US 12,474,206 B2
Fibre optic filter remote gas correlation sensor
Ross Cheriton, Ottawa (CA); Siegfried Janz, Ottawa (CA); and Adam Densmore, Victoria (CA)
Assigned to NATIONAL RESEARCH COUNCIL OF CANADA, Ottawa (CA)
Appl. No. 17/926,047
Filed by National Research Council of Canada, Ottawa (CA)
PCT Filed May 19, 2021, PCT No. PCT/CA2021/050678
§ 371(c)(1), (2) Date Nov. 17, 2022,
PCT Pub. No. WO2021/232153, PCT Pub. Date Nov. 25, 2021.
Claims priority of provisional application 63/122,255, filed on Dec. 7, 2020.
Prior Publication US 2023/0184587 A1, Jun. 15, 2023
Int. Cl. G01J 3/02 (2006.01); G01J 3/26 (2006.01); G01J 3/433 (2006.01); G01N 21/359 (2014.01)
CPC G01J 3/0218 (2013.01) [G01J 3/0297 (2013.01); G01J 3/26 (2013.01); G01J 3/433 (2013.01); G01N 21/359 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method for detecting and identifying a remote gas, the method comprising the steps of:
receiving a light wave associated with the remote gas;
coupling the light wave into a single mode fibre;
transmitting the light wave via the single mode fibre into a filter comprising a fibre-based tunable cavity;
modulating the cavity length of the filter transmission window to cause a detected modulated signal that is proportional to the spectral feature; and
processing the signal using a lock-in amplifier capable of low-pass filtering and out-of-frequency noise rejection, wherein an output from the lock-in amplifier is a function of a phase shift due to a radial velocity of the remote gas.