Design Of Reflective Optical Antenna Based On Freeform Surface And Study On Transmission Efficiency

With the development of modern communication network,Free Space Optical Communication(FSO),as a kind of outdoor wireless communication technology,has a broad prospect in the field of communication and plays an increasingly important role in modern communication.Today,free space optical communications can achieve high data rates of up to 400 GBP per data link,providing a very attractive solution for high bandwidth data transmission in places where fiber optic cables cannot be installed quickly.In the free space optical communication system,the optical antenna largely determines the optical gain,effective transmission area,transmission rate and transmission efficiency of the communication system,and is a very important part of it.Reflective antennas are widely used in space optical communication systems because of their advantages such as compact structure,no chromatic aberration and strong anti-interference ability.The coaxial reflector antenna has serious energy loss in the center of the secondary mirror.With the development of optical profile detection technology,freeform surfaces are warmly welcomed and widely used in various fields.The application of freeform surface related technology in the design of optical antenna will greatly improve the performance of the antenna,and it is of great significance to apply freeform surface technology to the design of optical antenna.According to the vector theory of reflection,the law of conservation of energy and the principle of equal optical path,a method of freeform surface optical antenna is proposed to solve the problem of energy loss in the center of secondary mirror of coaxial reflection optical antenna.An antenna example of a beam with a specific intensity is given to verify the effectiveness and practicability of the proposed method.Finally,the transmission efficiency under various unideal conditions is studied.The main work contents are as follows:(1)This paper introduces the research background of free space optical communication,expounds the history and present situation of freeform surface research,summarizes the polynomial description method and parameterized description method of freeform surface,and analyzes the design principle and design method of freeform surface and the detection technology of freeform surface.(2)According to the vector theory of reflection,energy conservation law and the principle of equal optical path,the method of freeform surface optical antenna is proposed to solve the problem of energy loss in the center of secondary mirror of coaxial reflection antenna.Based on this method,a new structure of optical antenna,namely a freeform reflector optical antenna,is designed iteratively point by point.The simulation results show that the designed optical antenna reduces the energy loss of the center of the secondary mirror of the coaxial reflection antenna and improves the transmission efficiency of the antenna.Meanwhile,the freeform surface antenna designed in this paper can achieve the purpose of controlling the intensity distribution of the output beam.The freeform optical antenna was optimized by using ZEMAX software.(3)The transmission efficiency of freeform surface optical antenna is studied.The transmission efficiency of freeform surface optical antenna is discussed when the receiving antenna and transmitting antenna are off-axis offset,the primary mirror of freeform surface antenna is off-axis and off-axis offset,the secondary mirror of freeform surface antenna is off-axis and off-axis offset,and the light source is off-axis and off-axis offset.