| In recent years, laser space link technology has become a research hotspot athome and abroad. Because the free space laser communication system have gotmany advantages such as high optical gain, small beam divergence angle, highanti-interception ability, huge capacity of information and high rate and so on.In the stage of design and development of laser communication terminal, theperformance of space link simulation system must have detected. Thus theperformance parameters of the system or line would be determined including thecommunication distance and communication bit error rate, in order to optimize thedebugging to the system in the future. Besides, it’s difficult to promote effectiveexperiment on ground for the reason that the far distance among the communicationlaser communication terminals. Therefore, it is very indispensable to develop the testplatform for laser communication terminals and design the space link models systemto evaluation the performance of laser communication terminals in laboratory. Thespace link model system was designed through the analysis of the designcharacteristics of the laser communication terminal at home and abroad and thefunction of laboratory testing equipment for laser communication terminals. And acomplete analysis of the space link model system is introduced, such as its opticaldesign, its precision requirement, adjustment and test and experimental calibration and other aspects.Firstly, it is studied that the general situation of the development of lasercommunication system and laser communication terminal optical system testingplatform. Based on the working principle of laser communication system, testingrequirements for laser communication terminal optical system and design of indexfor laboratory testing platform is analyzed. The design principles of space link modelsystem is determined through the analysis of equation model of laser communicationlink and the principle of free space remote laser beam equivalent transmission.Then two kinds of space link model optical system is designed according to theoptical indices. One is transmitted type and the other is reflective type. Among themthe transmitted system has the continuous zoom structure which Conjugate distanceis invariant. The reflective system is designed by using the theory of optical systemimage magnification. Subsequently, the reflective system is chosen process intoprototype because of higher energy efficiency and on chromatic aberration. Afteranalyzing the motion precision of optical lens and aligning of optical elements, theanalysis results show that the system could achieve very high precision of energystability and meet the requirements of test system.Last of all, the experimental calibration of the system is completed after thealignment of the space link model system. The actual system focus is confirmed byactual magnification. And the relationship of magnification and movement ofmirrors has recalibrated. In addition, the experimental results show that Repetitivepositioning accuracy of magnification, Stability positioning accuracy, Energytransmittance, efficiency of the polarization and return loss of system all meet thedesign indexes and requirements of application. |
