Continuous Laser Ranging Technology Research Based On The Correlation

With the rapid development and depth study of navigation andpositioning, telemetry and radar technology, accuracy as well as measuringthe distance of ranging technology, that is the one of the core technology ofthem, has higher requirement. In recent years, The remote precise distancemeasurement techniques received more and more attention from variousfields, even has been viewed as one of the national strength’s Indicators.The existing laser ranging technology has been gradually unable to meetthis growing demand. For example, although the common laser impulseranging technology based on TOF can reach tens of kilometers, itsaccuracy is restricted by the width of impulse and the bandwidth of receivecircuit. On the other hand, the laser ranging based on phase and coherenceis quite precise, but because of phase’s period and the wavelengthrestriction in the coherence, these two methods cannot be used in remotedetection. Also, pseudo-random code wireless ranging was limited by therate of chip, and cannot achieve high precise ranging.This dissertation focuses on the theoretical and experimental study ofthe continue laser ranging based on the second order correlation and thechaotic laser ranging. The detailed contents include:1. Propose a ranging scheme based on the second order correlationfeature of thermal lightIn recent years, large amount of theoretical and experimentalresearches based on correlated optics show that thermal state has goodsecond order correlation, with femtosecond level FWHM and singlepeak feature. In this dissertation, we propose a ranging scheme usingthe second order correlation feature of the thermal light. The scheme has advantages of high-precision, no measuring dead zone and goodanti-jamming. On this basis, a thermal light correlated distancemeasurement experimental platform has been implemented, and aproof of principle experiment has been done. Expected results havebeen observed. After that, we analyzed the experimental data andphenomena, which lays a good foundation for further implementationof outdoor long-distance thermal light correlated distancemeasurement.2. Complete the software algorithms of ranging scheme based on thesecond order correlation feature of thermal lightThe second order correlation curve of the thermal light is calculatedthrough coincidence counting algorithm, so we propose a coincidencealgorithm, called discrete coincidence algorithm. This algorithm ismuch better than the common coincidence algorithm in the efficiencyand storage, and is suitable to the high-precision environment.Following the theoretical formula of the second order correlation curveof thermal light, we use the curve fitting algorithm, and rangingaccuracy upgrade more than two orders of magnitude.3. Research on the chaotic laser ranging based on correlationBecause FWHM of the pseudo thermal source prepared by groundglass is800ns, it does not have advantage when talking about practicalranging system. Some theoretical and experimental researchesindicated that the FWHM of chaotic laser is less than1ns. In thisdissertation we propose the ranging scheme based on the chaotic laser,and verify the auto-correlation feature of chaotic laser in experiment,and340ps FWHM of chaotic laser is obtained.