Intrinsically safe NDIR gas sensor in a can

A Non-Dispersive Infrared (“NDIR”) gas sensor for detecting the presence of a chosen gas, comprising:

• a Central Processing Unit (“CPU”);
• a first and a second Integrated Detector Filter ASIC module (“IDFA”), each of which is comprised of a thermopile detector with an identical narrow bandpass filter mounted on top and communicable with an Application Specific Integrated Circuit (“ASIC”) such that infrared radiation received by the thermopile detector after passing through the identical narrow bandpass filter is converted into a digital signal ready to be transmitted to the CPU;
• a mechanical housing comprising:
• a can having a plurality of inner reflective surfaces;
• and
• a header housing affixed to the can having a top surface with a pair of windows formed in the top surface and containing a tunnel waveguide sample chamber in its body;
• and
• a Microelectronic Mechanical System (“MEMS”) source mounted to the top surface that emits radiation when power is applied to it;
• wherein the first and the second IDFA are affixed to the top surface so that the plurality of inner reflective surfaces and the tunnel waveguide sample chamber create a signal channel path length detected by the first IDFA that is sufficiently greater than a reference channel path length detected by the second IDFA so that the CPU can use an absorption bias between a signal output of the first IDFA and a reference output of the second IDFA to determine the chosen gas concentration in the sample chamber.