
a detection system comprising a camera, wherein the detection system is configured to be synchronized to the pulsed light of the one or more semiconductor diodes, and wherein the detection system further comprises one or more lenses in front of at least a part of the detection system;
the camera configured to receive at least a portion of the pulsed light reflected from the tissue from at least a part of the one or more semiconductor diodes, wherein the camera is configured to generate data based at least in part on the portion of the pulsed light received, and the camera is further coupled to a processor;
wherein the measurement system including the processor is configured to generate an image using at least part of the data from the detection system;
the detection system configured to non-invasively measure blood in blood vessels within or below a dermis layer within the skin based at least in part on reflection from the skin;
the detection system configured to measure absorption of hemoglobin in the near-infrared wavelength between 700 nanometers and 1300 nanometers;
wherein the processor is configured to compare the absorption of hemoglobin between different spatial locations of tissue;
wherein the measurement system including the processor is configured to measure one or more physiological parameters based at least in part on the non-invasively measured blood within the tissue, and wherein the measurement system including the processor is configured to measure over a period of time a variation in the blood within the tissue or the one or more physiological parameters; and
wherein the measurement system including the processor is further configured to be coupled to an active remote sensing system comprising:
one or more laser diodes configured to generate laser light having an initial light intensity and one or more second optical wavelengths, wherein at least a portion of the one or more second optical wavelengths is between 700 nanometers and 2500 nanometers, wherein the one or more laser diodes comprises one or more Bragg reflectors, wherein the one or more laser diodes is further configured to be modulated with a pulsed output with a pulse duration of approximately 0.5 to 2 nanoseconds and a pulse repetition rate between about 10 Megahertz and 1 Gigahertz, wherein the one or more laser diodes is further configured to be coupled to driver electronics, and wherein the laser light from the one or more laser diodes is configured to be directed to the tissue; and
a second detection system comprising a photodiode array, wherein the second detection system further comprises one or more second lenses and one or more spectral filters in front of at least a part of the photodiode array, wherein the photodiode array is further coupled to the processor, and wherein the photodiode array comprises a plurality of pixels coupled to CMOS transistors;
wherein the second detection system is configured to receive at least a portion of laser light from the one or more laser diodes reflected from the tissue, and wherein the second detection system is further configured to be synchronized to the one or more laser diodes comprising Bragg reflectors;
wherein the second detection system is further configured to perform a time-of-flight measurement based on a time difference between a first time in which the one or more laser diodes generate laser light and a second time in which the photodiode array receives the at least a portion of laser light from the one or more laser diodes reflected from the tissue; and
wherein the second detection system is further configured to perform the time-of-flight measurement at least in part by measuring a temporal distribution of photons in the received portion of laser light from the one or more laser diodes reflected from the tissue.
2. The measurement system of claim 1 , wherein the one or more laser diodes comprises vertical cavity surface emitting lasers, wherein the photodiode array comprises single-photon avalanche photodiodes, and wherein at least some of the one or more second optical wavelengths are near 850 nanometers or near 940 nanometers.
3. The measurement system of claim 2 , wherein the processor analyzes information from one or both of the detection system or the second detection system using artificial intelligence, machine learning, deep learning, or generative artificial intelligence.
4. The measurement system of claim 3 , wherein depth information from the time-of-flight measurement is used at least in part to compensate for motion artifacts.
5. The measurement system of claim 4 , wherein the measurement system including the processor is configured to compare differential blood flow between a forehead region and a nose region or between the forehead region and a cheek region on a user; or
wherein the measurement system including the processor is further coupled to a therapy or diagnostic system comprising additional light sources configured to emit additional light between approximately 700 and 1100 nanometers, wherein the additional light from the additional light sources is configured to be directed toward the forehead region on the user, and wherein the additional light sources comprise vertical cavity surface emitting lasers or light emitting diodes.
6. The measurement system of claim 4 , wherein the measurement system including the processor is configured to be used in an advance driver assistance system or a driver monitoring system and configured to perform functions selected from the group consisting of (i) head pose, (ii) eye parameters, (iii) facial authentication, (iv) vital sign monitoring, (v) facial blood flow for drowsiness or impaired or drunk driver detection, and (vi) smart restraint control systems.
7. The measurement system of claim 3 , wherein the camera is configured to measure near an eye region of a user, and wherein the processor is configured to determine eye parameters selected from the group consisting of eye blink rate, percent of eye closure, pupil dilation, eye gaze direction, eye saccade and eye fixation.