Design And Implementation On Double Polarization Modulation Laser Ranging System

As a very important part in the field of basic physical measurement,length measurement has been concerned by professional researchers.Absolute distance measurement has important implications for the development of many science and technology.It can improve the manufacturing level of large scientific instrument,so that absolute distance measurement would exert important effect in scientific and technological progress.Simultaneously,as a basic physical measurement quantities,the process of measurement accuracy will improve the measurement accuracy of relative fields.Aiming at the phase accuracy and fuzzy distance in phase method of laser ranging technology,interferometric phase demodulation and continuous wave swept ranging method has been put forward in this article.We named it the second polarization modulation laser ranging system in this article.The light sauce was changed into polarized light by the PBS in front of the system,and the polarized light was demodulated when through the PBS for the second time.The phase information was carried by the phase difference between the polarization components in X axis and Y axis respectively.The phase demodulation is complied when the polarization components of X axis and Y axis interference in the PBS.This process is similar to the mixing technology in phase simulation technology,which transfer phase information to light intensity information.The ranging system change modulation frequency in uniform step,signal detection module measure intensity value when the modulation frequency changed.When the measurement distance is integer multiples of microwave wavelength,the smallest intensity signal is detected,and the distance result can be calculated by measuring two adjacent smallest intensity signal.In this method,the phase noise can be reduced,and the ranging accuracy can reach 10^-6.Based on this ranging system,the influence of modulation frequency on phase method of laser ranging technology in this article.The ranging accuracy has been improved ten times by selecting the appropriate modulation frequency.To overcome the influence of atmospheric environment changes in ranging system,we compensated the refractive index of air.In these all method,the system performance of polarization ranging system is improved,and has laid a good foundation of commercialization.