一种用于确定燃气 - 空气混合物（2）的空气比的传感器，其中形成有限制测量空间（4）的壳体（3）。 壳体（3）在一侧上具有用于与燃料气体 - 空气混合物流（2）联接的扩散通道，其中扩散通道由透气分离装置（5）形成。 电动激励装置（8）被布置用于将能量供应到测量空间（4）中，以便引起测量空间中的燃料气体 - 空气混合物的化学反应。 激励装置（8）被设计和对准以影响位于测量空间中的反应位置处的能量供应。 该反应位置位于与壳体（3）或分离装置（5）的清除距离内。 至少一个光学检测装置（13，14）与所述测量室的感测区域（4）定向，所述光学检测装置（13，14）检测到的辐射的强度从反应位置中的至少一个第一波长范围和相关联的检测到的强度信号 （15）产生空气比可导出。

A sensor for determining an air ratio of a fuel gas-air mixture (2), a housing (3) is formed, which delimits a measuring chamber (4). The housing (3) has on one side a diffusion passage for coupling to a fuel gas-air mixture stream (2), wherein the diffusion passage is formed by a gas-permeable separating means (5). An electrically powered excitation means (8) is arranged for supplying energy to the measuring chamber (4) to bring about a chemical reaction of a fuel gas-air mixture in the measuring space. The excitation means (8) is designed and oriented to cause the power supply at a location in the measuring room reaction position. This reaction position is located within an erase distance to the housing (3) or the separating means (5).
At least one optical detection device (13, 14) with its sensing area in the measuring chamber (4) directed, said optical detecting means (13, 14) detects the intensity of radiation from the reaction position in at least a first wavelength range and the detected intensity signal associated (15) is generated, from which the air ratio can be derived.