Fig. 1. Schematic diagram of Risley-prism system

Fig. 2. Schematic diagrams of main assembly errors in Risley-prism system. (a) TPE; (b) TBA

Fig. 3. Flow chart of PSO algorithm. (a) Flow chart of standard PSO algorithm; (b) PSO algorithm is used to identify system error; (c) PSO algorithm is used to obtain setting values

Fig. 4. Influence of vertex angle on height angle difference and azimuth angle difference. (a) Height angle difference; (b) azimuth angle difference

Fig. 5. System error identification results. (a) Direction change values of TPE and TBA of each prism; (b) angle change values of TPE and TBA of each prism; (c) curve of fitness function; (d) effect of motion boundary on final fitness

Fig. 6. Changes of setting values. (a) Changes in prism apex angle αiset and refractive index value niset with iterations; (b) fitness varying with iterations

Fig. 7. Pointing result distribution maps. (a) Theoretical value pointing results; (b) setting value pointing results; (c) relationship among fitting circles; (d) devation of pointing results from center of image