Abstract: Based on geometric optics and Cauchy dispersion formula, this paper completely explores the reasons for the formation of the atmospheric optical phenomenon of rainbow neon, and explains the maximum viewing angle of rainbow and the minimum viewing angle of neon. At the same time, a device that can reproduce the rainbowni phenomenon is designed, and a scheme for indirectly measuring the light viewing angle of each color of the rainbowneon based on the parallel principle is given. In the experiment, the red light viewing angle of rainbow and neon is measured by changing the concentration of NaCl solution, and compared it with the theoretical value on the image, and found that the two were in good agreement, indicating that the intensity of the emitting light of the rainbow neon phenomenon is indeed concentrated at the maximum viewing angle. At the same time, it also shows that the Cauchy dispersion formula is suitable for calculating the refractive index of NaCl solution.

Key words:  , rainbow reproduction device, chromatic dispersion, rainbow, angle of view