The research of high-frequency phase shift and phase discrimination in a nanometer positioning system

Toward the problems of high-frequency phase shift technology and high precision phase discrimination in a nanometer positioning system which based on a laser heterodyne interferometer and phase-locked technique, a high frequency phase-shifting method to provide two-way signals both at 20MHZ frequency but with one presenting phase jumps is presented, which adopt a pulse suppression method and frequency divider principle to realize phase-shifting technology. And we present a phase difference measurement method, between two sinusoidal signals at same frequency, to achieve high-precision phase-to-analog voltage converter within low-frequency to radio-frequency range. An integrated circuit AD8302, used for RF/IF signal amplitude ratio and phase difference detection, as the key of phase discrimination unit. Experimental results show that: the high frequency phase-shifting system has the characteristic of high precision and real time detection, the accuracy of phase discrimination is better than 0.1°. So we can conclude that these methods can effectively solve the difficult problems about the generation of small phase shift and high-precision phase-to-analog voltage converter in the nanometer positioning system.