US 12,135,365 B2
Method and device for interferometric range measurements
Kirk W. Madison, Vancouver (CA); and Kyzyl Herzog, Vancouver (CA)
Assigned to Illusense, Inc., Vancouver (CA)
Filed by Illusense, Inc., Vancouver (CA)
Filed on Jun. 9, 2022, as Appl. No. 17/836,241.
Application 17/836,241 is a division of application No. 16/288,951, filed on Feb. 28, 2019, granted, now 11,391,834.
Claims priority of provisional application 62/721,344, filed on Aug. 22, 2018.
Claims priority of provisional application 62/636,422, filed on Feb. 28, 2018.
Prior Publication US 2022/0334242 A1, Oct. 20, 2022
Int. Cl. G01S 13/86 (2006.01); G01S 7/285 (2006.01); G01S 7/4912 (2020.01); G01S 13/10 (2006.01); G01S 17/10 (2020.01); G01S 17/32 (2020.01); G01S 13/28 (2006.01)
CPC G01S 13/865 (2013.01) [G01S 7/285 (2013.01); G01S 7/4917 (2013.01); G01S 13/10 (2013.01); G01S 17/10 (2013.01); G01S 17/32 (2013.01); G01S 13/288 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An apparatus for determining a range of one or more targets, the apparatus comprising:
an electromagnetic radio frequency (RF) field source, the field source configured to generate an RF source field;
an optical field source, configured to generate an optical source field;
an optical field modulator;
an optical field demodulator; and
wherein:
the apparatus is configured to receive the RF source field and divide the RF source field into an RF probe field, having an RF probe phase, and an RF reference field, having an RF reference phase,
the apparatus further including:
a probe phase modulator, configured to modulate the RF probe phase, and
a reference phase modulator, configured to modulate the RF reference phase;
the optical field modulator configured to receive the RF probe field and the optical source field and to amplitude-modulate the optical source field according to the RF probe field, thereby generating an optical probe field;
the apparatus is further configured to direct the optical probe field to the one or more targets, to receive a reflected optical probe field from the one or more targets, and to direct the reflected optical field to the optical field demodulator;
the optical field demodulator configured to receive the reflected optical field and demodulate the reflected optical field into a reflected RF probe field;
the apparatus is further configured to direct the reflected RF probe field and the RF reference field to the detector;
the detector configured to detect the reflected RF probe field and the RF reference field and to generate a detector signal corresponding to a product of the reflected RF probe field and the RF reference field, the detector signal having a DC component and an AC component;
a power meter, configured to measure the AC component; and
a computing node, in communication with the probe phase modulator, the reference phase modulator, and the power meter, the computing node configured to:
cause the probe phase modulator to modulate the RF probe phase according to a probe time-periodic waveform having a probe modulation phase that includes a probe modulation frequency and a probe modulation phase offset;
cause the reference phase modulator to modulate the RF reference phase according to a reference time-periodic waveform having a reference modulation phase that includes a reference modulation frequency and a reference modulation phase offset;
generate a representation of the power of the AC component corresponding to the one or more time-periodic waveforms;
determine a difference between the probe modulation phase and the reference modulation phase corresponding to the extrema of the representation of the power of the AC component; and
determine the range to the one or more targets based on the extrema of the power of the AC component.