Development Of A Multi-channel Laser Focusing Distance Variable Transceiver System

Optical antenna is a laser transmitting or receiving system which is based on the traditional structure of the space telescope. It is generated by the combination of the laser technology, the space optics technology and the modern photoelectric detection technology. Now it has been applied widely in earth science and meteorology, physics and astronomy, biology, military and other fields.This paper has investigated and designed a multi-channel laser focusing transmitting and receiving system which is based on the laser antenna. The system could be synchronized and can change the distance of detection in a particular direction and obtain the image of atmospheric echo signals at different distances. After describe the theoretical basis of the reflective two mirror system and the theory of Gaussian beam propagation, this paper calculates the actual converging spot size of the transmission system and analyzes the wavefront aberration of the off-axis paraboloidal mirror systems affected by the oblique or the defocus incidence. The oblique incidence will introduce the certain astigmatism and a small amount of coma, and the defocus incidence will produce the certain coma and a small amount of spherical aberration and astigmatism.The reflective structure of the multi-channel laser focusing transmitting and receiving system is adopted and consists of a single-channel laser focusing emitting system, a dual-channel off-axis receiving telescope system. The three channel of the system depend on the same reference axis. We give the results of optical and mechanical design of the system and analyze the image quality of the transmitting and receiving systems on the base of the wavefront aberrations, the spot diagram and the MTF curve of some fields. Finally, tolerance analysis are done with the wavefront aberrations as the evaluation index.We propose an alignment method which makes the three channel of the system depend on the same reference axis according to the system structure. The optical axis of the single-channel laser focusing emitting system is made as the reference axis of the system. Finally, the actual test results are obtained. The wavefront aberrations RMS of the system are0.0621λ,0.0812λ and0.0803λ respectively. The actual test results of the system have met the design requirements which must be better than λ/12.