0p0 Page 398
Page 398
Zhou Guangzhao: "Minister Tang said that when the purity is 99.998%, the loss rate of glass fiber will be reduced to 20dB per kilometer. I think that the loss rate of not reaching 20dB per kilometer should be due to the error in purity. Do you want workers to refine One furnace?"
Zhao Zhongyao: "Refining a furnace of ultra-high-purity quartz glass requires repeating the purification process dozens of times. I can't wait, so I use most of the furnace to try drawing wires. I'm going to make glass tubes."
……
The manufacture of optical fibers starts with a glass tube about the size of a ping-pong ball in diameter.
Two glass tubes, one is ultra-high purity quartz glass with high refractive index, which is the core material of the optical fiber.Another glass tube, made of low-index glass, is the cladding for the fiber.There is a difference in the refractive index of the inner and outer layers, so that when the laser is transmitted in the fiber core, it will form total reflection and transmit forward along a broken line.
Workers in the glass factory wash the glass tubes in a dilute solution of hydrofluoric acid to remove impurities such as oil stains that may exist on the glass surface.
After thorough cleaning, Zhao Zhongyao and Zhou Guangzhao fixed the two glass tubes on a test bench converted from a lathe, and the holes of the glass tubes gradually approached each other.The place where the two glass tubes meet is just the nozzle of the hydrogen-oxygen flame. After ignition, the place where the glass tubes meet is softened, and finally the two tubes become one.
Then the gas is injected, the film is reacted, heat processed, and the tube collapses from a hollow tube to a solid tube.
"It takes half a day for our small laboratory workshop to burn and pull out a roll of optical fiber. What should we do if we want to mass-produce it in the future?" Zhou Guangzhao asked.
Zhao Zhongyao: "Mass production is still far away. But the Ministry of Heavy Industry is already planning a special factory to manufacture this thing."
The glass tube was hoisted vertically and slowly inserted into a furnace with a temperature of 2000 degrees Celsius.
The glass tube softens and the glass liquid drips. The 0.5mm optical fiber was pulled out, and Zhao Zhongyao sighed: "Let's find a way to make 0.2 to 0.3mm optical fiber, 0.5mm is not easy to bend."
Wang Dayan: "If it is made thinner, the composition of the two types of glass is prone to faults."
The glass tube is drawn into glass filaments.The core of the glass tube is the core material, and the outer tube is the cladding material. The drawing process is not good, and a certain section of the glass filament may only contain one of the materials.If a certain section has only the cladding and no core material, the light transmission here will be broken (the loss rate will increase sharply).If, on the other hand, only the core material has no cladding, then this section will leak light, and the loss rate will increase sharply as a result.
Zhao Zhongyao: "We are now in the stage of semi-manual experimentation. The equipment can be fine-tuned, and the places that are easy to crack can be manually corrected. Light Zhao! Where are you going?"
Zhou Guangzhao carried a coil of optical fiber that was not easy to bend just pulled out on his shoulders, like a swimming ring: "Mr. .”
……
Zhao Zhongyao plans to start over and try to make 0.3mm optical fiber, which has to start with splicing glass tubes.
After working until the second day, a 0.3 mm filament was pulled out.It does feel a lot softer.
"The theoretical diameter is 0.3 millimeters, the smallest diameter measured is 0.282 millimeters, and the largest diameter is 0.330 millimeters... That's it."
Seeing Zhao Zhongyao pull out the first batch of 0.3mm glass filaments, Wang Dayan asked: "Verify?"
Zhao Zhongyao: "Da Yan, turn off the lights."
The laboratory has a large area. After turning off the lights, only two windows on one wall were left with light, and it suddenly became dark.
The 0.3 mm optical fiber pulled out now has been integrated into a 12-meter-long line, and 19 optical fibers are paralleled into one strand.
This is probably the first fiber optic cable in the world.
Optical cables are relatively soft, perhaps even softer than copper wires.Zhao Zhongyao first found one end of the optical cable and held it in his left hand, then pulled the cable with his right hand to find the other end of the optical cable.
Of course, both ends are empty, and no input and output decoding devices are connected.
"Watch me do magic tricks," Zhao Zhongyao picked up a laser pointer and illuminated one end of the optical cable, where there were 19 exposed optical fiber ends.
When the laser pointer shines on it, the other end of the optical cable leaks bright light.
Wang Dayan: ...
