Light cannot be weakened when it meets light.

When two beams of light with the same frequency are emitted in the same direction or relatively, if they are in the same phase, the amplitude of the light wave is enhanced and the intensity of the incident light to the human eye is increased; If the phase difference between them is 180 degrees, the light waves will cancel each other out and the human eye will not see the light. When the phase of two light waves changes from 0 degrees to 360 degrees, the intensity of light will increase->; Weaken->; Enhance change. We can also observe the enhancement and attenuation of light in the interference phenomenon of light.