| CPC G01N 21/39 (2013.01) [G01N 2021/394 (2013.01); G01N 2021/399 (2013.01)] | 14 Claims |

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1. A system for open path gas detection, the system comprising:
a laser having a wavelength centered on two or more absorption features in a spectrum of a gas and a linewidth overlapping with the two or more absorption features in the spectrum of the gas and an adjacent region of lower absorption in the spectrum of the gas;
at least one sensor to determine a received power of the laser including a first portion corresponding to overlap with the two or more absorption features and a second portion corresponding to overlap with the adjacent region of lower absorption;
a computing device that executes instructions to detect the gas based on the received power of the laser, wherein the computing device executes instructions to quantify an amount of the gas between the laser and a target based on a difference between the first portion of the received power of the laser and the second portion of the received power of the laser; and
one or more of a grating, prism, or filter configured to split the received power into the first portion of the received power of the laser and the second portion of the received power of the laser.
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