# US 2024/0201343 A1 · Lidar system with supressed doppler frequency shift > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2024/0201343 A1 - Document ID: US20240201343A1 - Status: Published application - Kind: A1 - Application number: 18/556,030 - Filed: 2021-04-21 - Published: 2024-06-20 - Earliest claimed: 2021-04-21 - Assignees: Ommatidia LIDAR S.L. - Applicants: Ommatidia LIDAR S.L. - Inventors: Eduardo Margallo Balbás; José Luis Rubio Guivernau - Web page: https://patentgrep.com/patent/US20240201343A1 ## CPC - G01S 7/4912: Receivers - G01S 7/4913: Circuits for detection, sampling, integration or read-out - G01S 7/4917: {superposing optical signals in a photodetector, e.g. optical heterodyne detection} - G01S 7/493: Extracting wanted echo signals - G01S 17/34: using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal - G01S 17/50: Systems of measurement based on relative movement of target - G01S 17/89: for mapping or imaging - 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 A LIDAR system which reduces or suppress the frequency shift induced by the movement of objects in a scene relative to the LIDAR, and which comprises a light source, an input aperture (101), a splitter (2) configured to split a reflected light into a reference channel (4) and a first imaging channel (3), a first imaging optical IQ receiver (5) configured to obtain a first interference signal, a reference optical IQ receiver (6) configured to obtain a reference interference signal, an imaging oscillator (111), configured to be temporarily coherent with the reflected light, at least a mixer (12), connected to the first imaging optical IQ (5) and to the reference optical IQ (6) and configured to obtain a first intermodulation product with a higher frequency and an intermodulation product of interest with its Doppler Shift scaled. ## Claims ### Claim at position 1 1-29. (canceled) ### Claim 30 A light detection and ranging (LIDAR) system with suppressed Doppler frequency shift, wherein the system comprises: at least one light source configured to emit a first light; at least one imaging input aperture and one imaging channel associated to the at least one imaging input aperture, configured to receive an input reflected light that is reflected by a moving object that is irradiated by the light source; at least one reference aperture and one reference channel associated to the at least one reference aperture, configured to receive a reference reflected light that is reflected by the moving object that is irradiated by the light source; at least one imaging oscillator; at least one first imaging optical receiver associated to the imaging input aperture and the imaging oscillator and configured to obtain an interference signal between the input reflected light and the imaging oscillator; a reference oscillator; a reference optical receiver associated to the reference aperture and the reference oscillator and configured to obtain a reference interference signal between the reference reflected light and the reference oscillator; a signal filter arrangement positioned following the reference optical receiver, wherein the signal filter arrangement comprises a temporal filtering unit configured to accumulate samples of the reference interference signal and combine the samples to increase the SNR of the reference interference signal; and at least one mixer, connected to the at least a first imaging optical receiver and to the signal filter arrangement and configured to produce an intermodulation product between the interference signal and the reference interference signal, such that the Doppler frequency shift caused by the moving object is cancelled or decreased. ### Claim 31 (depends on 30) The LIDAR system of claim 30, wherein the at least a first imaging optical receiver is an optical IQ receiver configured to obtain an interference signal between the input reflected light and the imaging oscillator comprising a first in phase component and a first quadrature component, and the reference optical receiver is an optical IQ receiver configured to obtain a reference interference signal comprising a reference in-phase component and a reference quadrature component. ### Claim 32 (depends on 31) The LIDAR system of claim 31, further comprising a time derivation module, associated to the reference optical receiver and intended to time derivate the reference in-phase component and the reference quadrature component. ### Claim 33 (depends on 31) The LIDAR system of claim 31, wherein the at least one mixer comprises: a first mixer, intended to mix the first quadrature component and the reference in-phase component; and a second mixer, intended to mix the first in-phase component and the reference in-phase component. ### Claim 34 (depends on 33) The LIDAR system of claim 33, further comprising a low-pass filter associated with each mixer. ### Claim 35 (depends on 31) The LIDAR system of claim 31, wherein the at least one mixer comprises: a first mixer, intended to mix the first quadrature component and the reference quadrature component; and a second mixer, intended to mix the first in-phase component and the reference quadrature component. ### Claim 36 (depends on 31) The LIDAR system of claim 31, wherein the at least one mixer comprises: a third mixer, intended to mix the first in-phase component and the time-derived reference quadrature component; and a fourth mixer, intended to mix the first quadrature component and the time-derived reference quadrature component. ### Claim 37 (depends on 31) The LIDAR system of claim 31, wherein the at least one mixer comprises: a third mixer, intended to mix the first in-phase component and the time-derived reference in-phase component; and a fourth mixer, intended to mix the first quadrature component and the time-derived reference in-phase component. ### Claim 38 (depends on 31) The LIDAR system of claim 31, further comprising transimpedance amplifiers positioned following the reference optical receiver and the first imaging optical receiver, and configured to amplify the reference in-phase component, the reference quadrature component, the first in-phase component and the first quadrature component. ### Claim 39 (depends on 30) The LIDAR system of claim 30, wherein the reference oscillator and the imaging oscillator share a common origin. ### Claim 40 (depends on 30) The LIDAR system of claim 30, wherein the reference aperture is the same as the input aperture and the reference channel and the imaging channel are derived from it by means of a splitter. ### Claim 41 (depends on 30) The LIDAR system of claim 30, wherein the reference oscillator's wavelength stays static and the first optical oscillator's wavelength is swept following a standard FMCW (Frequency Modulated Continuous Wave) scheme. ### Claim 42 (depends on 30) The LIDAR system of claim 30, further comprising one or more low-pass filters, associated with the optical receivers and configured to filter the interference signal and the reference interference signal. ### Claim 43 (depends on 30) The LIDAR system of claim 30, wherein the mixers are Gilbert cells. ### Claim 44 (depends on 30) The LIDAR system of claim 