Laser is a kind of light that does not exist in nature, and is emitted by excitation with the characteristics of good direction, high brightness, good monochromaticity and good coherence.
Laser is the 20th century after nuclear energy, computers, semiconductors, another major invention of mankind, known as the "fastest knife", "the most accurate ruler", "the brightest light! The most accurate ruler", "the brightest light". The light radiated by an excited atom is called "laser".
The highest light intensity achieved by focusing a laser has reached the order of 10^22 watts per square centimeter. In addition, this super-intense light field is extremely fast in the time domain, in the far-ultraviolet (XUV) band, the ultrafast time scale of the laser pulse has broken through the femtosecond (fs, 10^-15 seconds) to enter the as-second (as, 10^-18 seconds) new category.
Light is an electron in an atom absorbs energy, leaps from a low energy level to a high energy level, and then falls back from a high energy level to a low energy level, and when it falls back, the energy released is put out in the form of photons. The laser is the photon queue that is induced (excited), and the photons in this photon queue have the same optical properties and are extremely consistent in pace.
An analogy is that ordinary light sources, such as light bulbs emit different photons, and will run in all directions, very disunited, but the photons in the laser is the heart of one thought, the strength of one make, which leads to their invincibility, great power.
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Expanded Information:
Being called the brightest light because laser beams can be dispersed in one direction in parallel with little or no attenuation, they are so bright that at their brightest they are even 10 billion times brighter than the sun.
In addition, lasers excel in distance measurement, measuring distances so accurately that they are also known as the most accurate ruler.
Lasers have many properties: first, they are monochromatic, or single-frequency. There are lasers that can produce lasers of different frequencies at the same time, but these lasers are isolated from each other and used separately.
Second, lasers are coherent light. Coherent light is characterized by the fact that all of its waves are synchronized, and the entire beam of light appears as a "wave train". Again, laser light is highly concentrated, meaning that it has to travel a long distance before it disperses or converges.
Laser speed measurement is to carry out laser ranging on the object to be measured twice at specific time intervals, to obtain the object's moving distance in the period of time, so as to obtain the object's moving speed. Therefore, laser speed measurement has the following characteristics:
1, because the laser beam is basically a ray, the estimated speed distance relative to the radar speed measurement effective distance is far away, can be measured outside 1000M;
2, speed accuracy, error <1 kilometer;
3, in view of the principle of laser speed measurement, the laser beam must aim at the perpendicular to the plane of reflection with laser beams Point, and due to the measured vehicle is too far away, and in a mobile state, or the car body plane is not large, and lead to low success rate of laser speed detection, difficulty, especially on-duty police officers work intensity is very high, it is easy to fatigue;
4, in view of the principle of laser speed measurement, laser speed detector can not have the use of the movement, can only be applied in the static state; therefore, the laser speed detector can not be called "mobile electronic police". When used in a stationary state, the driver can easily find out that there is a detection, and therefore can not achieve the desired purpose;
Reference:
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