超大型光学镜面面形的纳米定位技术

电容式传感器在纳米级测试中得到了广泛的应用，但是对环境条件要求较高，检测中温、湿度的变化、传感器本身结构乃至其电路性能等因素，将直接影响测量的准确度和灵敏度。介绍了大型天体望远镜光学镜面面形的控制方法和工作原理。该大型天体望远镜Φ１０ｍ的主镜由３６块对角线长１．８ｍ的六角形子镜拼接而成，应用电容测微技术使此超大型镜面的共面性达到纳米量级的定位控制。通过检测原理的分析，阐述了电容式传感器在使用中提高其准确度和长期稳定性的理论分析和具体技术措施，并针对国内正在研制的ＬＡＭＯＳＴ超大型天体望远镜实际应用环境和技术指标要求，提出新的差动式传感器，并采用新材料和高集成度的进口新器件，以满足传感器在温、湿度变化大的条件下实时监测的要求。

Nanometer positioning technology of the surface form for very large optical mirror

The capacitive transducer has been widely used in the field of nanometrology. But the ambient condition should be very strict in the process of measurement because the temperature and humidity; even the construction of transducer itself and the performance of the circuit would directly affect the measuring accuracy. The theory and methods of controlling the surface form of the optical mirrors in large scale celestial telescope are introduced. The main mirror of the telescope, 10 m in diameter, consists of 36 pieces of sub mirrors. Each sub mirror is hexagon and 1.8 m in diameter. The positioning technique of the capacitive micro measurement that make the co surface of large mirror up to nanometer is put forward. By analysis of the measuring theory and several concerned methods, the accuracy and long term stability of the transducer have been improved. To adapt to the environment and technique specifications of the telescope, the transducer which use new material and new large scale integrated electronic device are employed. It can meet the need of real time measuring and monitoring in the condition of varied temperature and humidity.