为了深入理解激光清洗技术清除石质文物表面污染物作用机制，进行了激光清洗砂岩表面墨迹和烟熏污染物实验，得到其清洗阈值，结合理论计算得到此时污染物表面的温度场和应力场的情况，对激光清除机制进行了分析，认为温升引起汽化蒸发以及热应力是其污染物被清除的主要方式。在此基础上，在山西大同云冈石窟进行现场实验，结果表明激光能安全有效去除墨迹和烟熏污染物。

For better understanding the mechanisms of laser cleaning for contamination on surface of stonework, such as black ink and smoked dirt, the cleaning experiments are carried out. Its cleaning thresholds are obtained. Meanwhile, the finite element analysis software is used to calculate the temperature and stress of contamination under laser irradiation. The experimental results are discussed combining the calculation. The evaporation of contamination and thermal stress could be the main causes for removing of the pollutants. The site experiment of laser cleaning of black ink and smoked dirt in Yungang grottoes shows that this technique has a great advantage and can be applied for conservation of stonework.