# US 2024/0201496 A1 · Head mounted device with terahertz tracking > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2024/0201496 A1 - Document ID: US20240201496A1 - Status: Published application - Kind: A1 - Application number: 18/205,357 - Filed: 2023-06-02 - Published: 2024-06-20 - Earliest claimed: 2022-12-14 - Assignees: Meta Platforms Technologies, LLC - Applicants: Meta Platforms Technologies, LLC - Inventors: Gaetano Aiello - Web page: https://patentgrep.com/patent/US20240201496A1 ## CPC - G02B 27/0172: {characterised by optical features} - G01S 7/4812: {transmitted and received beams following a coaxial path} - G01S 7/4813: {Housing arrangements} - G01S 13/89: for mapping or imaging - G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) - G01S 17/66: Tracking systems using electromagnetic waves other than radio waves - G01S 17/87: Combinations of systems using electromagnetic waves other than radio waves - G01S 17/89: for mapping or imaging - G06F 3/013: {Eye tracking input arrangements (G06F3/015 takes precedence)} - G02B 2027/0138: {comprising image capture systems, e.g. camera} - G02B 2027/014: {comprising information/image processing systems} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - 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 - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Terahertz sensing in this disclosure involves the use of at least one terahertz signal that is transmitted towards an object. At least one return terahertz signal is reflected from the object. The return terahertz signal(s) may be analyzed to determine one or more parameters, such as phase, frequency, amplitude, spectral profile, time of flight (TOF) etc. associated with the return terahertz signal(s). Based on the parameter(s), a portion of the object impinged upon by the transmit terahertz signal(s) and which reflected the return terahertz signal(s), and the state of the object/portion, can be identified. The identification of the portion and its state can be used in eye tracking implementations. ## Claims ### Claim 1 A head mounted device, comprising: a terahertz sensor configured to: direct a transmit terahertz signal towards an eyebox region; and sense at least one return terahertz signal, wherein the at least one return terahertz signal is reflected from the eyebox region in response to the transmit terahertz signal; and processing logic coupled to the terahertz sensor and configured to identify, based on the at least one return terahertz signal sensed by the terahertz sensor, a portion of an object in the eyebox region. ### Claim 2 (depends on 1) The head mounted device of claim 1, wherein the portion of the object includes a portion of an eye or skin, and wherein identification of the portion includes determination of a state of the eye or object, including a gaze direction of the eye. ### Claim 3 (depends on 1) The head mounted device of claim 1, wherein to identify the portion of the object in the eyebox region based on the at least one return terahertz signal, the processing logic is configured to: determine a time of flight (TOF) based on a time between the transmit terahertz signal being directed towards the eyebox region and the at least one return terahertz signal being received by the terahertz sensor; and identify the portion of the object including a state of the portion of the object based at least in part on the TOF. ### Claim 4 (depends on 1) The head mounted device of claim 1, wherein to identify the portion of the object in the eyebox region based on the at least one return terahertz signal, the processing logic is configured to: perform spectral analysis on the at least one return terahertz signal to determine a spectral profile of the portion of the object; and identify the portion of the object including a state of the portion of the object based at least in part on the spectral profile. ### Claim 5 (depends on 1) The head mounted device of claim 1, wherein to identify the portion of the object in the eyebox region based on the at least one return terahertz signal, the processing logic is configured to: analyze the at least one return terahertz signal to associate the return terahertz signal with a particular signal in a machine learning (ML) dataset; and identify the portion of the object including a state of the portion of the object based at least in part on the associated particular signal. ### Claim 6 (depends on 1) The head mounted device of claim 1, wherein to identify the portion of the object in the eyebox region based on the at least one return terahertz signal, the processing logic is configured to: determine a parameter associated with the at least one return terahertz signal, wherein the parameter includes one or more of: a frequency, phase, amplitude, spectral profile, propagation path, time of flight (TOF), waveform shape, or beam width associated with the at least one return terahertz signal; and use the determined parameter to identify the portion of the object including a state of the portion of the object. ### Claim 7 (depends on 1) The head mounted device of claim 1, wherein: the transmit terahertz signal impinges on a particular region outside of the eyebox region, the at least one return terahertz signal includes a particular return terahertz signal reflected from the particular region, and the processing logic is further configured to identify the particular region based on the particular return terahertz signal. ### Claim 8 A method for a head mounted device to perform tracking using terahertz signals, the method comprising: directing a transmit terahertz signal towards an eyebox region; and