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Therminology from lasers

Lasers are complex technology, which can make their specifications and attributes confusing to navigate. To help you better understand key laser product details as you shop, this article will explain the most common terminology in straightforward terms with real-world examples.

Laser terminology covers the fundamental principles, components, light properties, and applications of lasers, including LASER (Light Amplification by Stimulated Emission of Radiation) itself, coherence and monochromaticity of the light, active medium, pumping, optical cavity, diodes, wavelength, power, pulse width, and terms related to applications like ablation, collimation, and beam diameter. 

Fundamental Principles & Components

  • LASER (Light Amplification by Stimulated Emission of Radiation):

    The acronym describing the process by which lasers produce their light. 

  • Pumping:

    The process of exciting the atoms or molecules in a lasing medium to a higher energy level to initiate the lasing process. 

  • Active Medium:

    The material (gas, solid, or liquid) that amplifies light through stimulated emission to produce the laser beam. 

  • Optical Cavity / Resonator:

    A system of mirrors that contains the active medium, reflecting light back and forth to stimulate further emissions and amplify the beam. 

  • Population Inversion:

    A state where more atoms in the active medium are in an excited state than in a lower energy state, necessary for lasing to occur. 

Properties of Laser Light

  • Coherence: A characteristic where the light waves are in phase with each other in both time and space. 
  • Monochromaticity: The emission of light at a single or very narrow band of wavelengths. 
  • Divergence / Collimation: The extent to which a laser beam spreads out. A well-collimated beam has low divergence and maintains its narrowness over long distances. 
  • Wavelength: The "color" of the laser light, determined by the active medium. 

Applications & Related Terms

  • Ablation: The removal of material from a surface by vaporization or melting using a laser. 
  • Laser Diode: A semiconductor device that produces a laser beam. 
  • Beam Diameter: The width of the laser beam. 
  • Laser Classification: A system for categorizing lasers based on their potential hazards. 
  • Nominal Hazard Zone (NHZ): An area where the maximum permissible exposure level (MPE) for laser radiation is exceeded. 
  • Assist Gas: Used in laser cutting and welding to clear away molten material. 

Measurement & Control Terms

  • Power: The amount of energy per unit time produced by the laser, measured in Watts (W). 
  • Pulse: A single, discrete burst of laser energy. 
  • Pulsewidth: The duration of a laser pulse. 
  • Power Density: The amount of laser output per unit area (e.g., W/cm²). 
  • Radiant Exposure: The radiant energy per unit area, expressed in joules per square centimeter (J/cm²), particularly relevant for pulsed lasers.