Fig. 1. Schematic diagram of the heliospheric imager tested in this paper. The angles indicated by the blue arrows are the angles between the edge of the camera's field of view or the center of the field of view and the sun's rays. The WACH1 full field of view is 20°, and the WACH2 full field of view is 40°

Fig. 2. (a) Composition and working principle of the front-end diaphragm stray light test system and (b) physical diagram of the test device

Fig. 3. Linearity test of photomultiplier

Fig. 4. Test results of front-end stop stray light suppression

Fig. 5. Variation of test signal strength with time

Fig. 6. Test results of stray light suppression capability of heliosphere camera lens WACH2

Fig. 7. Propagation paths of the main structure scattering and air particle scattering

Fig. 8. Comparison of test results before and after replacement of two surfaces

Fig. 9. Schematic diagram illustrating Mie scattering test through selecting two rotationally symetric regions

Fig. 10. Test results of Mie scattering