We present a precision laser ranger system for the measurement of large manufactured components and structures. The system was developed based on a beat-wave interferometry principle. The light source of this system is a frequency-stabilized laser with a frequency stability of 1×10~(-7) (in open air) or 10~(-8) (in the laboratory). The laser operates in two longitudinal modes, and the two modes are generated in common resonator; therefore the two beams are naturally coaxial. The precision ranger system does not need a long guide or any heavy machinery. In this system an adaptive filter and a wavelet-transform program are used to improve the measurement accuracy. The system described here has a measuring range of 0-20 m and a measuring uncertainty of 30 μm/10 m.
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