Technology(3)

Laser communication more intuitive understanding is the use of laser transmission of information communication. Its technical principle and the principle of radio communication is similar, that is, the first sound signal modulated onto the red laser beam, and then send the laser with the sound signal.

The laser itself has the characteristics of high brightness, strong directivity, good monochromaticity and strong coherence. In addition to the language information language, the laser can transmit characters, data, images and other information.

The advantages of laser communications: large communications capacity, in theory, laser communications can simultaneously send 10 million television programs and 100 million road phone. Confidentiality, the laser is not only extremely strong direction, and can be used invisible light, which is not easily intercepted by the enemy, the confidentiality is good. The structure is light and the equipment is economical. Since the divergence angle of the green laser pointer beam is small and the directivity is good, both the transmitting antenna and the receiving antenna required for laser communication can be very small. Generally, the diameter of an antenna is several tens of centimeters and the weight is only a few kilos, microwave antenna, the weight of a few tons, more than ten tons of dollars.

Communications distances are limited to line-of-sight (kilometers to tens of kilometers) and are subject to the effects of the weather and even disrupt communications in harsh climates. Atmospheric oxygen, nitrogen, carbon dioxide, water vapor and other atmospheric molecules on the optical signal absorption; atmospheric molecular density and suspended in the atmosphere of dust, smoke, ice, salt particles, microorganisms and tiny water droplets and other optical signals Scattering effect. Clouds, rain, fog, snow and other laser so severely attenuated. Atmospheric turbulence caused by air convection on the Earth's surface can have effects such as beam deflection, beam spread, beam flare (random variation of bright and dark spots within beam cross-section), and image jitter (random jump of beam convergence point).

Different laser wavelengths have different reduction in the atmosphere in the house. Theory and practice show that the laser attenuation of the wavelength is 0.4 ~ 0.7 m, and the wavelength is 0.9, 1.06, 2.3, 3.8, 10.6 m, respectively. The laser with 0.6 m wavelength has stronger fog penetration ability. Atmospheric most powerful laser communication can be used for communication of rivers, lakes, border areas, islands, mountains, canyons and other places. It can also be used in microwave communication or coaxial cable communication, temporary repair equipment when interrupted repair. Blue green laser with wavelength of 0.5 m can be used for underwater communication or submarine communication.

Aiming difficult. The laser beam has a very high directivity, which brings with it many difficulties in aiming at the transmitting and receiving points. In order to ensure the aiming between transmitting and receiving points, not only the high stability and precision of the equipment are put forward, but also the operation is complicated.

The main application of laser communications: short-range communication between the ground; short distance transmission of fax and television; due to the large burning laser pointer communication capacity, for missile range data transmission and multi-channel communication between the ground. Global and satellite communications through satellite total reflection, and underwater submarine communications.

Laser TV is not only have their own table, in the content and the current smart TV no difference. Because the use of laser TV is the TV system, and even many TV brands are also launched laser TV. Their LCD TV and laser TV use the system is similar to the same resources to provide. So use the 2000mw laser pointer TV without worrying about no content. With the gradual enrichment of network resources, laser TV online can see a lot of high-definition content, the latest TV series, movies and entertainment programs can use the laser TV to watch. Past the projector needs a separate device, connect the player or a variety of boxes can see a large, this way OUT out. Laser TV is to see to see, do not worry about no see.

First, not the same place is the light source, laser light source life is very long, easily tens of thousands of hours to laser TV life comparable to LCD TV. Can be said that a laser TV use a three or five years is not a problem, no longer worry about the problem of light, this life cycle has been enough, after all, not all families have to use a TV for 10 years 20 years. Second, the laser TV is a reflection of the ultra-short focus of the technology of the projector, this ultra-short focal length 3000mw laser pointer TV can be achieved within 0.5 meters distance of 100 inches of the screen. In other words, laser TV can be placed in the TV cabinet on the projection of 100 inches, in the past the projector hoisting in the middle of the living room situation gone.

But laser weapons have advantages and disadvantages. For example, in the rain or dust weather, its combat effectiveness will be greatly reduced. The development of laser weapons in the United States, mainly facing the choice of high-energy laser weapons twists and turns, a variety of key technologies have yet to be overcome, research and development costs overdraft progress delay, laser weapons to be miniaturization and other issues, the existence of these problems is also greatly limited The development of burning laser pointer weapons has become a major obstacle to the installation of laser weapons.

