Applications of High-Energy Laser Technology in Marking and Welding

 

What is High-Energy Laser?

Since Maiman invented the world’s first ruby laser in 1960, laser technology has advanced rapidly and found extensive applications in industry, scientific research, and defense. With the increase in laser power, its industrial applications have expanded accordingly.

 

A high-energy laser must meet the "three highs": high energy, high beam quality, and high efficiency. Additionally, it must not only deliver high output energy but also maintain significant power. While energy can accumulate over time, laser processing requires both sufficient energy density and power density. Typically, high-energy lasers are defined as those with an average output power exceeding 10 kW, a duration of several seconds, and energy outputs of tens of thousands of joules.

 

The types and characteristics of high-energy lasers, including those under development, are summarized in Table 1

Table 1 Types and Characteristics of High-Energy Lasers
Type	Wavelength	Advantages
Pulsed Nd:Glass Laser	1.06 μm	- Located in the near-infrared atmospheric window with high atmospheric transmission rate.
		- Short wavelength, small diffraction divergence angle.
		- Large energy storage device, low device efficiency.
		- High power achievable, but difficult to achieve high energy, high repetition pulse output, and long emission intervals.
CO₂ Laser	10.6 μm	- High beam quality with stable and good mode; large output power.
		- High energy conversion efficiency; simple structure and mature technology.
		- Requires large emission systems to achieve small diffraction limit angles due to long wavelength.
Solid-State Laser (Nd:YAG)	1.06 μm (adjustable)	- Located within the atmospheric window.
		- Compact structure, high rigidity, reliability, and long lifespan.
		- Challenges include thermal management and power supply requirements for high-energy systems.
Semiconductor Laser	Varies by medium	- High-power semiconductor lasers are mature, with commercial models reaching several kilowatts.
		- Uniform energy distribution; adjustable spot shape.
		- High electro-optical efficiency, compact size, lightweight, and portable.
		- Disadvantages: average beam quality and high divergence.
Free Electron Laser	Continuously tunable (X-ray to microwave bands)	- Output wavelength can be adjusted as needed.
		- Theoretically high energy conversion efficiency with potential for development.
		- Requires high-brightness electron beams and large power sources.

 

 

Applications of High-Energy Laser in Welding

Laser welding utilizes the high energy density of a laser beam as a heat source. The beam is focused onto a small area via an optical system, creating a highly concentrated heat zone that melts and bonds materials into strong welds.

 

Components of a Laser Welding System

Laser Source: Core components include CO₂ lasers, YAG lasers, LD-pumped solid-state lasers, and semiconductor lasers. These must offer high output power, wide power adjustment ranges, gradual power ramping, stability, and reliability.

Optical System: Controls beam quality through collimators, beam delivery systems, and focusing systems. It incorporates high-damage-threshold optics such as spherical, aspherical, and planar lenses/mirrors. 

Beam Expander: Expands the laser spot (e.g., 2.5x) to improve beam mode.

Focusing System: Directs the expanded beam to the workpiece via reflective mirrors and focusing lenses to achieve optimal energy density.

 

Laser Welding Mechanisms

Thermal Conduction Welding (Power Density: 10⁴–10⁵ W/cm²):

Laser energy is absorbed by the material, generating heat that melts the surface.

Shallow penetration and slower speed, suitable for surface bonding. 

Deep Penetration Welding (Power Density: 10⁶–10⁷ W/cm²): 

High-power lasers vaporize material, forming a keyhole. Multiple reflections within the keyhole increase absorption and penetration depth.

Rapid welding with high depth-to-width ratios.

 

Applications of High-Energy Laser in Marking

Laser marking employs high-energy-density beams to create precise marks on surfaces by inducing physical/chemical changes or ablating material.

Components of a Laser Marking System

Laser Source: Common types include UV, fiber, CO₂, and semiconductor lasers.

Beam Control System:

Galvanometer Scanning System: Uses servo motors and mirrors to steer the beam, controlled by digital signals for pattern generation.

Focusing System: Utilizes f-θ lenses to focus the beam into a fine spot, with focal lengths determining marking range and precision.

 

Laser Marking Mechanisms

Thermal Processing:

High-power beams heat the material, causing melting, burning, or evaporation. Similar to welding.

Cold Processing (UV Lasers):

High-energy UV photons break chemical bonds in materials (e.g., organics) without heat generation, avoiding thermal damage to surrounding areas.

Laser Optical Components

We provide a range of laser optics, including lenses, mirrors, windows, prisms, and polarizers, characterized by:

High laser-induced damage thresholds

High transmission/reflection rates

Wide incident angles

Precise phase retardation

These components are widely used in laser welding, cutting, marking, micro-processing, and research. For product details, please refer to our catalog.