Compact multi-pass absorption gas cell

A gas detection system comprising:

• a compact multi-pass absorption gas cell comprising:
• a rectangular housing defining a chamber for receiving a sample to be analyzed;
• a light inlet positioned at a first end of the rectangular housing for introducing light beam into the chamber;
• a light outlet position at a second end of the rectangular housing;
• a first mirror component positioned at the first end, the first mirror component comprising a first flat mirror and a first concave mirror array;
• and
• a second mirror component positioned at the second end, the second mirror component comprising a second flat mirror and a second concave mirror array, wherein the light beam reflects multiple times between the first mirror component and the second mirror component and is refocused by the first concave mirror array and the second concave mirror array to achieve an optical path length for low absorption gas detection;
• a light emitter configured to emit light beam toward the compact multi-pass absorption gas cell;
• and
• a light receiver configured to receive light exiting the compact multi-pass absorption gas cell.