| The emergence of lasers has led to the rapid development of technology,and products such as beam scanning systems have been emerged one after another.Beam scanning systems are widely used for their performance in terms of cost,detection distance,and technology maturity.Risley prisms are widely used in beam scanning systems for their balance and operational stability.The principle of the extended Risley prism beam scanning system is analyzed,and several different structures are designed respectively.Multiple transceiver structures are applied,for example,directions of transceivers are controlled,optimal coordinates of the transceiver and the rotational speed of the prism and mirror in different extended structures are obtained.In addition,for the beam scanning systems with extended Risley prism,its application in indoor optical communication is discussed.In this thesis,the composition and structure of the beam scanning system are designed and optimized.For the scanning system,the related characteristics of Risley prisms are emphatically studied,for example,the scanning patterns of single-wedge prism and double-wedge prism.It is found that the scanning patterns obtained are different,when the rotation angular velocity and rotation direction are different.Besides,due to the influence of divergence angle,when beam exited from system and returned to system,it is rapid decrease in energy.Therefore,the beam expander optical system is optimized and designed,and a three-piece optical system is selected.Finally,modulation transfer function curve of the optical system is close to the diffraction limit,which indicates that the optical system has good performance.Then,the beam scanning system is applied to the rotating mirror lidar system.Due to the particularity of the Risley prism structure,the scanning performance of four different combinations are analyzed.And the effects of coverage range(360° in horizontal,280 in vertical),detection distance(110 m),and grid size(2°×0.2°)can be achieved,which is equal to mechanical lidar with 16 transceivers,since the point cloud distribution of four combinations in the horizontal direction are basically the same,variance is used to analyze the point cloud distribution.And it is obtained that when the three combined speed ratios are 33:28:21 and four sending and receiving coordinates,the point cloud has the best distribution uniformity in vertical.Besides,the Risley prisms are extended(using a single wedge prism).When the rotational angular velocity ratio of the prism and the mirror is 11:32 and four coordinates of the multi-transceiver structure,the system can realise the sane effects.Finally,the beam system system is applied to indoor optical communication.When factors are taken into consideration,such as cost,Risley prisms are rotated in the same direction at the same angular velocity.When there is only a single transceiver structure,due to the inherent defects of the prisms,there is a blind spot in the scanning center After the use of multiple transceiver structures and the resolution is 5 cm × 5 cm,the defects are overcome.when multiple systems work together,the resolution accuracy can reach 3 cm × 3 cm. |
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