分析了机载热红外扫描仪的信噪比与各种因素之间的关系，利用高斯－喇格尔公式给出了信噪比的解析表达式，阐述了提高信噪比的途径。分析了温度、发射率、扫描角度对系统信噪比的影响，得出了相应的理论公式，并定性分析了它们对信噪比的贡献。

Airborne thermal scanner is capable of obtaining terrestrial temperature distribution with high resolution and efficiency. One of the essential parameters is signal to noise ratio (SNR), which determines the final quality of thermal image. There are several factors such as emissivity, temperature, and scanning angle, which contribute to the SNR and in this paper, their influences on SNR have been theoretically analyzed and approaches of enhancing the SNR have been supplied. By using Gauss-Laguerre approximation method, the contributions of temperature, emissivity and scanning angle to the SNR have been studied and their mathematical expressions are presented. The theoretical estimation indicates that the emissivity has the highest influence on SNR and the scanning angle has the least one. The influence of scanning angle tends to lower the SNR and the value varies with angles. Laboratory measurement has been made, and the discrepancy between the theoretically computed and measured values of SNR is within the permissive error scope, considering the difference between conditions and that utilized to simulate.