30, wherein the signal filter arrangement mixes the reference interference signal with a plurality of other reference signals. ### Claim 45 (depends on 30) The LIDAR system of claim 30, wherein the temporal filtering unit is configured to combine the samples by averaging the samples. ### Claim 46 (depends on 30) The LIDAR system of claim 30, wherein the temporal filtering unit is configured to combine the samples by using a series of phase locked loops (PLLs). ### Claim 47 A LIDAR system that comprises: at least one light source configured to emit a first light; at least one imaging input aperture and one imaging channel associated to the at least one imaging input aperture, configured to receive an input reflected light that is reflected by a moving object that is irradiated by the light source; at least one reference aperture and one reference channel associated to the at least one reference aperture, configured to receive a reference reflected light that is reflected by the moving object that is irradiated by the light source; at least one imaging oscillator; at least one first imaging optical receiver associated to the imaging input aperture and the imaging oscillator and configured to obtain an interference signal between the input reflected light and the imaging oscillator; a reference oscillator; a reference optical receiver associated to the reference aperture and the reference oscillator and configured to obtain a reference interference signal between the reference reflected light and the reference oscillator; a signal filter arrangement positioned following the reference optical receiver, wherein the signal filter arrangement comprises a temporal filtering unit configured to accumulate samples of the reference interference signal and combine the samples to increase the SNR of the reference interference signal; and an optical modulator connected to the at least one imaging oscillator, and configured to apply an amplitude or phase modulation to the at least one imaging oscillator based on a signal derived from the reference channel, such that an intermodulation product between the interference signal and the reference interference signal appears at the output of the at least a first imaging optical receiver, such that the Doppler frequency shift caused by the moving object is cancelled or decreased. ### Claim 48 (depends on 47) The LIDAR system of claim 47, wherein the at least a first imaging optical receiver is an optical IQ receiver configured to obtain an interference signal between the input reflected light and the imaging oscillator comprising a first in phase component and a first quadrature component, and the reference optical receiver is an optical IQ receiver configured to obtain a reference interference signal comprising a reference in-phase component and a reference quadrature component. ### Claim 49 (depends on 48) The LIDAR system of claim 48, further comprising transimpedance amplifiers positioned following the reference optical receiver and the first imaging optical receiver, and configured to amplify the reference in-phase component, the reference quadrature component, the first in-phase component and the first quadrature component. ### Claim 50 (depends on 47) The LIDAR system of claim 47, wherein the reference oscillator and the imaging oscillator share a common origin. ### Claim 51 (depends on 47) The LIDAR system of claim 47, wherein the reference aperture is the same as the input aperture and the reference channel and the imaging channel are derived from it by means of a splitter. ### Claim 52 (depends on 47) The LIDAR system of claim 47, wherein the reference oscillator's wavelength stays static and the first optical oscillator's wavelength is swept following a standard FMCW (Frequency Modulated Continuous Wave) scheme. ### Claim 53 (depends on 47) The LIDAR system of claim 47, further comprising one or more low-pass filters, associated to the optical receivers and configured to filter the interference signal and the reference interference signal. ### Claim 54 (depends on 47) The LIDAR system of claim 47, wherein the signal filter arrangement mixes the reference interference signal with a plurality of other reference signals. ### Claim 55 (depends on 47) The LIDAR system of claim 47, wherein the temporal filtering unit is configured to combine the samples by averaging the samples. ### Claim 56 (depends on 47) The LIDAR system of claim 47, wherein the temporal filtering unit is configured to combine the samples by using a series of phase locked loops (PLLs). ### Claim 57 A LIDAR system that comprises: at least one light source configured to emit a first light; at least one imaging input aperture and one imaging channel associated to the at least one imaging input aperture, configured to receive an input reflected light that is reflected by a moving object that is irradiated by the light source; at least one reference aperture and one reference channel associated to the at least one reference aperture, configured to receive a reference reflected light that is reflected by the moving object that is irradiated by the light source; at least one imaging oscillator; at least one first imaging optical receiver associated to the imaging input aperture and the imaging oscillator and configured to obtain an interference signal between the input reflected light and the imaging oscillator; a reference oscillator; a reference optical receiver associated to the reference aperture and the reference oscillator and configured to obtain a reference interference signal between the reference reflected light and the reference oscillator; a signal filter arrangement positioned following the reference optical receiver, wherein the signal filter arrangement comprises a temporal filtering unit configured to accumulate samples of the reference interference signal and combine the samples to increase the SNR of the reference interference signal; and wherein the at least one light source comprises a source modulation scheme configured to apply an amplitude or phase modulation to the emitted first light based on a signal derived from the reference channel, such that an intermodulation product between the interference signal and the reference interference signal appears at the output of the at least a first imaging optical receiver, such that the Doppler frequency shift caused by the moving object is cancelled or decreased. ### Claim 58 (depends on 57) A method for suppressing Doppler frequency shift in the LIDAR system of claim 57, the method comprising: emitting a first light, aimed at a moving object; receiving a reflected light coming from the moving object; obtaining a first interference signal between the reflected light and an imaging oscillator; obtaining a reference interference signal between the reflected light and a reference oscillator; accumulating samples of the reference interference signal and averaging the samples to increase the SNR of the reference interference signal; and obtaining an intermodulation product between the interference signal and the reference interference signal, such that the Doppler frequency shift caused by the moving object is cancelled or decreased.