Patent ID: 11940386
Assignee: THE UNIVERSITY OF BRITISH COLUMBIA
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 15:
16. Apparatus for monitoring a sample for at least one analyte, the apparatus comprising:
an optical waveguide comprising a sensing portion and a phase shift portion wherein the sensing portion passes through a volume for receiving the sample;
a fixed wavelength light source coupled to deliver fixed wavelength light into the waveguide;
a phase shift modulator operative to periodically modulate a phase shift of the light effected by the phase shift portion of the optical waveguide;
at least one light detector operable to monitor an intensity of the light relative to the phase shift of the light effected by the phase shift portion of the waveguide; and
a lock-in detection system, the lock in detection system comprising electronics configured to generate a lock-in signal Vch2(t) from a phase shift modulation control signal Vch1(t), the lock-in signal having a fixed phase relationship to the phase shift modulation control signal; a mixing circuit configure to mix the lock-in signal with an output of the light detector; and an integration circuit configured to integrate an output of the mixing circuit over a plurality of cycles of the phase shift modulation control signal.