Design Of Digital Phase Shift Laser Range Finder

Laser rangefinder is a necessary instrument in engineering surveying and mapping,in order to improve product technology and market competitiveness,surveying and mapping instrument manufacturers put forward the development of high-precision,long-distance,low-cost requirements of rangefinder,for this paper designed a digital phase shift laser rangefinder.The rangefinder designed in this paper only emits a single high-frequency modulated frequency laser signal.At the receiving end,the echo laser is converted into photoelectric current by the photodetector APD.After digital orthogonal phase discrimination processing and multiple average measurement processing,the rangefinder can achieve high-precision remote target distance measurement.The main work is as follows:1.Establish goals without cooperation under the condition of sending and receiving of the coaxial ranging equation and the error model of the orthogonal phase,and analyzes the influence factors of measuring range,the influence factors of orthogonal phase error are analyzed,through calculation shows that the orthogonal signal amplitude and phase shift will affect routine measurement precision,and different phase difference measurement,the error factors impact on the measurement range.2.Designed the related hardware circuit of digital phase-shift laser rangefinder,including sinusoidal modulation laser transmitter circuit,photoelectric detection circuit,filter amplification circuit,mixing circuit,AD acquisition,power supply and other hardware circuits,completed the assembly and debugging of hardware circuit and other development work of rangefinder circuit.3.Borrowing the existing optical and mechanical structure of the total station rangefinder head,and using the digital phase-shift laser rangefinder circuit developed in this paper,the experimental device was built and the ranging experiment was carried out.The ranging results showed that when the average power of laser transmission was 1mw,the range of no cooperative target was greater than 500 m,and the ranging accuracy reached(3mm+2ppm*D).