The reflective mirrors used in CO2 laser engraving and cutting machines are vital components that play a critical role in guiding and focusing the laser beam. These mirrors are designed to reflect the CO2 laser’s wavelength, which is around 10.6 micrometers (µm). The choice of reflective mirrors is crucial for ensuring efficient laser processing and achieving precise cutting and engraving results. Let’s explore the details of CO2 laser reflective mirrors, how to choose them, and their material composition:

1.Types of Reflective Mirrors in a CO2 Laser Machine:

Output Coupler (OC): The output coupler, also known as the first mirror, is located at the output end of the laser tube. It allows a small percentage of the laser beam to exit the laser cavity and create the laser output. The OC mirror reflects most of the laser energy back into the cavity to maintain laser oscillation.
Rear Mirror (RM): The rear mirror, also known as the second mirror, is positioned at the opposite end of the laser cavity from the output coupler. Its primary function is to reflect the laser beam back into the cavity, completing the optical path and supporting continuous laser emission.
Focusing Mirror (FM): The focusing mirror, also called the third mirror, is responsible for converging the laser beam to a small, intense spot on the material’s surface. It plays a crucial role in determining the cutting and engraving precision.

2.Material Composition of CO2 Laser Reflective Mirrors:

Substrate Material: The substrate material provides the physical structure and support for the reflective coating. Commonly used substrate materials include:

a. Silicon (Si): Silicon mirrors offer good thermal stability and moderate reflectivity for lower-power CO2 lasers.
b. Molybdenum (Mo): Molybdenum mirrors provide excellent thermal stability and are widely used as substrates for CO2 laser mirrors.
c. Copper (Cu): Copper mirrors have high thermal conductivity, making them ideal for high-power CO2 lasers, where heat dissipation is critical.

Reflective Coating: The reflective coating is applied to the mirror’s surface to achieve high reflectivity at the CO2 laser wavelength. Common coatings include:

a. Gold (Au): Gold-coated mirrors provide high reflectivity at the CO2 laser wavelength and good durability.
b. Dielectric Metal Oxides: Multilayer dielectric coatings are commonly used to achieve high reflectivity with low absorption.

3.How to Choose CO2 Laser Reflective Mirrors:

Laser Power Rating: Ensure that the mirrors are rated to handle the specific laser power output of your CO2 laser tube. Higher-powered lasers require mirrors with better thermal conductivity and durability.

Quality and Durability: Invest in high-quality mirrors made from materials with excellent thermal stability and resistance to laser radiation. High-quality coatings are crucial for efficiency and longevity.

Focus and Cutting Precision: Choose mirrors with precise curvature and quality coatings to achieve accurate focusing and cutting/engraving precision.

Alignment Stability: The mirrors should maintain precise alignment to prevent beam divergence or distortion. Sturdy mounts and precise manufacturing are crucial for stability.

Budget: Consider your budget and find mirrors that offer the best balance between cost and functionality.

Reputable Suppliers: Purchase mirrors from reputable suppliers or the original equipment manufacturer (OEM) to ensure compatibility and performance.

In conclusion, CO2 laser reflective mirrors are essential components in laser engraving and cutting machines, guiding and focusing the laser beam. The choice of materials, coatings, and quality directly impacts the machine’s performance and cutting/engraving results. Consider your laser power requirements, focus precision, budget, and choose reputable suppliers to make an informed decision.