There are mainly two methods for realizing white light in existing LED lamps: one is to excite yellow phosphor by a blue LED chip; the other is to achieve a proportional mixing of three monochromatic LEDs of R, G, and B. However, no matter which method is used, when light of different wavelengths is incident on the same lens non-perpendicularly, the angle of refraction will be different, resulting in chromatic aberration due to dispersion. In terms of spatial distribution, the chromatic aberration of lamps can be divided into the internal chromatic aberration of the spot and the chromatic aberration at the edge of the spot. The internal chromatic aberration of the light spot is mainly due to the fluctuation of the mixing ratio of various wavelength components with the spatial position, which causes color inconsistency; the external chromatic aberration of the light spot is mainly affected by the dispersion of a similar prism, making the light with large wavelength appear in the outer ring, such as a street lamp lens the yellow circle phenomenon in.