Study on a ground measuring system for the far-field performance of space laser communication terminal

Characterization of a space laser communication terminal's far-field performance is vital. In this paper, a new far-field performance measuring system with simple structure is proposed, which can measure the far-field distribution, the tracking and pointing accuracy, the point ahead angle accuracy and the co-alignment of the transmit and receive beams. Based on theoretical analyses of the measurements, we illustrate how to design the practical measuring device. For the problem of locating focal plane of the lens under non-visible light, we propose a high-precision locating method based on Airy spot image. Several typical experiments were performed, and the results show that the error on the far-field distribution is less than 5%, the tracking and pointing accuracy is better than 0.22 μrad, and the measurement bandwidth is 200 Hz. Finally, the error of the measuring system is analyzed and shown to be consistent with the measured data. The developed measuring system is demonstrated to be a simple but with high-precision system.