US 12,228,502 B2
Gas detection using differential path length measurement
Shrenik Deliwala, Andover, MA (US)
Assigned to ANALOG DEVICES, INC., Wilmington, MA (US)
Filed by Analog Devices, Inc., Wilmington, MA (US)
Filed on Dec. 15, 2022, as Appl. No. 18/066,766.
Application 18/066,766 is a division of application No. 16/872,758, filed on May 12, 2020, granted, now 11,747,272.
Claims priority of provisional application 62/859,276, filed on Jun. 10, 2019.
Prior Publication US 2023/0120444 A1, Apr. 20, 2023
Int. Cl. G01N 21/3504 (2014.01); G01N 33/00 (2006.01)
CPC G01N 21/3504 (2013.01) [G01N 33/004 (2013.01); G01N 2201/062 (2013.01); G01N 2201/0668 (2013.01); G01N 2201/0686 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical differential path length gas detector comprising:
a light source producing a first light;
a light filter disposed proximally to the light source;
a first conic-section optic configured to split the light into two pathways, a second and third light, respectively, after having passed through the light filter;
a first photodetector configured to measure the second light, wherein the first photodetector is configured to have a shorter pathlength than the third light; and
a second conic-section optic configured to direct the third light to a second photodetector;
wherein the second photodetector is configured to measure the third light.