在设计三通道非成像氧气吸收被动测距系统过程中，确定各通道光电倍增管的绝对光谱响应率对确保系统测距精度具有重要意义。为了克服光电倍增管灵敏度高、易饱和而导致的单色光功率测量困难的问题，提出了一种光电倍增管绝对光谱响应率测量方法。在该方法中，利用积分球与可调狭缝构建通量可调的系统光源，利用响应率已知的标准探测器测量单色光源辐射功率。搭建了光电倍增管绝对光谱灵敏度测量系统，并对三根滨松H10722-01型光电倍增管模块进行绝对光谱响应率测量。同时，为了检验该测量方法的有效性，在外场条件下开展了近程被动测距实验，将测量得到的光电倍增管绝对光谱响应率作为三通道被动测距系统各通道的光谱响应率参数。实验结果表明：在60～300 m范围内，测距平均相对误差为6.25%。实验结果证明了该绝对光谱响应率测量方法的有效性。

In designing a three-channel non-imaging passive ranging system based on oxygen absorption, determining the absolute spectral sensitivity of the photomultiplier tubes is of great significance to ensure the ranging accuracy of the system. In order to overcome the difficulty of monochromatic light power measurement caused by high sensitivity and saturation of photomultiplier tube, we propose a measurement method of absolute spectral sensitivity of photomultiplier tubes. In this method, a system light source with adjustable flux is constructed using an integrating sphere and an adjustable slit, and a standard detector with known spectral sensitivity is used to measure the radiant power of the monochromatic light source. An absolute spectral sensitivity measurement system for photomultiplier tube is established, and the absolute spectral sensitivity of three H10722-01 photomultiplier tubes is measured with this method. In order to test the effectiveness of the proposed measurement method, a short-range passive ranging experiment is conducted in external field, the measured absolute spectral sensitivity of the photomultiplier tubes is used as the spectral sensitivity parameter of the passive ranging system. The experimental results show that in the range of 60-300 m, the average relative error of distance measurement is 6.25%. The experimental results prove the validity of this absolute spectral sensitivity measurement method.