2,5-dimensional Large-scale Nano-laser Interferometer Length Measuring Signal Processing Subsystem

Nanotechnology is a new technology developing from the 20th century in 80's. More and more attention is paid to the study of nanotechnology all over the world. Nanometrology as an important branch of nanotechnology must be developed to achieve high precision measurement on nano level needed urgently at present in industry such as mechanic, material and electronic, etc. The project "2.5 dimension large range Nanometer measurement and calibration system " in processed belong to national scientific key special project of the10th five-year plan just feed the need of traceability of Nanometer in our country. The signal processing sub system introduced in this paper processes the signal coming from interferometer real time is a key part of the project for displacement measurement.At first, this dissertation dicusses the current situation of nanotechnology and high accuracy laser displacement measurement technology, then analyses and introduces the optical system of high precision polarization laser interferometer with the ability of restriction of common disturb witch will be used in the our project.The dissertation places its emphases on interference signal processing. At the beginning we designed an electronic circuit connected to optical part of interferometer for signal processing. The hardware system is mainly made up of three parts:low noise preamplifier, signal conditioning amplifier, digital signal processing with high speed DSP. Interference signal is mainly processed by software and partly processed by hardware. In order to process signal fast and accurately, the dissertation analyses completely the interference signal and its error, and then draws a conculusion that the three errors is the main error of the interference signal (dc voltage error, unequal amplitude of two signals, quadrature phase error of two signals). For the sake of eliminating the three errors of interference signal, we analyse and investigate the method of error compensation, finally confirm off-line compensation and on-line dynamic compensation two schemes. Within the dynamic compensation scheme, we creatively propose a good P method to realize dynamic compensation of error by software. Further more, we designed measuring software of interferpmeter with nanometric level resolution.Last chapter of this paper gives an experiment system witch can test the precision of the circuit system we designed. By the experiment system we tested the circuit noise level and checked the correction of data processing method. The experiment result shows that the circuit system can realize the resolution about 0.04nm and the dynamic compensation performance and precision of P method is good than the traditional Heydemman method. The circuit system can feed the need of the interferometer and whole system.The research work of the dissertation will provide important technical aisstance for the accomplishment of the project "2.5 dimension large range Nanometer measurement and calibration system " and contribute to early realizing the construction of nanometer scale national standard.