针对光通信终端的光学表面污染, 研制了10 MHz镀铝石英晶体微天平(QCM), 用于实时检测真空试验中的污染量以保证光通信的可靠性。该装置通过引入参考晶体消除环境因素的影响, 并降低对其控温精度的要求, 其理论质量灵敏度可达10-9g/cm2。经过绝对标定实验后, 其实际质量灵敏度为10-8g/cm2, 满足应用需求, 且成本低, 实用性好, 可用于星上或地面污染检测。文中依据不同的污染源工作温度, 分别在32 ℃高温恒温段, 32 ℃~-27 ℃降温段, 低温保持段及-2 ℃~32 ℃升温段进行了污染沉积量的检测。结果表明: 在试验初期的高温恒温段, 污染源与敏感表面温差高于0 ℃, 15.75 h内单位面积污染沉积量为1.68×10-4g/cm2; 在低温保持段, 温差一直低于-22 ℃, 23.37 h内单位面积污染解吸附量为1.08×10-4g/cm2; 真空试验的总污染沉积量为2.7×10-5 g/cm2。得到的结果证实了该QCM用于污染量检测的有效性。文中还初步分析了真空试验下的污染沉积过程, 为光学表面污染的预估与防护提供了依据。

For the surface pollution of an optical communication terminal, a 10 MHz Aluminized Quartz Crystal Microbalance (QCM) is developed to detect the amount of deposited pollution in real time during a vacuum test. By introducing a reference crystal, the QCM eliminates the influence of environmental factors substantially, and reduces the requirements for temperature accuracy and its theoretical mass sensitivity is up to 10-9g/cm2. Through an absolute calibration experiment, the practical mass sensitivity of the QCM is 10-8g/cm2, shows a lower cost and good practicability and can be used both in satellites and on the ground. According to different operating temperatures of pollution sources, the test is divided into 32 ℃ constant temperature segment, 32 ℃ to -27 ℃ cooling segment, cryostat segment and -2 ℃ to 32 ℃ heating segment. The results show that in the high temperature segment at begin, the temperature difference between pollution source and sensitive surface is above 0 ℃,and the amount of pollution deposition per unit area is 1.68×10-4g/cm2 in 15.75 h. In the cryostat segment, the temperature difference is below -22 ℃, the amount of desorption per unit area is 1.08×10-4g/cm2 in 23.37 h. Moreover, the total amount of deposition is 2.7×10-5g/cm2 in the vacuum test. These results confirm the validity of the QCM for detecting the amount of pollution deposition, analyze the deposition process under vacuum test preliminarily and provide a gist for predicting and preventing the pollution of optical surfaces.