为了实现光信号的离轴旋转连接，设计了一种新型的离轴旋转光纤传输系统。基于高斯光束传播理论，分析了大口径光纤准直器对高斯光束的扩束准直作用，利用ZEMAX 对准直器的结构和输出光束特性进行了优化。对离轴旋转光纤传输系统进行了实验测量，结果表明大口径光纤准直器输出光束在50 mm 的工作距离处能量分布满足高斯型，其束腰半径达到18 mm，远场发散角仅为5.48×10-2 mrad，在1.25 Gb/s 的信号传输速率及80 r/min 的转速下，系统的最大连接损耗为23.28 dB，整体性能满足了旋转部件之间稳定传输高速光信号的要求。

A new-type off-axis rotary optical fiber transmission system is designed to achieve the connection of the optical signals under the rotary state. The collimating and expanding effect of the fiber collimator with large aperture is analyzed based on the propagation theory of Gaussian beam, and the structure and output beam properties of the fiber collimator is optimized by ZEMAX. The relative optical characteristics of the transmission system are measured. The results show that the fiber collimator outputs Gaussian beam at a working distance of 50 mm. Beam waist radius and far- field divergence degree are 18 mm and 5.48 × 10- 2 mrad, respectively. The maximum connection loss of the transmission system is 23.28 dB when the signal transmission rate is 1.25 Gb/s and the rotation speed is 80 r/min. The overall performance of the transmission system satisfies the requirement of stability for high-speed optical signal transmission between the rotary parts.