Laser TV is able to achieve 100-inch screen, but the screen brightness enough? Brightness is not enough, the screen size is large, but the display is difficult to guarantee. So the brightness is not high, is a laser TV challenge a foundation of LCD. Now the laser TV brightness is basically 3000 lumens. But the rapid development of high power laser pointer light technology is expected in the second half of the release of new products, many began to configure a 4000 or even 5000 lumens of brightness. This brightness and then with the anti-light curtain, even if the lights to watch, the effect is also very to force. Laser TV brightness breakthrough so that this product no longer appear during the day can not be used at night must be dark paint to show the situation. So the brightness of the breakthrough is always a main line of laser TV, it is gratifying that the current laser light source brightness breakthrough faster. It is clear that the development of laser TV is not subject to brightness and stagnation.

In fact, laser weapons are a directional energy weapon. According to different combat purposes, can be divided into tactical laser weapons and strategic laser weapons two categories. Which tactical laser weapons is the use of 5000mw laser pointer as energy, as conventional weapons, as the enemy directly to the enemy, tank aircraft, such as killing damage, combat distance of 20km or so. The strategic laser weapons is more like a "big kill device", can attack thousands of miles away from the intercontinental missiles, but also attack the reconnaissance satellites in space and communications satellites. It can be said that high-base high-energy laser weapons is an ideal weapon to seize the advantages of space, so the world's major military powers are spending money to research and development.

Compared with microwave radars, which have the same application in the car, the laser radar working in the optical band has a higher distance resolution, angular resolution and speed resolution than the microwave level of 2-3 orders of magnitude. Therefore, the lidar in the measurement process can bring distance, angle, reflection intensity, speed and other richer information, with these data can generate multi-dimensional target images, to help us or the system has a more detailed awareness of the target.

In addition, due to the short laser wavelength, can launch a very small divergence angle (μ rad order) of the blue laser pointer beam, multi-path effect is small, that is not formed directional emissions, and microwave or millimeter wave generated multipath effects, anti- To achieve low altitude, low altitude target detection. The laser active detection has a characteristic that does not depend on the external lighting conditions or the radiation of the target itself. It is only necessary to obtain the target information by detecting the echo signal of the laser beam emitted by itself, so that all-weather work can be realized. However, the laser radar is susceptible to atmospheric conditions and the dust of the working environment, to achieve the all-weather working environment in the present terms or the most difficult thing.

In fact, the premise of laser radar technology is 3000mw laser pointer ranging technology. We can usually see the distance measurement method, from the categories can be divided into: laser time-of-flight method and triangular method. In simple terms, they are suitable for long distance ranging and short distance ranging. The TOF method can be divided into: pulse modulation (pulse ranging technology), the use of the target to the optical signal diffuse to measure distance; phase modulation, the intensity of the laser continuous wave modulation, by the phase difference to measure the distance information The The choice of LIDAR for different methods depends largely on its type and practical application.

Lidder is also divided into many categories. Starting from the modulation, there are mainly direct detection of lidar and coherent detection of lidar. Commonly used, including autopilot, robot, mapping used, is basically a direct probe lidar. More special, such as wind, speed and the like radar, the general use of coherent modulation. If you start from the application, that classification is more, such as laser range finder, 5000mw laser pointer three-dimensional imaging radar, laser radar, laser detection radar and so on. Among them, the laser three-dimensional imaging radar contains our well-known laser mapping, as well as automatic driving in the single-line laser radar and multi-line laser radar.

In the current automatic driving, there are single-line laser radar and multi-line laser radar points. Due to the high sampling frequency required in the application, triangulation and pulse ranging are used in close and long distance measurements, respectively. Among them, the single-line laser radar mainly through a high frequency pulse burning laser pointer range finder, plus a one-dimensional rotation scan to achieve the measurement. And its angular resolution can be higher than the multi-line laser radar, so pedestrian detection, obstacle detection (small target detection) and the front of the obstacle detection and so on, than the multi-line laser radar has more advantages. Multi-line program is also mainly for multi-channel single-line collection, which is also subject to volume and optical path restrictions.

First of all, the laser radar is used in infrared laser, this laser itself in the infrared band radiation is much lower than the visible light. Furthermore, the application will use a very narrow filter, directly to the strong background light filter, and then use infrared light to detect. So that we can get a high-quality lane line image, through the image of the gray, you can easily detect the lane line. In general, with a 20000mw laser pointer radar to do lane line detection, performance will be better than the camera.