If it is a wire made of ordinary glass, the light loss exceeds 12% when it travels 95 meters inside, and there is no light leakage at the other end of the cable.Now in the room, the leaked light is not only visible to the naked eye, but also quite dazzling.
Wang Dayan: "So, the experiment was successful?"
Zhao Zhongyao: "Come here, hold this end for me, and use the laser pointer to shine on the optical fiber without stopping."
Wang Dayan took over the lighting work, and Zhao Zhongyao, who was free, picked up the other end of the optical cable, separated the optical fibers inside with small pliers, and carefully checked each leaked light.
"One fiber is not bright. The light emitted by the other two fibers is dim, indicating that the loss rate has increased sharply in some places. Dayan, please change the incident angle of the laser pointer a little to ensure that each fiber absorbs the laser light. . . . Finally, one of the 19-meter optical fibers is radiating normally. Well, 12 of the 2 [-]-meter optical fibers are defective."
……
"Are the lines aligned?"
"It's all aligned, and it's all screwed on."
Zhou Guangzhao and two students from the second laser group requisitioned the only two T52 computers in Changchun Optical Instrument Factory.
The two computers are divided into two rooms. Zhou Guangzhao used the detector he made to connect the optical cable coil, and pressed the switch, and the three small lights on the detector turned on and off in turn.
"These three cables are indeed fine." Zhou Guangzhao said, "Oh, I haven't checked the integrity rate of Mr. Zhao's new optical fiber yet."
In the optical fiber drawing laboratory, Zhao Zhongyao checked the 0.3mm optical fiber in his hand again with a detector, and the result was the same as what he had just measured.
"After all, it is a small-scale self-made thing in the laboratory. The reliability is not good, but I feel that the process can be improved." Zhao Zhongyao said, "How is your side? Do you want to change this line for testing? "
"No, we are all ready to test online."
……
Beijing.
Tang Hua knew that Zhao Zhongyao was currently taking the second set of lasers to try out optical fibers, and he might have pulled out the optical fibers for testing.
"Ms. Zhao: Since you are leading the team to Changchun, I will be busy with other things in Beijing first. If there are other additional needs, I will give timely feedback. If there is a breakthrough in technology, I will contact you immediately."
Tang Hua sent a telegram to Changchun, asking them to figure it out for a while.
Zhao Zhongyao's call back the next day was: "I forgot to bring thick clothes, please contact Tsinghua University and pack the winter clothes you need to Changchun."
……
Tang Hua now has to deal with a bunch of machines that are probably from the end of the 19th century.
"From January to July this year, we set up a small blast furnace of 1 cubic meters in Langfang according to the roughly given plan."
Lu Da, deputy director of the Iron and Steel Industry Bureau, came back from Langfang and brought reports, drawings and simple models of the small steel factory.
"First of all, all the equipment of this small blast furnace strictly complies with the requirements of domestic production. From blast furnaces, refractory bricks to reciprocating steam engines for power, they are all produced by existing domestic factories."
"The effective volume of the furnace type is 30 cubic meters, the diameter of the hearth bottom is 1.58 meters, the diameter of the furnace waist is 2.34 meters, and the diameter of the furnace throat is 1.48 meters. The diameter of the big bell is 0.78 meters, and the interval of the big bell is 0.35 meters. The overall height is 11.49 meters, and the diameter of the tuyere is 10 cm x4 One, single gas riser."
"The foundation of the blast furnace is sand and stone installed with moisture-proof iron plates, and six cast iron pillars. The shell and abdomen of the furnace body are made of 9 mm steel plates, and the hearth is made of 6 mm steel plates, which are riveted and welded. One iron hoop. The lower two layers of the furnace bottom are made of 30 mm thick sand and gravel, the upper two layers are made of 305 mm refractory bricks, the hearth and belly are all refractory bricks, and the upper part of the furnace waist is made of sand and gravel throat and iron bricks."
"Double types are used for the furnace roof, and two manual cranks are installed, which can be opened and closed manually."
"Power blower, tube-type hot blast stove, three coal-fired boilers and three reciprocating steam engines, the steam production is 4.5-5.5 tons per hour."
"Tapping iron and slag are all manual operations. The cooling equipment shares a pool of 150 cubic meters. The steam water pump absorbs water by the river, and sends it to the cooling water pipe around the blast furnace through an iron pipe with a diameter of 10 centimeters, and sends it back after cooling."