Laser Principles
- What is Light?
- 什么颜色？
- What are Visible Rays?
- Differences between ordinary light and laser beams
- The Origin of the Word Laser
- Laser Principles
- Types of Lasers
- 激光波长分析
- 激光振荡基本面
- Laser Oscillation Tube Elements
Laser light is drastically different from normal light. Learn about laser principles and the characteristics of different wavelengths.
What is Light?
Light is a type of electromagnetic wave, and these waves have standard wavelengths. Starting from the longest, these wavelengths can be divided into radio waves, infra-red rays, visible rays, ultra-violet rays, X-rays, and gamma rays.
什么颜色？
当光撞击物体时，被物体反射的波长被人眼（视网膜）占据。发生这种情况时，我们将反射的波长视为对象的颜色。
根据波折射率不同length, therefore light is split. As a result, we are able to recognize a wide variety of colors. For example, an apple reflects red wavelengths of light (600 to 700 nm) and absorbs all other wavelengths of light.
black objects absorb all light and thus appear black.
What are Visible Rays?
Some electromagnetic waves fall within the range of wavelengths that can be seen by humans. These are called visible rays.
在短波长侧，可见光射线尺寸为360至400 nm。在长波长侧，它们的尺寸从760 nm到830 nm。人眼无法看到比可见射线短或更长的波长。
Differences between ordinary light and laser beams
Here's how laser light and normal light differs:
- 1) Lasers emit light beams with high directivity, meaning the component light waves travel together in a straight line with almost no spreading apart. Ordinary light sources emit light waves that spread apart in all directions.
- 2）激光束中的光波都是相同的颜色，一种称为单色性的特性。普通的光，例如荧光灯灯泡的光，通常是几种颜色的混合物，因此结合并看起来为白色。
- 3) As the light waves in a laser beam travel, they oscillate with their peaks and troughs in perfect synchronization, a characteristic known as coherence. When two laser beams are superimposed on each other, the peaks and troughs of the light waves in each beam neatly reinforce each other to generate an interference pattern.
| Directivity （轻波以直线行驶） |
Monochromaticity | Coherence | |
|---|---|---|---|
| 普通的光 |
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| Laser beam |
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The Origin of the Word Laser
激光一词是一个首字母缩写词，代表“通过刺激辐射的刺激放大”。
Laser Principles
当原子和分子吸收外部能量时，它们从低能状态转移到高能状态。这种高能状态被描述为激发状态。
一种toms that enter an excited state are unstable and will immediately attempt to return to a low energy state. This is called transition.
When transition occurs, light equal to the energy difference between states is emitted. This phenomenon is called natural emission. The emitted light then collides with other atoms that are in a similar excited state, inducing transition in the same manner. Light that has been induced to emission is called stimulated emission.
Types of Lasers
Lasers can broadly be divided into 3 major types: Solid-state, Gas, and Liquid.
最佳激光器将根据所需的处理应用程序有所不同。
| Solid-state | nd：yag
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YAG (Yttrium Aluminum Garnet)
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|---|---|---|
| Nd:YVO4(1064 nm) | YVO4(Yttrium Vanadate)
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| YB：纤维（1090 nm） | Yb (Ytterbium)
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| LD: (650 to 905 nm) |
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| 气体 | co2(10.6μm) |
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| He-Ne (630 nm) (red) is common |
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| 准分子（193 nm） |
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| 一种rgon (488 to 514 nm) |
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| Liquid | 染料（330至1300 nm） |
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co2Laser
co2lasers are mainly used for machining and marking applications.
co2lasers emit invisible infrared beams, traditionally with a wavelength of 10.6 μm. N2gas serves to increase the energy level of CO2，他的气可以稳定CO2energy level.
YAG laser(Nd：YAG)
YAG lasers are used for general-purpose marking applications on plastic and metal targets and for machining applications.
YAG lasers emit invisible near-IR beams with a wavelength of 1064 nm.
什么是yag？
YAG是固体，具有Y（Yttrium），A（铝）和G（石榴石）的结晶结构。通过发光元件的掺杂，在这种情况下，在这种情况下（新近hody），YAG晶体将通过从激光二极管吸收光进入激发状态。
YVO4激光（nd：yvo4）
YVO4lasers are used for ultra-fine marking and machining applications.
YVO4lasers emit invisible near-IR beams with a wavelength of 1064 nm, like the YAG laser.
