Design of differential optical system of in plane remote displacement measuremen

In this paper, an optical system for in-plane remote displacement measurement is brought forward. The remarkable characteristic of this optical system is to use a big aperture lens to focus the waists of two Gauss beams on a scatter which have been expanded and collimated, so good laser Doppler signals and high measurement accuracy are achieved. The experiments prove that the measurement system consisting of this optical system, a lock-in amplifier and a digital filter can be used to measure the