Gas analyzer and gas analysis method

A gas analyzer comprising:

• a detector;
• a Herriott cell containing a measurement gas with two mirrors;
• and
• at least two different radiation sources arranged and aligned in relation to the Herriott cell such that beams which are coupled by said at least two different radiation sources into the Herriott cell and reflected between the two mirrors strike the two mirrors in point patterns which extend along ellipses;
• wherein the ellipses lie inside one another and have two shared vertices or co-vertices on a shared axis of symmetry and other co-vertices or vertices which do not coincide;
• wherein the beams of at least two of the least two different radiation sources at least one of (i) enter the Herriott cell at differing points of the associated point pattern and (ii) enter the Herriott cell such that said beams of at least two of the at least two different radiation sources pass through the associated point patterns along the ellipses in opposite directions;
• wherein all beams exit the Herriott cell at a point of one of the shared vertices and strike the detector;
• and
• wherein said beams of the at least two of the different radiation sources pass through differing path lengths in the Herriott cell.