Did you know that the laser lightsaber in the anime is realized by a laser pointer?

 Particles at high energy levels are excited by some kind of photon from outside, and they will jump from high energy level (E2) to low energy level (E1). At this time, light with energy ΔE will be emitted, and the radiated light happens to have the same frequency and direction as the light that excites it. In a certain state, we can also excite a strong light through a weak light. This phenomenon is called "light amplification by stimulated radiation", or laser for short. Particles at high energy levels are excited by some kind of photon from outside, and they will jump from high energy level (E2) to low energy level (E1). At this time, light with energy ΔE will be emitted, and the radiated light happens to have the same frequency and direction as the light that excites it. In a certain state, we can also excite a strong light through a weak light. This phenomenon is called "light amplification by stimulated radiation", or laser for short.

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The development of laser weapons in China first began in March 1964, but greater progress was made after the reform and opening up. China launched the "High-Tech Research and Development Program (863 Program)" in March 1986, and laser technology is one of the subjects in the 863 Program. Recently, a research institute discovered that they have created the most powerful laser so far, which may be widely used in nuclear physics and high-tech weapons in the future. This laser has a peak power of 5.13 petawatts (a petawatt) and a duration of 30 femtoseconds (1 femtosecond is equal to one quadrillionth of a second).

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Early laser pointers used a HeNe gas laser with a wavelength of 633 nanometers (nm), which was usually used to generate a laser beam with an energy of no more than 1 milliwatt. The cheapest laser pointer uses a deep red laser diode with a wavelength close to 670/650nm. The more expensive ones use 635nm red-orange diodes, which are easier to recognize by the human eye. There are also laser pointers of other colors, the most common one is green light with a wavelength of 532nm. In recent years, 593.5nm yellow-orange laser pointers have also begun to appear. 2005A 473nm blue laser pointer appeared in September. At the beginning of 2010, there appeared a "blue" (in fact, purple light) laser pointer with a wavelength of 405nm. The apparent brightness of the light spot irradiated by the laser pointer not only depends on the power and surface reflectivity of the laser, but also depends on the laser pointer. The color vision of the human eye. For example, because the human eye is most sensitive to green light with a wavelength of 520-570nm in the visible spectrum, and has a decreased sensitivity to redder or bluer wavelengths, green light appears brighter than other colors at the same power. The power of the laser pointer is usually measured in milliwatts. In the United States, lasers are classified by the American National Standards Institute and the U.S. Food and Drug Administration (FDA). Visible light (wavelength 400-700nm) laser pointers with power less than 1 milliwatt are classified as Class 2 (Class 2 or II); those with power between 1-5 milliwatts are classified as Class 3 A (Class 3A or IIIa). The third class B (Class 3B/IIIb) laser (power 5-500 mW) and the fourth class (Class4/IV) laser (power greater than 500 mW) cannot be promoted and sold in the name of laser pointers by law.

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