A gas measurement system, comprising a coherent light source (1, 201, 301, 401), which emits a light beam; a detector (8, 208, 308, 408); a beam path (2, 202, 302), which is formed between the light source (1, 201, 301, 401) and the detector (8, 208, 308, 408); a gas cell (4, 204, 304, 404), which is arranged in the beam path between the light source (1, 201, 301, 401) and the detector (8, 208, 308, 408) such that the detector (8, 208, 308, 408) receives the light transmitted through the gas cell (4, 204, 304, 404); and an optical element (3, 203, 303, 403), which is arranged in the beam path (2, 202, 302) between the light source (1, 201, 301, 401) and the gas cell (4, 204, 304, 404); wherein the gas cell (4, 204, 304, 404) comprises a porous ceramic (11, 211, 311, 411); whereby entering light is reflected multiple times or randomly scattered within the ceramic before it then exits the ceramic, wherefore the gas cell (4, 204, 304, 404) has an optical path length which is a multiple of the actual layer thickness of the porous ceramic (11, 211, 311, 411) in the gas cell (4, 204, 304, 404) characterized in that the optical element (3, 203, 303, 403) i. is an optically transparent window, and widening of the light beam takes place based on the divergence of the light beam; or ii. comprises a diffuser or at least one diffractive optical element which deforms the light beam; such that the light beam emitted by the light source (1, 201, 301, 401) is widened and unfocused when entering the porous ceramic (11, 211, 311, 411) in the gas cell (4, 204, 304, 404); whereby the interferences that occur cancel each other out and can be filtered from the measuring signal. a coherent light source (1, 201, 301, 401), which emits a light beam; a detector (8, 208, 308, 408); a beam path (2, 202, 302), which is formed between the light source (1, 201, 301, 401) and the detector (8, 208, 308, 408); a gas cell (4, 204, 304, 404), which is arranged in the beam path between the light source (1, 201, 301, 401) and the detector (8, 208, 308, 408) such that the detector (8, 208, 308, 408) receives the light transmitted through the gas cell (4, 204, 304, 404); and an optical element (3, 203, 303, 403), which is arranged in the beam path (2, 202, 302) between the light source (1, 201, 301, 401) and the gas cell (4, 204, 304, 404); wherein the gas cell (4, 204, 304, 404) comprises a porous ceramic (11, 211, 311, 411); whereby entering light is reflected multiple times or randomly scattered within the ceramic before it then exits the ceramic, wherefore the gas cell (4, 204, 304, 404) has an optical path length which is a multiple of the actual layer thickness of the porous ceramic (11, 211, 311, 411) in the gas cell (4, 204, 304, 404) characterized in that the optical element (3, 203, 303, 403) i. is an optically transparent window, and widening of the light beam takes place based on the divergence of the light beam; or ii. comprises a diffuser or at least one diffractive optical element which deforms the light beam; i. is an optically transparent window, and widening of the light beam takes place based on the divergence of the light beam; or ii. comprises a diffuser or at least one diffractive optical element which deforms the light beam; such that the light beam emitted by the light source (1, 201, 301, 401) is widened and unfocused when entering the porous ceramic (11, 211, 311, 411) in the gas cell (4, 204, 304, 404); whereby the interferences that occur cancel each other out and can be filtered from the measuring signal.