什么是YVO4？
YVO4是固体，具有Y（YTTrium），V（钒）和O的结晶结构4(oxide), or Y (yttrium) VO4(vanadate). Through doping of a light-emitting element, in this case Nd (neodymium), a YVO4晶体将通过吸收激光二极管的光进入激发状态。
激光波长分析
波长：10600 nm
co2lasers have a 10,600 nm wavelength, which is the longest found in most industrial systems. Compared to YAG, YVO4和纤维激光波长，CO2波长更长10倍。
顾名思义，合作2lasers are generated through the stimulation of CO2气体。
Typical characteristics of 10600 nm wavelength range lasers
- 金属吸收不佳
- Melting and burning occurs due to the long wavelength and heat transfer
- Can process transparent objects like glass and PET
- Generally can't produce contrast or discoloration
波长：1064 nm
IR (infrared) light contains the most versatile wavelengths for laser processing. As the name implies, IR light contains the wavelengths longer than visible red (i.e. longer than 780 nm).
1064 nm波长范围激光器的典型特性
- Capable of processing multiple materials (including resins and metals)
- 无法处理(如透明的对象glass) since the laser light passes straight through
- Easily creates contrast on resins
波长：532 nm
Second Harmonic Generation (SHG) lasers use a 532 nm wavelength. This laser light is visible to humans, appearing green, and is produced by transmitting a 1064 nm wavelength through a nonlinear crystal. As the light passes through the crystal, it's wavelength is reduced by half. A YVO4medium is normally used because the characteristics of the beam are well suited for intricate processing.
532 nm波长激光器的典型特性
- High absorption rates in materials that do not react well with typical IR wavelengths and those that reflect IR light (such as gold and copper)
- 由于梁斑的较小，因此可以使用复杂的处理
- 通常无法处理透明的对象
- High peak power and limited heat transfer make 532 nm lasers ideal for micro machining and intricate designs
波长：355 nm
第三个谐波生成（THG）激光器具有355 nm波长，落入紫外线（UV）的光范围。一个YVO4or YAG laser is used to produce a fundamental wavelength (1064 nm) that gets transferred through a nonlinear crystal to reduce the wavelength to 532nm. That light is transferred through a second nonlinear crystal to reduce the wavelength to 355 nm.
355 nm波长范围的典型特性
- 紫外线在大多数材料中具有极高的吸收率，并且不会施加过量的热量。
- 一个很小的光束斑点可以很好地处理
- 大多数非钥匙紫外线激光器都需要光学晶体替换，这会影响整体运行成本。
激光振荡基本面
Here's a breakdown of the laser emission process
1. Absorption
当原子和分子吸收光能时，原子中的电子从低能状态（基态）变为高能状态。随着能量的增加，电子从其正常轨道转移到外轨道。这种增加的能量状态称为激发。
- 原子状态
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原子处于基础状态 
原子处于激动状态
2. Natural Emission
Excited electrons rise in energy levels relative to the amount of energy absorbed. After a period of time, high-energy electrons will attempt to return to a low energy state by emitting energy. At this time, light is emitted.
这种现象称为自然发射。
3.刺激发射
When incoming light interacts with high-energy electrons, the electron drops to a lower energy state and emits light of the same energy, phase and movement direction as the incoming source. In other words, a single injected photon produces a phenomenon where it becomes two photons. This is called stimulated emission.
Light produced from stimulated emission possess uniform energy, phases and movement direction. Thus, producing a multitude of light with stimulated emission allowing for the creation of strong light with those three elements set uniformly.
激光光是通过使用刺激发射现象进行放大的注射光而产生的。结果，它具有（1）单色，（2）相干和（3）高方向性的特征。
4. Population Inversion State
为了使用自然发射振荡激光束，有必要创建一个环境，在该环境中，高能状态的电子数量却高于低能状态下的电子。这称为人口反转状态。
In other words, when the amount of naturally emitted light exceeds the absorbed light, it becomes possible to effectively create a laser beam.
人口反转状态的电子
- =许多高能电子
- =很少的高能电子
5.激光振荡
When a single electron naturally emits light in a population inversion state, that light causes another electron to naturally emit light. This results in a chain reaction that increases the amount of light produced and creates a strong beam. This is how laser oscillation works.
人口反转状态的电子
- 一种
- 自然排放
- b
- Stimulated emission
Laser Oscillation Tube Elements
Three elements of a laser oscillation tube
一种ll laser oscillation tubes are comprised of the following three elements:
- 激光培养基
- Excitation source
- 一种mplifier
- 激光培养基
- Excitation source
- 一种mplifier
