目标红外测距的实现同气体及其波段的选取密切相关。氧气A吸收带具有独特的谱线结构，对于火箭羽流或者高温辐射体的距离探测，氧气A吸收带是最佳的距离反演通道。通过深入研究逐线积分算法，设计了氧气A带标准光谱计算软件；利用吸收带带外数据，采用基线拟合的方法反演不同距离的带平均透射率，进而得到相应的距离。将ABB灯作为被测光源，在不同的距离下采集相应的光谱，并进行拟合计算，将实测数据的拟合计算结果同理论计算结果进行对比验证，其误差低于0.5%,在允许范围内。

Realization of passive ranging based on infrared radiation and atmospheric attenuation characteristics is closely related to gas band selection. Oxygen A absorption band has a unique spectral structure. For rocket plume and high temperature radiation, the band is the best inversion channel of distance. Through the in-depth research of line-by-line radiative transfer model (LBLTRM), Oxygen A band standard spectrum calculation software is designed. Making use of the out-of-band data, band average transmittance in different distances is obtained by polynomial fitting, and then the corresponding distance is received. Putting the ABB lamp as the light source, collecting the corresponding spectrum in different distances and making the fitting calculation, through the comparison of fitting results of the measured datas and theoretical calculation results, the error is within 0.5% and is in the permissible range.