bookbashuk Chapter 230: The Camera Is Out
Chapter 230: The Camera Is Out
Li Yang even "invented" a special photosensitive paint for this purpose.
He first got a batch of phosphors from the factory, the kind used to make televisions, which had good luminous brightness and afterglow time.
He then prepared a silver iodide solution and used gelatin as a sensitizer.
Mixing the two and adding an appropriate amount of nitrocellulose creates a photosensitive emulsion that is extremely sensitive to light.
Just apply it on the glass and expose it for a few seconds, and the image projected through the pinhole can be "captured" and frozen immediately!
"With this, shooting, transmission and storage are no longer a problem!"
Li Yang held up the piece of glass coated with photosensitive agent, his face full of excitement.
He couldn't wait to set up the pinhole and put the glass in.
Sure enough, the light passing through the small hole cast a clear reflection on the photographic plate!
The layout of the entire laboratory is still vivid in my mind!
"It's done! With photoelectric conversion, we have a video signal!" Li Yang shouted excitedly, almost jumping up!
But on second thought, he felt troubled again.
"But how big a pinhole and how strong a light source would be needed to capture the scene clearly?"
He thought to himself and decided to do an experiment first.
Li Yang carefully set up the pinhole box and looked out from the laboratory window.
Inside the box was the photosensitive glass that he had carefully prepared.
When Li Yang carefully installed the photosensitive glass into the box, the optical system of the camera was completed!
He could not wait to set up this crude device and looked out of the laboratory window into the factory.
Sure enough, the light passing through the pinhole projected a clear inverted image on the photosensitive glass!
Although it is only in black and white, the layout of the factory and the activities of the workers are still vivid in my mind!
Li Yang was immediately filled with excitement. He succeeded! With his wisdom and hands, he created a pinhole camera!
But Li Yang knew that this was far from enough. To make this camera truly useful, the problems of image transmission and electrical control needed to be solved.
To this end, Li Yang began to study the amplification and transmission technology of video signals.
He first used a 75-ohm coaxial cable to connect the camera's photosensitive glass to the monitor.
Then, a convex lens is installed in front of the pinhole to expand the light flux and a micro CCD photosensitive element is installed in the box to convert the optical signal into an electrical signal.
The CCD was carefully modified by Li Yang. Its sensitivity and integration far surpass similar products on the market.
Next is the amplification and transmission of the video signal. In order to reduce the attenuation and distortion of the signal as much as possible, Li Yang selected high-quality copper-clad aluminum coaxial cable and installed impedance-matching termination resistors at the beginning and end.
He also used radio parts discarded by the factory to design a low-noise amplifier circuit.
First, a high-gain field-effect transistor is used to amplify the weak video signal dozens of times, and then several transistors are connected in series for multi-stage amplification to increase the signal to a level that can drive the display.
In order to suppress the high-frequency noise mixed in during the amplification process, Li Yang also added an LC filtering circuit between each stage of amplification.
In this way, Li Yang cleverly combined the components together and finally integrated them on a thumb-sized circuit board.
With this video signal conditioning module, the images captured by the pinhole camera can be transmitted stably and clearly to a distance of more than ten meters!
In order to facilitate adjustment and control, Li Yang also equipped the camera with a micro gimbal.
He machined two mutually perpendicular rotating axes out of aluminum alloy and drove them with a stepper motor.
By controlling the number of pulses of the motor, the angle and direction of the camera can be precisely adjusted.
Li Yang also installed two limit switches on the gimbal to prevent excessive rotation from damaging the structure.
As for power supply, Li Yang chose a small nickel-cadmium battery.
It is small enough to be hidden in the base of the gimbal, yet it can work continuously for five hours!
During the debugging process, Li Yang also installed an automatic aperture on the camera.
Drawing on the principles of the camera, he used a set of variable resistors and servo motors to control the opening and closing of the lens.
When the ambient brightness changes, the resistor senses the change in current and drives the motor to adjust the aperture size to keep the amount of light entering constant.
In this way, the camera can capture stable and clear images regardless of day or night.
After several days and nights of continuous hard work, a pinhole camera integrating optics, mechanics and electronics was finally born in Li Yang's laboratory!
It is compact, precise, and fully functional, and is not inferior to similar products in the 21st century!
Li Yang looked at this work which was the crystallization of his hard work and wisdom with great satisfaction, and his eyes were filled with tears of excitement.
He never imagined that one day he would be able to build a camera on his own in this technologically backward era!
At this moment, he seemed to see his dream, shining brightly in the torrent of the times!
"With this weapon, it will be easy to monitor those guys with ulterior motives, right?"
Li Yang was very proud and had a sly smile on his face.
The front door, the living room, the kitchen, the toilet, and even the back window of the neighbor's house, as long as someone passes by, they will not escape his scrutiny!
While the neighbors were doing their sneaky things, he was watching from the dark, keeping everything in check;
When someone tried to harm him again, he had already seen through it and took precautions!
Of course, this is not the end. Li Yang knows that a single camera is not enough to monitor all the movements in the yard.
To achieve this, at least four or five cameras are needed to coordinate with each other and monitor the entire area.
More importantly, it is necessary to equip a centralized management system to aggregate and coordinate the scattered video signals, so as to truly exert the power of monitoring!
Thinking of this, a grand blueprint has emerged in Li Yang's mind:
A miniature camera is installed in each of the four corners of the courtyard, and the signal is connected to the control room in the center of the courtyard through concealed wiring.
In the control room, a large screen splitter is set up to splice the four-channel video images together for real-time display;
At the same time, it is equipped with a hard disk recorder, which can record 24 hours a day for playback and review;
Add to that pan/tilt control, voice broadcasting, and even infrared night vision systems, and it can be called a veritable "Skynet"!
When Li Yang thought of this grand idea, his blood boiled and he was eager to try it out!
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