Basic Properties of Lasers

Before the invention of the laser, the artificial light source of high-pressure pulsed xenon lamp has the highest brightness, and the brightness of the sun is not comparable to the ruby laser laser brightness, can exceed the xenon lamp tens of billions of times. Because lasers are so bright, they are able to illuminate objects at great distances. The beam emitted by a ruby laser produces an illumination on the moon of about 0.02 lux (the unit of light intensity), with a bright red color and a laser spot visible to the naked eye. If the most powerful searchlight is used to illuminate the moon, the illuminance produced is only about one trillionth of a lux, which is undetectable to the human eye. The main reason for the extreme brightness of the laser is directional luminescence. A large number of photons are concentrated in a very small area of space, the energy density is naturally very high.

The ratio between the brightness of a laser and sunlight is in the millions, and it was created by humans.

The color of a laser

The color of a laser depends on the wavelength of the laser, which depends on the active substance that emits the laser light, the kind of material that produces laser light when stimulated. Stimulating ruby produces a deep rose-colored laser beam, which is used in medicine, for example, in the treatment of skin diseases and in surgery. Argon, recognized as one of the most valuable gases, produces a blue-green laser beam, which has many uses, such as laser printing, and is indispensable in microscopic eye surgery. Semiconductors produce lasers that emit infrared light and are therefore invisible to our eyes, but have just the right amount of energy to decipher laser records and can be used for fiber optic communications. However, there are lasers that adjust the wavelength of the output laser.

Laser Separation Technology

Laser separation technology mainly refers to laser cutting technology and laser punching technology. Laser separation technology is to focus the energy into a tiny space, can obtain 105 ~ 1015W/cm2 very high irradiation power density, the use of this high-density energy for non-contact, high-speed, high-precision processing methods. In such a high optical power density irradiation, almost any material can be realized laser cutting and punching. Laser cutting technology is a brand new cutting method that gets rid of traditional mechanical cutting, heat treatment cutting and the like, and is characterized by higher cutting precision, lower roughness, more flexible cutting methods and higher productivity. As one of the methods for processing holes in solid materials, laser drilling has become a processing technology with specific applications, mainly used in the aviation, aerospace and microelectronics industries. The color of light is determined by the wavelength (or frequency) of light. A certain wavelength corresponds to a certain color. The visible light emitted by the sun's wavelength distribution range of about 0.76 microns to 0.4 microns, corresponding to the color from red to violet **** 7 colors, so the sun can not talk about monochromatic. Light sources that emit a single color of light are called monochromatic light sources, which emit a single wavelength of light waves. For example, krypton, helium, neon, and hydrogen lamps are monochromatic light sources that emit only one color of light. Monochromatic light source light wavelengths, although a single, but there is still a certain range of distribution. Such as neon only emits red light, monochromaticity is very good, known as the crown of monochromaticity, the range of wavelength distribution is still 0.00001 nanometers, so neon emits red light, if carefully identified still contains dozens of red. This shows that the wavelength distribution of light radiation, the narrower the interval, the better the monochromaticity.

Laser output light, wavelength distribution range is very narrow, so the color is very pure. To output red light of HeNe laser, for example, its light wavelength distribution range can be narrowed to the μm level, is the red light emitted by the krypton lamp wavelength distribution range of two ten thousandths. This shows that the monochromaticity of the laser far exceeds that of any monochromatic light source. The energy of a photon is calculated using E=hv, where h is Planck's constant and v is the frequency. It follows that the higher the frequency, the higher the energy. Laser frequencies range from 3.846 x 10^(14) Hz to 7.895 x 10^(14) Hz.

The electromagnetic spectrum can be broadly classified into:

(1) Radio waves - with wavelengths ranging from a few kilometers up to about 0.3 meters, which are used in the general band of television and radio broadcasting;

(2) microwaves - wavelengths from 0.3 meters to 10^-3 meters, these waves are mostly used in radar or other communication systems;

(3) infrared - wavelengths from 10^-3 meters to 7.8 x 10^-7 meters;< /p>

(4) visible light - this is an extremely narrow band of light that people can sense. The wavelength ranges from 780-380 nm.Light is an electromagnetic wave emitted when the electrons within an atom or molecule change their state of motion. Since it is a very small portion of electromagnetic waves that we can perceive by direct sensing;

(5) Ultraviolet light - wavelengths from 3 × 10^-7 meters to 6 × 10^-10 meters. These waves are produced for similar reasons to light waves and are often emitted during electrical discharges. Because its energy is comparable in magnitude to the energy involved in a typical chemical reaction, ultraviolet light has the strongest chemical effect;

(6) R?ntgen rays (X-rays) - This part of the electromagnetic spectrum, with wavelengths ranging from 2 × 10^-9 meters to 6 × 10^-12 meters. Roentgen rays (X-rays) are emitted when electrons in the inner layers of an electric atom jump from one energy state to another or when electrons decelerate within the electric field of the nucleus;

(7) Gamma rays - are electromagnetic waves with wavelengths from 10^-10 to 10^-14 meters. This invisible electromagnetic wave is emitted from within the nucleus of an atom, and this radiation is often accompanied by the emission of radioactive substances or atomic nuclear reactions. gamma rays are very penetrating and very destructive to living things. From this point of view, the laser energy is not very large, but its energy density is very large (because it is a small range, generally only a point), a short time to gather a large amount of energy, used as a weapon is also understandable. 1, thermal effect

2, photochemical effect

3, pressure effect, electromagnetic field effect and biostimulation effect.

Pressure effects and electromagnetic field effects are mainly produced by lasers of more than medium power, photochemical effects are particularly important in low-power laser irradiation, thermal effects are present in all laser irradiation, and biostimulatory effects occur only in weak laser irradiation.