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What is the diameter of a fiber laser beam?

Published in Fiber Lasers 2 mins read

The diameter of a fiber laser beam can vary, but commonly ranges from 130 to 560 μm. This range allows for power densities of 0.6 MW/mm² to 20 kW/mm².

Fiber laser beam diameter is a crucial parameter that influences its performance in various applications. The diameter, often referred to as the spot size, determines the concentration of the laser's power and therefore affects the precision and efficiency of processes like cutting, welding, marking, and engraving.

Here's a breakdown of the factors influencing fiber laser beam diameter and its implications:

  • Factors Affecting Beam Diameter: The beam diameter is not a fixed value and can be influenced by several factors, including:

    • Fiber Core Diameter: The diameter of the optical fiber core directly affects the initial beam size.
    • Focusing Optics: The lens system used to focus the laser beam determines the final spot size at the workpiece. Different lenses with varying focal lengths can be used to adjust the beam diameter.
    • Laser Wavelength: The wavelength of the laser light also plays a role, with shorter wavelengths generally allowing for smaller spot sizes.
    • Beam Quality (M²): A measure of how close the laser beam is to an ideal Gaussian beam. Lower M² values indicate better beam quality and the ability to focus to a smaller spot.

  • Implications of Different Beam Diameters:

    • Smaller Beam Diameters:
      • Higher Power Density: Useful for precise cutting, engraving, and micromachining.
      • Improved Resolution: Enables finer details and intricate patterns.
      • Reduced Heat-Affected Zone (HAZ): Minimizes thermal distortion in materials.
    • Larger Beam Diameters:
      • Lower Power Density: Suitable for applications like surface treatment, cladding, and some types of welding.
      • Faster Material Removal: Can be used for applications requiring high material removal rates.
      • Increased HAZ: May lead to greater thermal effects on the surrounding material.

In summary, the beam diameter of a fiber laser is a critical parameter that needs to be carefully chosen based on the specific application requirements. A range of 130 to 560 μm is typical, but the actual value can be adjusted using various optical components and by selecting fiber with different core sizes.

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