sensing at least one return terahertz signal, wherein the at least one return terahertz signal is reflected from the eyebox region in response to the transmit terahertz signal; identifying, based on the at least one return terahertz signal, a portion of an object in the eyebox region; and performing an action pertaining to an operational feature of the head mounted device based on the identified portion of the object in the eyebox region. ### Claim 9 (depends on 8) The method of claim 8, wherein the portion of the object includes a portion of an eye or skin, and wherein identification of the portion includes determination of a state of the eye or object, including a gaze direction of the eye. ### Claim 10 (depends on 8) The method of claim 8, wherein identifying the portion of the object in the eyebox region based on the at least one return terahertz signal includes: determining a time of flight (TOF) based on a time between the transmit terahertz signal being directed towards the eyebox region and the at least one return terahertz signal being received by a terahertz sensor; and identifying the portion of the object including a state of the portion of the object based at least in part on the TOF. ### Claim 11 (depends on 8) The method of claim 8, wherein identifying the portion of the object in the eyebox region based on the at least one return terahertz signal includes: performing spectral analysis on the at least one return terahertz signal to determine a spectral profile of the portion of the object; and identifying the portion of the object including a state of the portion of the object based at least in part on the spectral profile. ### Claim 12 (depends on 8) The method of claim 8, wherein identifying the portion of the object in the eyebox region based on the at least one return terahertz signal includes: analyzing the at least one return terahertz signal to associate the return terahertz signal with a particular signal in a machine learning (ML) dataset; and identifying the portion of the object including a state of the portion of the object based at least in part on the associated particular signal. ### Claim 13 (depends on 8) The method of claim 8, wherein identifying the portion of the object in the eyebox region based on the at least one return terahertz signal includes: determining a parameter associated with the at least one return terahertz signal, wherein the parameter includes one or more of: a frequency, phase, amplitude, spectral profile, propagation path, time of flight (TOF), waveform shape, or beam width associated with the at least one return terahertz signal; and using the determined parameter to identify the portion of the object including a state of the portion of the object. ### Claim 14 (depends on 8) The method of claim 8, wherein: the transmit terahertz signal impinges on a particular region outside of the eyebox region, the at least one return terahertz signal includes a particular return terahertz signal reflected from the particular region, and the method further includes identifying the particular region based on the particular return terahertz signal. ### Claim 15 (depends on 8) The method of claim 8, wherein performing the action pertaining to the operational feature of the head mounted device includes making an adjustment to a display of the head mounted device that presents an image to the eyebox. ### Claim 16 A device, comprising: a terahertz transmitter configured to direct a transmit terahertz signal towards an object; a terahertz receiver configured to receive at least one return terahertz signal, wherein the at least one return terahertz signal is reflected from the object in response to the transmit terahertz signal; and a processing system coupled to the terahertz transmitter and to the terahertz receiver, and configured to identify, based on the at least one return terahertz signal sensed by the terahertz receiver, a portion of an object and a state of the portion of the object. ### Claim 17 (depends on 16) The device of claim 16, wherein to identify the portion of the object and the state of the portion of the object, the processing system is configured to: determine a time of flight (TOF) based on a time between the transmit terahertz signal being directed towards the object by the terahertz transmitter and the at least one return terahertz signal being received by the terahertz receiver; and identify the portion of the object and the state of the portion of the object based at least in part on the TOF. ### Claim 18 (depends on 16) The device of claim 16, wherein to identify the portion of the object and the state of the portion of the object, the processing system is configured to: perform spectral analysis on the at least one return terahertz signal to determine a spectral profile of the portion of the object; and identify the portion of the object and the state of the portion of the object based at least in part on the spectral profile. ### Claim 19 (depends on 16) The device of claim 16, wherein to identify the portion of the object and the state of the portion of the object, the processing system is configured to: analyze the at least one return terahertz signal to associate the return terahertz signal with a particular signal in a machine learning (ML) dataset; and identify the portion of the object and the state of the portion of the object based at least in part on the associated particular signal. ### Claim 20 (depends on 16) The device of claim 16, wherein the device is a head mounted device that uses the terahertz transmitter, the terahertz receiver, and the processing system for eye tracking.