I Just Want to Be a Quiet Top Student

Optics is an important branch of general objects, and holography is a booming branch of optics, which uses coherent light interference to obtain all information of objects.

The holographic photosensitive sheet is placed on the xy plane where z=0, and the photosensitive sheet receives the reference light and the spherical wave emitted from the object point at the same time, and is developed into a holographic sheet.

A proof is needed here, the ±1st-order diffracted light behind the hologram respectively forms a virtual image and a real image of the object point, and the positions of the two image points are calculated.

Shen Qi considered the complex amplitude of the spherical wave in the z=0 plane, under the paraxial condition, that is, the center of the sphere is far enough away from the xy plane.

An approximate relationship can be obtained here:

[(x-x0)^2+(y-y0)^2+z0^2]≈∣z0∣+(x-x0)^2+(y-y0)^2/2z0

When the original reference light is used to illuminate the above-mentioned holographic film, a round of mathematical processing is required to obtain the complex amplitude of the holographic film.

......=βA^2Bexp{ik/2d0[(x-x0)^2+(y-y0)^2]}+......

This took Shen Qi a certain amount of time.

The truth is about to surface, the first item on the right side of the equal sign is the so-called "halo light" that basically propagates along the direction of the illumination light, the second item represents a divergent spherical wave, and the third item is another order of diffracted light.

The key is the third item, which can be rewritten by using u=sinθ/λ and k=2π/λ, factor exp(-i4πux).

In the end, Shen Qi completed the proof, and obtained the coordinates of the convergence point, that is, the real image point, as (x0-2d0 sinθ, y0, d0)

Arrived 10 minutes late and finished the optical test in 45 minutes. Shen Qi checked it and handed it in.

Under the watchful eyes of a group of sophomore senior brothers and sisters from the Academy of Fine Arts, Shen Qi didn't stay too long, handed in the test paper and left quickly.

In fact, Shen Qi was not the first to hand in the paper, there was a boy who handed in the paper earlier than him, about a few minutes earlier.

Shen Qi walked out of the classroom and found the boy who was the first to hand in the paper was standing by the window in the corridor.

The boy is wearing glasses, tall, close to 1.9 meters, black clothes, black pants and black leather shoes, with his hands in his trouser pockets, standing upright, overlooking the blue sky.

"This look, this demeanor, you can see that he is a top student and a fellow student." Shen Qi made a preliminary judgment on the boy.

Suddenly, the boy turned his head and glanced at Shen Qi, and said, "I haven't seen you before."

Shen Qi: "My name is Shen Qi."

The boy nodded, as a greeting, and continued to observe the smoggy sky.

Shen Qi walked to the window, next to the boy in the zoo, and looked at the sky with the boy, the visibility was very low.

The two just stood like this, without saying a word, and 3 minutes passed.

Shen Qi finally couldn't help it anymore: "Senior Brother, what did you see?"

The boy said: "Jupiter and Saturn are normal, but the trajectory of Uranus is abnormal."

Are you looking at the stars in broad daylight? Shen Qi replied calmly: "Uranus does not move along a precise ellipse, which can be explained as a dark force attracts it."

Boy: "No matter what, Newton's laws are absolutely true within the scope of the solar system."

Shen Qi: "I agree with your point of view, so Neptune was discovered."

A conversation between two Yankee university students actually revisited a classic case in the history of astronomy.

It was discovered that Uranus does not move in an elliptical orbit, and the laws of gravity were in danger of being overturned.

A physicist named Le Verrier boldly predicted that there must be a dark and invisible planet, which is attracting Uranus.

Soon after, the planet was observed by the Berlin Observatory.

It is light blue and very beautiful. People on earth named this blue planet after Neptune, the Roman name of Poseidon.

This is how Neptune was discovered.

Shen Qi is not good at astrophysics, but his teacher in the high school Wujing team is very good at it. Mu Rong's undergraduate degree is astronomy, and he upgraded to astrophysics during his master's and doctoral studies.

"Everything is consistent with Newton's law, the ellipse plane is not on the 'sky plane'." The boy said again.

"For farther distances, the law of gravity is also correct." Shen Qi said.

"Yes, we can not only understand nebulae, but also start from the law of gravity, and even gain some inspiration for the origin of stars." The boy said.

"What's your name, brother?" Shen Qi couldn't continue. This person is really good at pretending to be a B. I can't beat him in the branch of astrophysics. My senior sister with a Ph.D. in physics is required to do it.

"Yang Dingtian, major in astronomy." The boy introduced himself briefly.

"Yangding Tianyang Hierarch?"

"Yang Liwei's Yang is the man who determines the sky."

"Brother Dingtian is a sophomore, right?"

"Sophomore."

"It's better to meet by chance, it's almost time for dinner, why don't we have a drink or two? I believe you are a man with a story, and I have wine." Shen Qi guessed that this style, this way of pretending to be B, Yang Dingtian must have a place on the ranking list of the Academy's most powerful kings.

Yang Dingtian: "No need, please go back."

Shen Qi was not annoyed: "That's fine, then I'll go back to the Mathematics Institute first, and come to ask for advice another day."

"Are you from several colleges?" Yang Dingtian's calm face finally showed a hint of surprise.

"Freshman in the Department of Mathematics." Shen Qi found out that his popularity in the Institute of Physics is not as high as imagined, at least this Senior Brother Yang doesn't know him.

"Did you take the optics exam across majors as a freshman?" Yang Dingtian asked.

"I have already obtained a bachelor's degree certificate from the Department of Mathematics, and I am studying for a second degree in physics." Shen Qi told the truth.

"It seems that you are also a man with a story." Yang Dingtian couldn't help looking at Shen Qi a few more times, "I invite you to drink today."

The two walked together and walked towards the small restaurant outside the school.

"My past was very ordinary. I liked mathematics as well as physics. I was recommended in the competition and came to Yanda." Shen Qi filled Yang Dingtian with a glass of snowflakes and ventured into the world, and then filled it up for himself.

"IMO? Or IPhO?" Yang Dingtian drank the wine in his glass in one gulp, he was a bold man.

"IMO, what about you?" Shen Qi asked.

"My past is also very ordinary, IPhO." Yang Dingtian poured another glass after drinking, and added: "I have participated in two IPhOs."

Twice selected to the six-man list of Wujing national team, this is very hanging. Shen Qi respected Yang Dingtian and finished his glass of wine in one gulp: "Why did you choose astronomy?"

"Truth exists in the universe, but the vast majority of human beings are lost in oil, salt, soy sauce and vinegar." Yang Dingtian looked out the window and looked up at the sky with deep and firm eyes.

"Brother's structure is really grand." Shen Qixin said why don't you go to the sky, and he added wine to himself: "Let's talk about something down-to-earth, physics at the undergraduate level, which course is the most difficult?"

"Fortunately, it's not too difficult." Yang Dingtian said, "What is difficult in physics is not the technique, but the Tao. The Tao follows nature, and everything is inseparable from its original principles."

"Brother Dingtian, just tell me, what is the average score of your physics major?" In the constant communication and discussion, human beings have made progress. Shen Qi discovered from Yang Dingtian that the B system of the Academy of Physics is different from that of the Academy of Mathematical Sciences.