Patent ID: 11874110
Assignee: APPLE INC.
Field: Measurement (Instruments)
Classification: CPC G  A | IPC G

Claim 0:
1. An apparatus for performing non-reciprocal self-mixing interferometry, the apparatus comprising:
a self-mixing interferometry sensor having a light source configured to emit a beam of light; and
a birefringent circulator positioned over an aperture of the light source and configured to direct the beam of light emitted by the light source along an illumination path, the birefringent circulator comprising:
a Faraday rotator; and
a wave plate, wherein the Faraday rotator and the wave plate are configured to transform a first polarization of the beam of light into a second polarization as the beam of light travels along the illumination path, wherein:

the birefringent circulator directs a returned portion of the beam of light, received along a collection path different from the illumination path, back toward the light source.