The Design Of Laser Rangefinder Used For Levelling Of Ground

Roughness measurement tools are widely used in daily life. The existing tools are not only backward but also the accuracy could not reach the requirement, so to design a kind of which is used for leveling of laser rangefinder could be better to solve this problem.This thesis is designed to take the phase method for laser ranging. The main design is used for the flatness measurement. The accuracy requirement is1millimeter and the furthest is10meters. Source part of the laser wavelength is905nm, the thesis is using the latest DDS(Direct Digital Synthesizer) method to create a precise frequency signal, and the frequency signal is used for laser modulation and signal mixer. The receiver adopts the APD, and the photoelectric response is improving thousands of times than the previous general photodiodes. The principle of subsequent signal processing is beat frequency to measure phase, and the master frequency compared with local frequency of beat frequency signal is10KHz, at the same time, the signal frequency stability is very good. The design is slamming the door before relying on the DSP to fast Fourier transform to measure time, to adopt the high precision time measurement chip is TDC-GP2, and the time measurement precision is2.5×10-2mm,so it is fully meet the needs of this design.