title: Parallel multiplex laser feedback interferometry.
abstract: We present a parallel multiplex laser feedback interferometer based on spatial multiplexing which avoids the signal crosstalk in the former feedback interferometer. The interferometer outputs two close parallel laser beams, whose frequencies are shifted by two acousto-optic modulators by 2Ω simultaneously. A static reference mirror is inserted into one of the optical paths as the reference optical path. The other beam impinges on the target as the measurement optical path. Phase variations of the two feedback laser beams are simultaneously measured through heterodyne demodulation with two different detectors. Their subtraction accurately reflects the target displacement. Under typical room conditions, experimental results show a resolution of 1.6 nm and accuracy of 7.8 nm within the range of 100 μm.
authors.affiliation: State Key Laboratory of Precision Measurements, Department of Precision Instruments, Tsinghua University, Beijing 100084, China.
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Precision Measurements, Department of Precision Instruments, Tsinghua University, Beijing 100084, China.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Precision Measurements, Department of Precision Instruments, Tsinghua University, Beijing 100084, China.
authors.forename: Shulian
authors.initials: S
authors.lastname: Zhang