Light is a kind of wave, so it is inevitable to observe the interference phenomenon of light. In 180 1 year, British physicist Thomas Young (1773- 1829) successfully observed the interference of light in the laboratory.
Only two coherent light sources with the same frequency, constant phase difference and consistent vibration direction can produce optical interference. The light emitted by two ordinary independent light sources cannot have the same frequency, let alone a fixed phase difference, so they cannot interfere.
The picture below shows the double-slit interference principle of students' experimental light.
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Thomas Young's double-slit interference experiment
1807, Thomas Young summarized and published Lectures on Natural Philosophy, comprehensively arranged his work in optics, and described the double-slit experiment for the first time: put a candle in front of a paper with a small hole, thus forming a point light source (light source from a point).
Now put another piece of paper behind the paper, the difference is that two parallel slits are opened on the second piece of paper. The light emitted by the small hole passes through two slits and is projected on the screen, which will form a series of alternating light and dark stripes, which are now called double-slit interference stripes.
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Thomas Young described the experiment of double-slit interference, and later history proved that this experiment can rank among the five most classic experiments in the history of physics. But he thinks that light is a longitudinal wave propagating in the etheric medium. This contradicts the polarization of light, but Yang did not give up the wave theory of light.
Yang's works ignited the fuse of revolution, and the theory of light fluctuation finally returned to the historical stage after a hundred years of silence.
However, it was not easy at that time. In the era when particle theory was still dominant, Yang's paper began to be ridiculed and satirized by the government and attacked as "absurd" and "illogical". In the past 20 years, no one has cared. In order to refute, Yang specially wrote a paper, but there was nowhere to publish it, so he had to print it into a booklet. But it is said that "only one copy was sold" after the release.
18 18, Fresnel supplemented Huygens' principle with the interference principle of light, put forward huygens-fresnel principle, perfected the diffraction theory of light, and won the prize.
As early as 18 17, facing the contradiction between wave theory and polarization of light, Yang realized that if light is a shear wave, the problem might be solved, and wrote to him, and then conveyed this idea to Fresnel.
So Fresnel, who had realized this by himself at that time, immediately explained the polarization with this assumption and proved the transverse wave characteristics of light, which made the wave theory of light enter a new period.