Otaku Engineer in Great Tang Dynasty Chapter 764: Holiday!

"Shanchang, in that case, I can say that I have succeeded~? Then what you promised me should count!"

Hearing Li Zexuan's affirmation, Mo Lingwei became excited and said quickly.

Li Zexuan chuckled and said, "Hehe, this is far from success! What I said at the beginning was that I asked you to build an astronomical telescope. Do you think you can see the moon in the sky with this little thing, Miss Mo? ~?"

Mo Lingwei blinked curiously and said: "Why can't it work? My clairvoyance can already see far away, can't I use it to see the moon~?"

"Of course not!"

Seeing Yan Shaoning next to him was also confused. Li Zexuan had to patiently explain to him: "I told you before that the magnification of this clairvoyance is related to the focal length of the objective lens and the eyepiece. The clairvoyance you are doing now, The magnification is at most about seven to eight times. That is to say, if you use this one to look at a distance of one hundred feet, you will be zoomed in to look at a distance of about ten to twelve feet, and the moon is about eight feet away from us. Eighteen thousand miles, you said that with this thing, we can see what the moon looks like?"

(Usually the moon is about 400,000 kilometers away from the earth. In the Tang Dynasty, Li Shimin's double steps (one step on each of the left and right feet) were used as the size standard, called "step", and 300 steps were defined as one mile , One-fifth of a "step"-one-chi, Tang Dynasty-Chihe is now 0303 meters, one li is 454 meters, the distance between the earth and the moon is almost equivalent to the Tang Dynasty's eighty-eight thousand li)

"Eight eighty-eight thousand miles? How far is that~?"

After the two listened, they were speechless. Yan Shaoning thought for a while and asked: "Xiao Xuan, according to your opinion, do we only need to increase the magnification of the clairvoyance~?"

Li Zexuan moaned his chin and replied: "Well, but it's not just a matter of increasing the magnification. When the magnification is too high, the final image of the clairvoyance will be distorted. You must find a way to reduce the problem of imaging distortion. , Otherwise it’s useless no matter how high the magnification is~!"

Mo Lingwei frowned, wondering: "Mountain Chang, what is imaging distortion?"

No blame for her ignorance, mainly because this knowledge has not been mentioned in the first volume of the physics textbook.

Li Zexuan organized some language and explained: "I have told you about the imaging principle of convex lenses. In fact, those are the cases where the light is close to the central optical axis, but in fact there is always a part of the light that is not close to the central optical axis. They are at the edge of the lens. Compared with the actual object, the final image formed by this part of the light is deformed to a certain extent. I call this distortion!

For clairvoyance, if you want to obtain a higher magnification, the length of its overall optical path will become longer. At this time, after a small distortion passes through such a long optical system, the degree of distortion will be Bigger! So when you increase the magnification of clairvoyance in the future, don't neglect the image quality! According to my experience, as long as you can guarantee a magnification of more than 30 times, you can basically meet the requirements of astronomical observation! "

Li Zexuan is very familiar with telescopes. When he was in high school, a buddy in his dormitory brought a telescope. The famous name is to see the scenery opposite the dormitory, but the opposite is only girls. dorm room. In the end, Skynet was restored, and it was not leaking. The boy's telescope was confiscated by the class teacher who suddenly checked the bed.

When he was in college, he benefited from the school’s geographical location. On an open day of a planetarium in the capital, he spent 35 yuan to go in and sneak around. It was considered that he had used the astronomical telescope himself. The majors studied during the undergraduate and graduate studies involved a considerable part of optical knowledge. He even polished the lens by himself during the internship. In the era of the Tang Dynasty, he can be called an expert in optics! This is also why he can explain to Mo Lingwei and Yan Shaoning so well.

"Then Xiaoxuan, how do we solve the imaging distortion~?"

To be honest, Yan Shaoning is not shocked at all about the endless source of novel knowledge that always pops out of Li Zexuan’s brain, because he has been numbed by shock. The more important thing than shock is that he needs to do his best. To absorb the new knowledge confided by Li Zexuan.

"This is difficult!"

Li Zexuan shook his head complicatedly. For the imaging distortion and chromatic aberration of the lens, the method of cementing the lens is often used in modern times. By fixing two or more lenses with photosensitive glue, and then baking with ultraviolet light After two curing processes, a set of cemented lenses can be obtained.

In some modern precision optical components, such as microscope objective lenses, telescope eyepieces, etc., all of which are used are lens groups cemented by photosensitive glue. If only a simple convex lens or concave lens is used, it is difficult to obtain better imaging results.

But in this era where basic science is extremely backward, it is no different from idiotic dreams to control imaging distortion like modern optical lens companies. Not to mention that there is no photosensitive glue, and even pure ultraviolet light cannot be obtained~ IndoMTL.com~In this case, how can a cemented lens group be made!

"Although it is difficult, you can think of a way to replace a simple single lens with a lens group composed of many small lenses closely spaced, and keep the overall imaging optical path unchanged! The result is obtained Maybe it will be different~!"

After thinking for a long time, Li Zexuan could only use a dead horse as a living horse doctor and said.

Yan Shaoning and Mo Lingwei are both lost in thought.

.............................

"Clang clang clang~!"

With a burst of "crispy" gongs and drums, today's training at Yanhuang Academy finally ended. Qin Qiong (who was late in the morning because of the heavy rain), as the Academy's military training chief instructor, decisively blew the horn of orders.

"School out~!"

The enthusiasm of the students for training today is very high, there is no need to deliberately embarrass people on this, so Qin Qiong's impression of the instructors is quite good. As soon as school is over, let the students go to school decisively, without any delay!

"Oh~! It's a holiday~!"

"I can finally go home to sleep in~!"

"Haha~! I will not come out for these two days! In the academy, it is really not easy to put a day or two off~!"

The students burst into cheers, and then Yanhuang Academy became a sea of ​​joy, and cheers could be heard everywhere. The students ran back to the dormitory like a gust of wind, then rushed out of the dormitory, out of the gate of the academy, and headed directly to Chang'an City below the mountain.

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