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What is a laser?　About its industrial | Matsusada Precision

What is a LASER?

The term LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Unlike natural light, which is typically a mixture of various colors (wavelengths), lasers emit coherent light at specific wavelengths. This artificial light source possesses unique properties not found in standard illumination.

Laser generation begins when an excitation source applies energy to a specific gas, liquid, or solid medium. This process excites the electrons within the medium's atoms to a higher energy level. As these atoms are unstable in an excited state, they release energy in the form of photons to return to their ground state.

This phenomenon triggers "stimulated emission." When a photon interacts with another excited atom, it causes that atom to emit a second photon identical in wavelength, phase, and direction. By amplifying this process within an optical resonator, highly coherent laser light is produced.

Key Features of Lasers

Lasers differ significantly from natural light or standard lighting sources. The fundamental characteristics that define laser light include:

  • Monochromaticity (Single Wavelength): Unlike white light, which contains a spectrum of colors, laser light consists of a single, specific wavelength (color).
  • High Directionality: The beam travels in a straight line with minimal divergence, allowing it to maintain energy over long distances.
  • High Energy Density: Because the beam does not spread significantly, energy is concentrated in a small area.
  • High Coherence: The light waves are in phase with one another, making lasers ideal for interferometry and precision measurement.

These properties make lasers indispensable for industrial applications where precision and power concentration are required. While ordinary light scatters and loses intensity, a laser beam maintains its focus and intensity, enabling applications ranging from long-distance sensing to material processing.

Difference between laser and common light | Matsusada Precision
Comparison between laser beam and incoherent light

Types of Lasers and Low-Power Applications

Lasers are generally categorized by their gain medium (oscillation source):

  • Solid-state lasers (e.g., YAG, Fiber lasers)
  • Gas lasers (e.g., CO2, Excimer, Helium-Neon)
  • Semiconductor lasers (Laser Diodes / LD)
  • Liquid lasers (e.g., Dye lasers)

Lasers are also classified by safety standards (Class 1 to Class 4) based on their output power and potential hazard to the eyes and skin.

Low-Power Applications (Class 1 & 2)

Lasers with relatively low output power, such as those in Class 1 and Class 2, are widely used for measurement, sensing, and consumer electronics. Semiconductor lasers (Laser Diodes) are particularly common due to their compact size and efficiency.

Common applications include:

  • Sensors and Measurement: LiDAR (Light Detection and Ranging), laser rangefinders, and barcode scanners.
  • Optical Storage: Reading and writing data for CDs, DVDs, and Blu-ray discs.
  • Positioning: Laser pointers and leveling devices used in construction.

In measurement applications like LiDAR, the system calculates distance by detecting the laser light reflected from an object. Because the beam is highly directional, it can detect distant targets accurately without physically altering or damaging them.

High-Power Industrial Applications

Class 3B and Class 4 lasers possess high output power and are primarily used for industrial material processing. Unlike low-power lasers used for signaling, these lasers generate significant thermal energy when absorbed by a target material.

Material Processing

High-power lasers can melt, vaporize, or chemically alter materials. Common processes include:

  • Laser Cutting & Drilling: The focused beam melts or vaporizes material (such as metal sheets) to create precise cuts or holes.
  • Laser Welding: The heat fuses materials together without needing filler metals.
  • Laser Marking: Altering the surface of a material to create permanent labels or codes.

One of the key advantages of laser processing is precision. The beam diameter and power can be finely controlled, allowing for the cutting of intricate patterns in materials ranging from metals to polymers.

Common High-Power Laser Types

Solid-state lasers (including Fiber lasers and YAG lasers) and gas lasers (such as CO2 lasers) are standard in heavy industry. High-power semiconductor laser stacks are also increasingly used for pumping solid-state lasers and for direct diode laser processing.

Safety Considerations

High-power lasers (Class 3B and 4) present significant safety risks, including eye injury and skin burns from direct or scattered beams. Strict safety protocols, including protective eyewear, interlocks, and beam enclosures, are mandatory when operating this equipment.

Reference (Japanese site)

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